March 2003 Gasification Archive

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From ronallarson at QWEST.NET Sat Mar 1 09:26:02 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:16 2004
Subject: Forwarding Ray W. on coppicing and Punchi Banda stove
Message-ID: <SAT.1.MAR.2003.072602.0700.RONALLARSON@QWEST.NET>

Stovers - Again I am forwarding with a few comments a valuable message from
Ray W.

-----Original Message-----
From: Ray Wijewardene [mailto:raywije@eureka.lk]
Sent: Saturday, March 01, 2003 3:38 AM
To: Ron Larson
Subject: RE: [STOVES] FW: [STOVES] Combustion, shape of sticks -

Sorry about that Ron.

Secateurs are tools rather better known to nursery-men, forresters and
orchardmen. The only 'snips' I know are the tin-smiths snips...like a pair
of heavy-duty scissors.... and if that is what you had in mind, they are
similar. Secateurs contain a spring to hold the jaws apart, and have curved
blades about 50 to 70 mm in length and are ideal for 'pruning' of the
branches of trees with a clean cut rather than with 'machetes' (Spanish) or
'catties' (south-Asian) which usually cause damage to the cut stock thus
affecting (retarding) regrowth of the base into further coppices. The
long-handles (about 70 cm long) enable a greater leverage for cutting
through the 30mm to 45 mm coppiced branches which are ideal for gasifiers
and therefater for further cutting the branches into 100 mm lengths which
flow well through the gasifiers. The use of saws takes MUCH longer to slice
through the branches we need to lop (coppice) and we now discourage their
use as they tend to encourage the next drastic step of the chain-saw.. and
the damage to the cause of sustainability which they bring about is
phenomenal.

(RWL): I sort of had that image - but had not realized the importance of
this tool - or its value over saw and machete.

The term C-4 is better known to botanists and agricultural scientists and
broadly relate to the rate at which photosynthesis converts atmospheric CO2
into carbon or biomass.... vaguely analogous to N2 fixation. While maize
(corn?) and sugar-cane and bamboo are categorised as C-4, most trees and
crops (rice, wheat etc) are C-3 and have a lower biomass and yield
production rate. It was our mutual friend
botanist/agro-scientist-par-excellence A.D. at Pune who first put us onto
the much greater potential of the bamboos for annual production rates of
biomass, and of the particular varieties at which they were looking such as
Dendrocalmus strictus for higher charcoal production... in the order of
several times that of the better-know NF trees such as Leucaena, Casuarina,
Cassia, and gliricidia with which we were acquainted. This was one of the
tremendous spin-offs of the 'stoves' conference in Pune which his family
most graciously organised. You will recall him demonstrating these in the
field.

(RWL): new list members will not know that we have talked about bamboo
quite a bit on this list. I hope Ray and A.D. can report on the use of best
varieties of bamboo for stove use. Are species with or without the central
hole preferred? I believe that artists using charcoal prefer that from
bamboo. Are the internet list on bamboo now carrying information on its use
for cook stoves or charcoal making?

There is already a healthy fuel-wood (rather than fire-wood) market building
up in Sri Lanka to feed the several gasifier-based industries which are
gradually taking over from furnaces and boilers using imported furnace/fuel
oil. The saving (reduction) in costs is in the order of 2/3 the cost of the
oil.. i.e. now down to 1/3 the heating costs. The farmers are paid $0.15 per
kg for the 30-45 mm branches (below 20% moisture level which they soon reach
at that size whereas logs - not accepted - are usually wetter). As an
incentive to pre-chop the branches tothe more desirable 100 mm lengths,
there is a price incentive to $0.2 per kg. We are thus endeavouring to
develop this as a fully sustainable small-farmer industry and thus
discourage the firewood market which comprises the non-sustainable practise
of cutting down trees (avec-the beastly chain-saws) and then chopping them
to smaller sizes.

(RWL): Has your cost come down or the cost of fuel oil gone up or both?
Congratulations on the rapid growth of your plantations. I am surprised
that you more than double the costs for the shorter lengths. Could you
confirm that the cost difference is $.20/kg.
Could you clarify on your making a distinction between fuel-wood and
fire-wood? it would seem that you would have dual use for the same product.

The current efforts of Punchi-banda are towards eliminating the auxiliary
fan in his wood-gas stove...and using only natural ventillation. Most
interesting results are evident. Initially, the flame is TOO strong
resulting also in unburnt gasses... but about half-way through the cooking
process it all levels out and thereafter only wood-gas burns with a blue
flame. Very surprisingly the same quantity of wood now lasts longer and
cooking times are thus extended; AND initial time to reach boiling is
reduced. This is MOST surprising indeed. He is now working on better control
of the burning initially (juggling the primary amd secondary air flows) and
also better control of the heat of cooking (i.e. being able to achieve
'simmering' when required).

(RWL): I hope you can encourage Punchi-Banda to write us with these new
results. For others, the P-B stove (seen at the Pune stove conference) has
been rather like that of Tom Reed's (with a small fan, now apparently going
out). When last heard, it was selling well in Sri Lanka. I have been
urging P-B to produce charcoal in this stove - and cannot tell if that is
happening.

RAY.

Ray - this is great news - please keep us informed.

Does anyone else know of any plantation work where biomass is competing so
successfully with fossil fuels? There is much to learn from what Ray has
been promoting in Sri Lanka. (And it sounds like much progress still to
hear about.

Ron

From kchisholm at CA.INTER.NET Sat Mar 1 11:05:12 2003
From: kchisholm at CA.INTER.NET (Kevin Chisholm)
Date: Tue Aug 10 18:30:16 2004
Subject: Is it Good to be Holey?? Re: [STOVES] Charcoal Briquetting
Machinery
Message-ID: <SAT.1.MAR.2003.120512.0400.KCHISHOLM@CA.INTER.NET>

Dear Richard

Thanks very much inded for your very helpful comments on holey briquettes. I
am sure that we will all learn a great deal from your insights.

From: "Richard Stanley" <rstanley@legacyfound.org>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Friday, February 28, 2003 5:49 PM
Subject: Re: [STOVES] Is it Good to be Holey?? Re: [STOVES] Charcoal
Briquetting Machinery

> The hole has certain very specific advantages or no advantages at all:
> The hole in the vertically aligned burning briquette provides
> 1) a draft

I would suggest that the "draft increment" is small, because the
"temperature increment" across the hole is small, in the case of "mass
burning" of briquettes. However, as you use them.... just a few at a time,
no combustion chamber, stood vertical, I can then see where you could indeed
get a decided benefit from a stack effect.

> 2) an insulated combustion chamber similar to Dean & Larry's rocket
> principles
> which means far faster ignition and less smoke "getting to temperature"

I am starting to think that the major benefit that you experience with your
holey briquettes is due to the fact that you are providing the "cooking
situation" with what is, in effect, a "combustible combustion chamber."

> 3) a far more rapid drying product (this applies obviously only to the wet
low
> pressure ambient temp process.

I would expect that you would inherently be able to get as much as 4 times
the drying rate with the hole. Drying rates are generally proportional to
the square of the principle dimension.

>
> Mass per mass, holey briquettes will far out perform wood or charcoal in a
rural
> or urban poor family cooking environment, where the local family stove is
un
> insulated or simply three stones, using only two or three briquettes at a
> time. Put them in an improved stove of most any kind and their
performance,
> while still improved, is no where near as improved as that of wood.

OK!! This seems to all hang together. You get your major benefit in
conditions of a small open fire, and much lesser benefit with larger
enclosed fires. More specifically:

1: They are used in inherently small fires
2: There are generally no features which would constitute a "combustion
chamber" in the case of an open fire, and the holey briquettes provides one.
3: The "competing fuels" are generally inferior in terms of
3:1 Moisture content
3:2 Fuel density
3:3 Fuel uniformity

The
~6%
> loss in volume/mass due to the 2.5 cm dia center hole of our standard 10
cm dia
> x 7.5 cm tall briquette is more or less insignificant when compared to the
> advantages mentioned above. You can't do much more with the holey
briquette as
> it stands . You can do a lot more to improve the burning efficiency of
wood.

I don't see any disadvantage to "loss of mass" because of the hole.
>
> We are observing use of 2 to 2.5, of the 125 gram holey briquettes is
> sufficient to replace 1.2 kg of fuel wood in the above domestic basic
cooking
> situation. This is based on a field observations in the same areas by the
same
> populations at the same times in east and central Africa over the past 9
years.

Wow!! 250 to 300 gms replacing 1200 gms wood!! About 1/4 the biomass
requirement.

> In the upper Andees where the fuelwood consumption figures are 3 to 4 kg
per
> person per day the briquette consumption increases proportionately to
between 4
> and 6 a day, same population same time of year as obsedrved over the past
two
> years.

There are different units involved here, but I assume the "3/4 fuel saving"
ratio still holds.

The open burning wood is commonly quoted to be between 6 and 10 %
> efficient. Two briquettes weighing in at a total of 250 grams with 75% the
> calorific value of wood obviously have to be preforming at far greater
> efficiency. As deducted by simple comparison of the given values, (viz 1.2
kg
> wood @ 8% = 250 grams of holey briquette @ X efficiency), the holey
briquette
> in the open burn situation would seem to be about 38% efficient.

I think you are being overly generous to stickwood by allowing only 8%
moisture, and harsh on yourself by not accounting for the moisture in your
fuel. Your results are probably better than this.

We have
not
> yet done absolute tests of heat values but have published comparative
tests
> between wood charcoal and the holey briquettes in hte american chemical
> societies' Journal of chemical innovation. (Feb 2001). The link is
> http://pubs.acs.org/subscribe/journals/ci/31/i02/toc/toc_i02.html
> which gets you to our cover article titled "A Unique Approach to
Conservation"
>
Very good!!

> The other advantage to the hole is seen in accelerating the drying the
> briquette. The above briquette comes out of the mold of the basic hand
press at
> about 500 grams. It dries unassisted, under ambient conditions in the
tropics
> and temperate latitudes (ex winter season) in 4 to 5 days, down to 120 to
140
> grams. A solid briquette of same blend same porosity and permeability
without
> the hole will take about 75 to 100 percent longer to dry . This amounts to
a
> lot of space for the micro entrepreneur, working as they often do, out of
their
> doorstep. While the center hole only increases surface area by about 10%,
it
> has the effect of creating a slight draft and an exposure just where the
> briquette moisture is most entrapped, in the center of the cylinder.

Your results are very much in line with what one would expect from first
principles.

Sure
other
> than one center hole can be used star shapes or the chinese multiport
holes as
> well but for us the basic engineering "KISS" principle (keep it simple
stupid)
> applies best.

A central "star shaped" hole would not help much from a drying standpoint.
The extra surface area may be helpful with the initial fire start, but it
would likely burn away very quickly.
>
> As to heat and pressure processes, this is One most widely recognised form
of
> briquette making and surely as noted the lower pressure and lower
temperature
> would have a negative effect on the integrity of the briquette as both
contibute
> to its binding strength. In the wet process however we are relying upon
the
> random alignment of natural fibers to do that job in a water slurry. We
use 150
> to 225 psi ambient temperature higher press ure and we generate heat which
> would tend to destropy the fibers. We start with a water slurry and wind
up
> with a product which is between .25 and .4 grams per cc. Density is
important
> but more important is the hardness and strength of the briquette.

Have you explored the possibility of making a "porous press?" That would
allow you to actually "dewater" as you made the briquette, and would lead to
a much greater briquette density. With a "tight press, I would guess that
you could go to 500 or 1000 PSI press pressure, with no significant increase
in briquette density. However, with a "porous press", you could almost
certainly get higher densities with LOWER press pressures.

The
whole
> trick with these briquettes is in knowing when to the biomass has
decomposed
> sufficiently without creating a briquete which will be too spongy or too
muddy

If you develop a "porous press", you should be able to markedly reduce the
incidence and extent of sponginess.

> . Its a different process entirely than the high pressure high temperature
> approach. Still one does not want a loose or even too tight a cake as
either
> gives nothing much more than smoke.

OK... is there an "upper limit" to desired density?
>
> For many stovers who want to test , or have tested holey briquettes in
their
> various improved stoves, I hope this clarifies a few issues raised.

Thanks very much for the insights into the issues which your holey
briquettes address!!

Kindest regards,

Kevin
>
> wholey yours,
> Richard Stanley

Don't press me. I'm dense enough as it is. BTW, would a poorly made
briquette make Holey Smoke? :-)

From hseaver at CYBERSHAMANIX.COM Sat Mar 1 11:53:45 2003
From: hseaver at CYBERSHAMANIX.COM (Harmon Seaver)
Date: Tue Aug 10 18:30:16 2004
Subject: Forwarding Ray W. on coppicing and Punchi Banda stove
In-Reply-To: <NGBBKDEHILILFNJPHEFIOEFFCJAA.ronallarson@qwest.net>
Message-ID: <SAT.1.MAR.2003.105345.0600.HSEAVER@CYBERSHAMANIX.COM>

On Sat, Mar 01, 2003 at 07:26:02AM -0700, Ron Larson wrote:
> Stovers - Again I am forwarding with a few comments a valuable message from
> Ray W.
>
>
> -----Original Message-----
> From: Ray Wijewardene [mailto:raywije@eureka.lk]
> Sent: Saturday, March 01, 2003 3:38 AM
> To: Ron Larson
> Subject: RE: [STOVES] FW: [STOVES] Combustion, shape of sticks -
>
>
> Sorry about that Ron.
>
> Secateurs are tools rather better known to nursery-men, forresters and
> orchardmen. The only 'snips' I know are the tin-smiths snips...like a pair
> of heavy-duty scissors.... and if that is what you had in mind, they are
> similar. Secateurs contain a spring to hold the jaws apart, and have curved
> blades about 50 to 70 mm in length and are ideal for 'pruning' of the
> branches of trees with a clean cut rather than with 'machetes' (Spanish) or
> 'catties' (south-Asian) which usually cause damage to the cut stock thus
> affecting (retarding) regrowth of the base into further coppices. The
> long-handles (about 70 cm long) enable a greater leverage for cutting
> through the 30mm to 45 mm coppiced branches which are ideal for gasifiers
> and therefater for further cutting the branches into 100 mm lengths which
> flow well through the gasifiers. The use of saws takes MUCH longer to slice
> through the branches we need to lop (coppice) and we now discourage their
> use as they tend to encourage the next drastic step of the chain-saw.. and
> the damage to the cause of sustainability which they bring about is
> phenomenal.

These sound exactly like what is known hereabouts as "lobbers". Sold in
probably just about every garden center, hardware store, etc. They cut cleanly
if sharp, but I'd think if you had much to harvest you'd be better off with a
power brush saw, which has a circular sawblade, sort of the industrial version
of a weedwacker. If you mean by "the damage to the cause of sustainability" the
fact that they use fossil fuels, well that can quite easily be obviated by
fueling them with ethanol. But a chain saw probably would be less desirable than
a brush saw, for one because the chain tends to leave more ragged cuts in some
species, and also because you have to bend over so much if you are cutting low.
At least that's been my experience in clearing brush in prairie restoration
projects, which isn't the same as coppicing, obviously, but cutting the same
size stems anyway.
I've been trying to figure out some way of developing a commericial
venture in the brush clearing aspect of native plant community restoration. A
lot of brush needs cutting, with not nearly enough manpower (usually all
volunteer, of course), and the brush is just piled and burnt. Seems like some
sort of small machine could be built to cut and chip the brush instead, but
probably the economics of it aren't there at this point. Such a machine might
well have a place in industrial coppicing, however. I've read something of very
large machinery for harvesting coppice, but I think something more family-sized
would be quite marketable, especially if a small family sized biomass pelletizer
were available.

--
Harmon Seaver
CyberShamanix
http://www.cybershamanix.com

From Carefreeland at AOL.COM Sat Mar 1 13:32:42 2003
From: Carefreeland at AOL.COM (Carefreeland@AOL.COM)
Date: Tue Aug 10 18:30:16 2004
Subject: Forwarding Ray W. on coppicing and Punchi Banda stove
Message-ID: <SAT.1.MAR.2003.133242.EST.>

In a message dated 3/1/03 11:56:14 AM Eastern Standard Time,
hseaver@CYBERSHAMANIX.COM writes:

DD Dan Dimiduk Writes
>
> These sound exactly like what is known hereabouts as "lobbers". Sold
> in
> probably just about every garden center, hardware store, etc.

DD Around here we call them Loppers. Professional strength ones available
from: A.M. Leonard Company @ www.amleo.com.
Can cut up to 2" or 5 cm diameter with larger ones according to the
manufacturer. With experience on soft wood you can cut much larger branches
with several cuts from different angles.

They cut cleanly > if sharp, but I'd think if you had much to harvest you'd
> be better off with a
> power brush saw, which has a circular sawblade, sort of the industrial
> version
> of a weedwacker. If you mean by "the damage to the cause of sustainability"
> the
> fact that they use fossil fuels, well that can quite easily be obviated by
> fueling them with ethanol. But a chain saw probably would be less desirable
> than
> a brush saw, for one because the chain tends to leave more ragged cuts in
> some
> species, and also because you have to bend over so much if you are cutting
> low.
> At least that's been my experience in clearing brush in prairie restoration
> projects, which isn't the same as coppicing, obviously, but cutting the
> same
> size stems anyway.
> I've been trying to figure out some way of developing a commericial
> venture in the brush clearing aspect of native plant community restoration.
> A
> lot of brush needs cutting, with not nearly enough manpower (usually all
> volunteer, of course), and the brush is just piled and burnt. Seems like
> some
> sort of small machine could be built to cut and chip the brush instead, but
> probably the economics of it aren't there at this point. Such a machine
> might
> well have a place in industrial coppicing, however. I've read something of
> very
> large machinery for harvesting coppice, but I think something more
> family-sized
> would be quite marketable, especially if a small family sized biomass
> pelletizer
> were available.
>
>
> --
> Harmon Seaver
> CyberShamanix
> http://www.cybershamanix.com
>
DD Again Harmon, when you think ahead of the curve, you can really hit the
nail on the head.

DD I am looking for contract woodlot clearing work for my 15" tree shear
and bobcat loader combination. I hope to burn 10-20% biodiesel, which is
gradually becoming available locally. The tree shear would make an excellent
tall stump cutter for trees which easily coppice from the stump. The shear
handles the tree as quick as a bucket load of soil or rock, clipping any tree
in it's jaws quicker than I can say it, just like a giant lopper. It also
grabs the tree to maneuver it into any position for farther cutting work or
loading.
DD Many of the local hardwoods grow back quickly from the stump. A
branched coppiced stump could be thinned at say 3"- 6" diameter, removing
only one trunk at a time. This would allow for a stronger regrowth from a
thriving stump. The smaller diameter logs would not need to be split as much
if at all, also saving labor. Labor is more of a concern here in the USA,
but not in the third world. I would expect several tons per acre annual
yield in this non-tropical environment.

DD I was comparing the stated price paid for hand cut fuel. At $.15
per kilo, that would be $136/ton equivalent. If one were to buy, air dry
seasoned firewood, locally here in Ohio USA, that price would correspond to a
delivered full cord. The only advantage of the firewood would be the large
percentage of hardwood would probably make this weigh in at 1&1/2
tons(1.short ton =2000 pounds or approx. 909 kilos) or more. When one takes
into account the quantity discount, the prices are quite in line. Small
bundles of sometimes only softwood sell for several dollars and can
correspond to almost $300/cord or more.

DD I believe that even in the somewhat wealthier segment of the Third World,
communities or businesses could invest in a good used 800 series Bobcat
loader for such uses. These are now becoming widely available in the USA as
contractors such as cement crews, upgrade and sell depreciated equipment into
a swollen used equipment market. The machines could also be used for
numerous other jobs, with many attachments available.

DD The tree shear does not use much power, and needs the weight of the
bigger machine for counter balance of treetop weight. These preowned 800
series with the smaller engines, would be ideal. I have seen many for sale,
worn but in good condition. Some sell for $10,000 or less, down to $5000 for
ones that need much service.

DD Most use Kobota Diesel engines. 46hp is one standard engine widely
available. The 56hp turbo diesel is also around in quantity. I'm sure that
any good biodiesel mix could be used as fuel. I would be interested in the
results of experimentation with pure biodiesel. Has anyone used biodiesel in
a Kabota turbodiesel?

DD The company I bought my shear from makes larger, but not smaller shears
than my 15." Someone could easily build a power shear that could cut say up
to 6" diameter trees with a small tractor. Just back up to the tree and
clip. Trees and shrubs of this size could be farther managed by hand from
there on, or bundled and dragged with the same tractor.
DD I am thinking of making a jaw for my shear which would allow for
extracting (pulling)honeysuckle shrubs, roots and all. Honeysuckle is a
nonnative invasive species which grows to say 30' and has a stump about 5" in
diameter max. I could also handle large poison Ivy this way.

DD There is no doubt that clipping, as opposed to cutting, is desired. It is
quicker, cleaner, and simpler to maintain the equipment.

Dan Dimiduk

From lanny at ROMAN.NET Sat Mar 1 23:40:05 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:16 2004
Subject: Camp Stove #6A Test
Message-ID: <SAT.1.MAR.2003.204005.0800.LANNY@ROMAN.NET>

I changed Camp Stove #6 by wrapping the pot sleeve with 4 plies of
fiberglass fabric and aluminum foil. I also wrapped the outer shell (the
bucket) with 2 plies of fiberglass fabric and one ply of foil.
I used 562 grams of wood (and had 53 grams of charcoal remaining) to bring 6
liters of 55degF=12.78 degC of water to a boil and hold the temp above
140degF=60 degC (minimum safe hot holding temp) for 3 hours and 15 min.
I am impressed with the stoves ability to hold heat after the fire is out.
More details at
Page two #6a test about 50 KB
http://www.lanny.us/cs6a.html

First page camp Stove #6 aprox 200KB
http://www.lanny.us/cs6.html

Lanny Henson

From psanders at ILSTU.EDU Mon Mar 3 23:38:14 2003
From: psanders at ILSTU.EDU (Paul S. Anderson)
Date: Tue Aug 10 18:30:16 2004
Subject: Forwarding Ray W. on coppicing and Punchi Banda stove
In-Reply-To: <NGBBKDEHILILFNJPHEFIOEFFCJAA.ronallarson@qwest.net>
Message-ID: <MON.3.MAR.2003.223814.0600.PSANDERS@ILSTU.EDU>

Ron and Ray and Tom,

At 07:26 AM 3/1/03 -0700, Ron Larson wrote:
>Stovers - Again I am forwarding with a few comments a valuable message from
>Ray W.
>.....snip...
>The current efforts of Punchi-banda are towards eliminating the auxiliary
>fan in his wood-gas stove...and using only natural ventillation. Most
>interesting results are evident. Initially, the flame is TOO strong
>resulting also in unburnt gasses... but about half-way through the cooking
>process it all levels out and thereafter only wood-gas burns with a blue
>flame. Very surprisingly the same quantity of wood now lasts longer and
>cooking times are thus extended; AND initial time to reach boiling is
>reduced. This is MOST surprising indeed. He is now working on better control
>of the burning initially (juggling the primary amd secondary air flows) and
>also better control of the heat of cooking (i.e. being able to achieve
>'simmering' when required).

Please explain how the blue flame is obtained, and also
please explain how this stove relates to (or is different from) the basics
of the IDD gasifier ala Reed-Larson. If it is the same basic technology,
what was the chain of information flow for the spread of the
innovation/technology?

Thanks,

Paul

> (RWL): I hope you can encourage Punchi-Banda to write us with
> these new
>results. For others, the P-B stove (seen at the Pune stove conference) has
>been rather like that of Tom Reed's (with a small fan, now apparently going
>out). When last heard, it was selling well in Sri Lanka. I have been
>urging P-B to produce charcoal in this stove - and cannot tell if that is
>happening.

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders

From crispin at NEWDAWN.SZ Tue Mar 4 02:55:46 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:16 2004
Subject: Is it Good to be Holey?? Re: [STOVES] Charcoal Briquetting
Machinery
Message-ID: <TUE.4.MAR.2003.095546.0200.CRISPIN@NEWDAWN.SZ>

Dear Richard

>We are observing use of 2 to 2.5, of the 125 gram holey briquetes is
>sufficient to replace 1.2 kg of fuel wood in the above domestic basic
>cooking situation.

This seems reasonable. Vivienne Abbott reports using 0.8 kg ofwood to cook
a meal in a Shisa stove (no free-running secondary air) compared with 3kg in
a three stone fire. If I extrapolate your figures then I get 6.25 holey
briquettes (high side figure) per equal meal cooked. That is about 780 gm
of briquette, or about equal to an improved stove burning wood.

The unknown there is the relative efficiency of the use of wood you report
and the use of wood in the three stone fire. They might have had a better
fire manager in Vivienne's tests.

The thing is, it shows that there is a chance to build a briquette that is
probably as efficient as a good improved stove. That is very interesting.
The only advantage left to achieve is to make the fire controllable. I have
mentioned before that the holey briquettes tend to burn with a lower heat in
the beginning and more later which is the opposite of our local cooking
requirements.

Perhaps we need to include a new type of stove in our lexicon: the biomass
stove - literally made of biomass.

Regards
Crispin

From crispin at NEWDAWN.SZ Tue Mar 4 02:57:34 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:16 2004
Subject: RE Is it Good to be Holey?? Re: [STOVES] Charcoal Briquetting
Machinery
Message-ID: <TUE.4.MAR.2003.095734.0200.CRISPIN@NEWDAWN.SZ>

Dear Kevin'n'All

All fair comment:

>Conventional wisdom says that holey briquettes of uncarbonized
>biomass are "better" than holey briquettes of the same material
>that is not holey.

[snip]

>The problem with dry biomass is that it is very easy to gasify and
>very difficult to burn to completion. Dry wood is a radically different
>fuel from wet wood. One can make a case that contrary to making
>briquettes with more surface area, one should be making briquettes
>with a combustion retardant, to slow the primary combustion process
>to the point that the secondary combustion process has a fighting
>chance of being brought to completion.

I am coming to the conclusion that in many stoves, without a method of
allowing in secondary air to do that job, things look pretty hopeless.
Unless you want the stove to run flat out, or you reduce the fuel (which is
the same thing as the reduced fuel still runs flat out) it is very difficult
to finish off the combustion, period.

This whole subject seems to be shaping up as a choice between a lab stove
and a practical one.

John Olsen wrote:
>>,,,,,The problem with dry biomass is that it is very easy to gasify
>>and very difficult to burn to completion,,,,
>I disagree, if the biomass is dried, as in our process to 8% moisture
>content, we achieve total burn.

I think, John, that he meant not the fuel as a potentially clean burning
product, but something related to a stove, in that it can be difficult to
get enough secondary air in to burn a relatively high volatility fuel, in
which class I place dung. For the same reasons, I find that cow dung gasses
at a lower temperature, or at least more easily, than wood.

I am suspicious that it might not be true, only that it appears to be.
Perhaps it is related more to high presented surface area than the nature of
the raw material. Not sure myself.

>1: Under what conditions is it good to be holey?

None I have found. It is best to break up the briquette and throw the
pieces into a Vesto.

>2: Where conditions are such that an increase in fuel surface area are
>advantageous, is there a better way to address these conditions than by
>making briquettes with holes?

Good question. If it ain't broke don't fix it.

Kevin wrote to John:

>It is simpler to make briquettes with no holes.

I agree. I have stopped puting holes in the Fire Cubes because it
unnecessarily complicated the equipment and they burn very well in the
stoves. If however, there is no stove and the briquette is burned alone,
the the hole is the combustion chamber.

I am back in Swaziland now and I will try to build a standard Rocket chamber
with preheated secondary air and a controlled primary supply added to bring
to the conference. I would appreciate some 'standard' dimensions being sent
to me.

Regards
Crispin

From lanny at ROMAN.NET Wed Mar 5 18:28:36 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: Camp Stove #6A Test #2 Cooking Rice
Message-ID: <WED.5.MAR.2003.152836.0800.LANNY@ROMAN.NET>

Stove Friends,
The web page aprox 125KB shows photos of a rice cooking test in the Camp
Stove #6A
http://www.lanny.us/rice.html
513 grams of wood and 6.5 grams of charcoal cooked 13 meals (cooked 1/2
liter) or 38 servings (cooked 3/4 cup = 177 ml) of brown rice which needs 45
min to cook.
I used:
1588 grams of brown rice =56 oz =2 QT volume=1.9 liter volume
4.7 liters of water
2 TBS =30 ml salt
50 ml oil
It took 513 grams of wood and 6.5 grams of charcoal to bring the 4.7 liters
of water, salt and oil to a boil (34 min). I added the 1.9 liters of rice,
which came to a boil 3 min. later. Then I shut down stove and caped the
exhaust
One hour later the temp was 182 degF and the rice was done.
There was about 6.5 liters of cooked rice which is 13 one half liter meals
or the rice cooking instructions said 38 -? cup (=177ml) servings.
So that is 39.5 grams of wood and .5g of charcoal per meal (1/2 liter)
Or less than 14 grams of wood per serving (? cup =177ml)
How much is 39.5 grams of wood? And 14 grams?
see photo 25KB http://www.lanny.us/rice4.jpg
Lanny Henson :-)

From tombreed at ATTBI.COM Wed Mar 5 12:31:06 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:17 2004
Subject: Punchi Banda Stove
Message-ID: <WED.5.MAR.2003.103106.0700.TOMBREED@ATTBI.COM>

Dear Paul, Ron, Ray and Punchi Banda:

I was very impressed with the Punchi Banda forced draft stove when I saw it
in Pune in 2000, and am not surprised that he is making progress. Some of
Ray's comments sound "to good to be true(something for nothing)" and my
mother warned me against such.

We have been operating natural draft stoves for 18 years and have had to
work hard to get blue flames. Paul has also made many natural draft
inverted downdraft stoves, excellent, but not as small/intense/good as
forced draft.

The world needs WoodGas stoves, and is not likely to compete with PB in SL.
I hope PB can send us more information on both his general work and sales in
SL, and we are happy to share our experience.

Yours for better cooking... TOM REED BEF STOVEWORKS

Dr. Thomas B. Reed
1810 Smith Rd., Golden, CO 80401
tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax
----- Original Message -----
From: "Paul S. Anderson" <psanders@ILSTU.EDU>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Monday, March 03, 2003 9:38 PM
Subject: Re: [STOVES] Forwarding Ray W. on coppicing and Punchi Banda stove

> Ron and Ray and Tom,
>
> At 07:26 AM 3/1/03 -0700, Ron Larson wrote:
> >Stovers - Again I am forwarding with a few comments a valuable message
from
> >Ray W.
> >.....snip...
> >The current efforts of Punchi-banda are towards eliminating the auxiliary
> >fan in his wood-gas stove...and using only natural ventillation. Most
> >interesting results are evident. Initially, the flame is TOO strong
> >resulting also in unburnt gasses... but about half-way through the
cooking
> >process it all levels out and thereafter only wood-gas burns with a blue
> >flame. Very surprisingly the same quantity of wood now lasts longer and
> >cooking times are thus extended; AND initial time to reach boiling is
> >reduced. This is MOST surprising indeed. He is now working on better
control
> >of the burning initially (juggling the primary amd secondary air flows)
and
> >also better control of the heat of cooking (i.e. being able to achieve
> >'simmering' when required).
>
> Please explain how the blue flame is obtained, and also
> please explain how this stove relates to (or is different from) the basics
> of the IDD gasifier ala Reed-Larson. If it is the same basic technology,
> what was the chain of information flow for the spread of the
> innovation/technology?
>
> Thanks,
>
> Paul
>
> > (RWL): I hope you can encourage Punchi-Banda to write us with
> > these new
> >results. For others, the P-B stove (seen at the Pune stove conference)
has
> >been rather like that of Tom Reed's (with a small fan, now apparently
going
> >out). When last heard, it was selling well in Sri Lanka. I have been
> >urging P-B to produce charcoal in this stove - and cannot tell if that is
> >happening.
>
> Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
> Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
> Dept of Geography - Geology (Box 4400), Illinois State University
> Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
> E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
>

From elk at WANANCHI.COM Thu Mar 6 00:16:06 2003
From: elk at WANANCHI.COM (elk)
Date: Tue Aug 10 18:30:17 2004
Subject: Camp Stove #6A Test #2 Cooking Rice
Message-ID: <THU.6.MAR.2003.081606.0300.ELK@WANANCHI.COM>

I like it Lanny!

Your stove #6A seems to be approaching the upper boundaries of efficiency,
and I think that the rice cooking test is a very good practical method for
efficiency comparison. 39 grams of wood (140 kcal) per meal isn't much fuel.
If we can all agree on the properties of cooked (v.s. under or over-cooked)
rice, then this approach has the potential to allow list members who rarely
meet to compare their stoves.

A question to all list members: Aside from rice, is there any other commonly
available item that would provide a 'litmus test' for stove efficiency?
Something that would suddenly change colour, fall apart or go into solution
after a specific amount of energy input in boiling water? Rice will probably
do, but there just might be something that eliminates the subjectivity on
the definition of 'cooked' and any variation due to rice type.

elk

--------------------------
Elsen L. Karstad
elk@wananchi.com
www.chardust.com
Nairobi Kenya

----- Original Message -----
From: "Lanny Henson" <lanny@ROMAN.NET>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Thursday, March 06, 2003 2:28 AM
Subject: [STOVES] Camp Stove #6A Test #2 Cooking Rice

From ronallarson at QWEST.NET Thu Mar 6 02:07:13 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:17 2004
Subject: Camp Stove #6A Test #2 Cooking Rice
In-Reply-To: <003501c2e39f$7fef7560$1d41083e@42v2501>
Message-ID: <THU.6.MAR.2003.000713.0700.RONALLARSON@QWEST.NET>

Elsen, Lanny, et al

1. Lanny's use of a chimney enables him to totally stop air flow and
achieve the nice sealed conditions which gives the "haybox" effect. A big
savings is coming from having a (closeable) chimney - and I don't ever
remember hearing/seeing that before. I guess a strong argument for a
chimney over a hood or neither. Note he is getting better draft than most
stoves - and is getting a shorter stove body by having a spiral flame path.
Lots of nice ideas coming along here.

2. Lanny is getting a good bit of his efficiency improvement (and the low
heat loss during the "haybox" period) from his tight fitting "convection
sleeve" and then a downdraft outer section. I would like to hear how much
his temperature would have changed with or without additiponal outer layers
of insulation (which I don't see reported here). Others can't achieve the
same tight fitting character as they are venting above/past the pot.
Lanny - how much of the cook pot was exposed above the stove itself? Any
insulation placed above the pot lid in this test?

3. I sure don't know of any food that can be cooked the way Elsen is
hoping for. We are probably stuck with a boiling-away test - and hope that
Lanny can report on any such tests he may have performed that old-fashioned
way.

4. Lanny - your photo-journalism is getting pretty professional also!!
Nice job.

Ron

>-----Original Message-----
>From: The Stoves Discussion List [mailto:STOVES@LISTSERV.REPP.ORG]On
>Behalf Of elk
>Sent: Wednesday, March 05, 2003 10:16 PM
>To: STOVES@LISTSERV.REPP.ORG
>Subject: Re: [STOVES] Camp Stove #6A Test #2 Cooking Rice
>
>
>I like it Lanny!
>
>Your stove #6A seems to be approaching the upper boundaries of efficiency,
>and I think that the rice cooking test is a very good practical method for
>efficiency comparison. 39 grams of wood (140 kcal) per meal isn't
>much fuel.
>If we can all agree on the properties of cooked (v.s. under or over-cooked)
>rice, then this approach has the potential to allow list members who rarely
>meet to compare their stoves.
>
>A question to all list members: Aside from rice, is there any
>other commonly
>available item that would provide a 'litmus test' for stove efficiency?
>Something that would suddenly change colour, fall apart or go into solution
>after a specific amount of energy input in boiling water? Rice
>will probably
>do, but there just might be something that eliminates the subjectivity on
>the definition of 'cooked' and any variation due to rice type.
>
>elk
>
>
>--------------------------
>Elsen L. Karstad
>elk@wananchi.com
>www.chardust.com
>Nairobi Kenya
>
>
>
>----- Original Message -----
>From: "Lanny Henson" <lanny@ROMAN.NET>
>To: <STOVES@LISTSERV.REPP.ORG>
>Sent: Thursday, March 06, 2003 2:28 AM
>Subject: [STOVES] Camp Stove #6A Test #2 Cooking Rice
>
>
>Stove Friends,
>The web page aprox 125KB shows photos of a rice cooking test in the Camp
>Stove #6A
>http://www.lanny.us/rice.html
>513 grams of wood and 6.5 grams of charcoal cooked 13 meals (cooked 1/2
>liter) or 38 servings (cooked 3/4 cup = 177 ml) of brown rice
>which needs 45
>min to cook.
>I used:
>1588 grams of brown rice =56 oz =2 QT volume=1.9 liter volume
>4.7 liters of water
>2 TBS =30 ml salt
>50 ml oil
>It took 513 grams of wood and 6.5 grams of charcoal to bring the 4.7 liters
>of water, salt and oil to a boil (34 min). I added the 1.9 liters of rice,
>which came to a boil 3 min. later. Then I shut down stove and caped the
>exhaust
>One hour later the temp was 182 degF and the rice was done.
>There was about 6.5 liters of cooked rice which is 13 one half liter meals
>or the rice cooking instructions said 38 -? cup (=177ml) servings.
>So that is 39.5 grams of wood and .5g of charcoal per meal (1/2 liter)
>Or less than 14 grams of wood per serving (? cup =177ml)
>How much is 39.5 grams of wood? And 14 grams?
>see photo 25KB http://www.lanny.us/rice4.jpg
>Lanny Henson :-)
>
>

From crispin at NEWDAWN.SZ Thu Mar 6 04:03:07 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:17 2004
Subject: Camp Stove #6A Test #2 Cooking Rice
Message-ID: <THU.6.MAR.2003.110307.0200.CRISPIN@NEWDAWN.SZ>

Dear Elk and Lanny

I did some quick calculations yesterday to see what work is being done and
when. I don't want to be a damp squib but I don't think the efficiency is
all that high. In got a figure of less than 30% but am wide open to
correction. Please provide figures.

I worked on how much time it took and how much fuel I thought was used by
the time it boiled. Rice does not need to be boiled to cook so the results
can be misleading. There is still info missing in the report to know
exactly.

It took 34 minutes to boil 4.7 litres of water (temps not given) and the
fire was 'shut down' after that, I assume it means the fire was put out over
the next few minutes and things carried on cooking using retained heat in
the pot, the stove and the water.

I have a Hot Bag at home which I use to cook rice. I boil the water and
throw in the rice, then after the boil is reached again I put the whole pot
into the bag and tie it shut. No additional fuel is used to 'cook' the
rice.

For this reason I am not sure if rice is a good test medium. You can cook
rice in very warm water if you wait long enough.

From lanny at ROMAN.NET Thu Mar 6 20:34:19 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: Tariq Javed from Pakistan
Message-ID: <THU.6.MAR.2003.173419.0800.LANNY@ROMAN.NET>

Dear stove friends,
I got two notes from a very interesting person from Pakistan. He said that
it is OK to pass them along.
Tariq also ask to be added to the Stove List.
I have combined his notes.

<Dear Lanny,
thank you for your e.mail and we are interested if you will pass comments.
kindly include us in your stove list.My official address and e.mail is as
follow.
Mr. Tariq Javed
National Coordinator
Agriculture & Environment
Caritas Pakistan
23/3 Race Course Road Lahore-Pakistan
Tel: 92-42-6315584-5
Email:caritas@brain.net.pk
<
<Dear Lanny,
Greetings from Pakistan!
please be informed that i Tariq Javed working on fuel-efficient stove from 2
years. i got your e.mail from Bertile Charles. i launhed the fuel-efficient
stove program in Pakistan in 30 villages and achieved the big target. we
have also lauched the bimass study in 10 villages of pakistan which is under
process. I believed that the fuel-efficient stove reduces the 50% wood
consumption as a fuel as compared to tradtional stove of Pakistan and at the
time 50 % time saving of the women which do cooking for the family. this
stove has two stoves and one gate for the burning of wood. it has the chmney
through which the smoke goes out of the kitchen it has also the damper by
which we could control the heat.

i presented the model in the Asia Regional Workshop in the Philippines.

with best wishes and warm regards
Tariq Javed
National Coordinator
Agriculture & Environment
Caritas Pakistan
23/3 Race Course Road
Lahore-Pakistan.
Tel; 92-42-6315584-5
e-mail: tariqjk@hotmail.com
caritas@brain.net.pk
<

From lanny at ROMAN.NET Fri Mar 7 10:33:31 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: Camp Stove #6A Test #2 Cooking Rice
Message-ID: <FRI.7.MAR.2003.073331.0800.LANNY@ROMAN.NET>

Elk, Ron, Crispin,
Thanks for your comments.
I will answer some questions and comment more later.

Elk said-I like it Lanny! Your stove #6A seems to be approaching the upper
boundaries of efficiency,
and I think that the rice cooking test is a very good practical method for
efficiency comparison. 39 grams of wood (140 kcal) per meal isn't much fuel.
If we can all agree on the properties of cooked (v.s. under or over-cooked)
rice, then this approach has the potential to allow list members who rarely
meet to compare their stoves.

LH- Thanks, The heat transfer to the pot and the hay box effect are good
but the combustion efficiency needs work.
The rice cooking test may be a good thing but I hope you like eating a lot
of rice!

RON-Lanny - how much of the cook pot was exposed above the stove itself?
Any
insulation placed above the pot lid in this test?

LH- The pot is 8.5" (21.6 cm) in diameter and 8" (20.3 cm) tall. It is
sunken 6" (15.2 cm) and 2" (5.1 cm) is exposed above the stove. That is
about 216 sq in of surface area to collect heat.
No insulation was placed on the lid but maybe I should.

Crispin said
I did some quick calculations yesterday to see what work is being done and
when. I don't want to be a damp squib
(LH- Truth rules)
but I don't think the efficiency is
all that high. In got a figure of less than 30% but am wide open to
correction. Please provide figures.
For the moment I would prefer to have a boiling test of a known quantity of
water with the mass of the pot given, plus the material it is made from.
Also needed are the type of fuel, moisture content and amount consumed.

LH- I will fill in the blanks next time if there is a next time. It may take
me 6 months to eat all that dam* rice. I think I will stick to cooking water
like you said :-)
Lanny Henson

From ronallarson at QWEST.NET Fri Mar 7 09:41:15 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:17 2004
Subject: [ethos] Re: char/clay
In-Reply-To: <005e01c2e4fb$36b5bf00$c91e6c0c@default>
Message-ID: <FRI.7.MAR.2003.074115.0700.RONALLARSON@QWEST.NET>

Dean and Richard:

A few comments and more questions:

1. I had forgotten this recommendation on a charcoal-clay mix from Richard.
I found it at http://www.repp.org/discussion/stoves/200006/msg00030.html

I kick myself for not having tried it myself earlier. Thanks to Dean for
bringing this back up.

2. To add to the nice things Dean said, Richard is a retired Ceramics
Professor at Crowder College in Neosho, Missouri - who lives pretty far out
in a beautiful rustic setting. As Dean said, he is an inventor as well as
potter. His son is also a Professor at Crowder - which put in a very
competitive (6th out of 14) entry into the recent Solar Decathlon
Competition, with his son as faculty adviser. The College also has worked
on and successfully competed in solar car races. This must be a very
special College, as it is very small (maybe 2 year?) Going back in our
stoves archives, you will find Richard describing and further developing
charcoal-making stoves (he called "ten-can" I think) - which were works of
art.

3. I'd like to know more about the strength and density after firing?
Floatable?

4. And the details of firing? About what temperature? How fast in coming
up to temperature?
(I ask because, for potters, any biomass in clay can cause "bloating". At
a certain temperature the charcoal will start disappearing but these gases
can escape (without bloating) if the temperature rise is done slowly
enough.)

5. Dean - when you say you fired it in the Rocket - could you describe this
more completely? The size of the tile, how suspended, how long for the
firing, can you fire more than one at a time, etc?

6. Have you tried yet the stucco idea? What thickness were you
considering? This could allow the use of some cheaper and thinner metals -
maybe even Aluminum?

7. Would it be easy to fire with holes - as Crispin is recommending?

8. I think this approach could have excellent potential for many stoves,
and am anxious to hear more from Richard and Dean. Right at the end of his
June 2000 message, Richard alluded to something better that was in the
works. I hope he can tell us more now.

Ron

>-----Original Message-----
>From: owner-ethos@vrac.iastate.edu
>[mailto:owner-ethos@vrac.iastate.edu]On Behalf Of Dean Still
>Sent: Friday, March 07, 2003 3:45 PM
>To: jeremy foster; ethos; Richard Boyt; Grant Ballard-Tremeer;
>STOVES@LISTSERV.REPP.ORG; ken goyer; damon ogle
>Subject: [ethos] Re: char/clay
>
>
>Dear Jeremy,
>
>Using charcoal and clay as a insulative stucco (in this application on the
>tunnel walls of the Lorena earthen stove) has been mentioned before, by
>Richard Boyt: a thoughtful STOVES contributor, stove inventor, artist and
>good friend of Larry and mine. In June, 2000 he said",
>
>
> Early testing suggests the advantages of combining
>a slurry of common clay, various sizes of graded
>charcoal particles, and water into a consistency much
>like that of a concrete mix of sand, gravel, cement,
>and water. When wet, the mix can be molded or cast to
>shape, and upon drying becomes fairly rigid and
>remains so at temperatures exceeding red heat. The
>clay serves to coat the char particles, excluding air
>and preventing its oxidation.
>
> Admittedly, the insulative performance of this
>char/clay mix does not compare favorably with
>relatively expensive, commercial hi-temp insulations
>such as vermiculite, blankets of spun alumina or
>silica, and soft, light weight brick. However, while I
>must buy any of these, I can sift for free char from
>the ashes of our wood burning heating stove and I can
>dig clay from the ground less than 100 feet from our
>back door.
>
> Different mixes of clay and char produce different
>insulative and weight properties. More clay makes for
>more weight and less insulation. Different
>combinations of char particles pack a space more or
>less completely. Different clays shrink more or less
>forming larger or smaller cracks to be filled."
>
>I find charcoal clay to be sticky and I do think that it might work in this
>application as an insulative coating. I'll continue testing. The
>sample tile
>I like best is 15% clay to 85% finely ground charcoal. Graded mixes would
>make lighter and better tiles. After being fired in the Rocket
>stove the mix
>turns from black to mostly white. The core remains black.
>
>All Best,
>
>Dean
>
>
>
>
>

From crispin at NEWDAWN.SZ Fri Mar 7 23:59:15 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:17 2004
Subject: RE Camp Stove #6A Test #2 Cooking Rice
Message-ID: <SAT.8.MAR.2003.065915.0200.CRISPIN@NEWDAWN.SZ>

Dear Lanny

>>For the moment I would prefer to have a boiling test of a
>>known quantity of water with the mass of the pot given, plus
>>the material it is made from. Also needed are the type of fuel,
>>moisture content and amount consumed.

>LH- I will fill in the blanks next time if there is a next time.

OK. Good, if you can manage it. I am always interested in being able to
make close comparisons in real cooking. It provokes me to think harder
about what I can do to make improvements and useful suggestions.

I wanted to point out that rice also comes in different varieties and they
cook differently, and in my kitchen, people have different decisions about
when it is cooked. It is difficult to judge the stove alone from a
distance. Cooking rice is a sexy demo but we need numbers.

I think you have a lot of collection area and as long as the pot is
available it is a stove pot combination that is about optimised.

From lanny at ROMAN.NET Sat Mar 8 13:11:12 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: RE Camp Stove #6A Test #2 Cooking Rice
Message-ID: <SAT.8.MAR.2003.101112.0800.LANNY@ROMAN.NET>

Dear Crispin,

----- Original Message -----
From: Crispin <crispin@newdawn.sz>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Friday, March 07, 2003 8:59 PM
Subject: [STOVES] RE Camp Stove #6A Test #2 Cooking Rice

> Dear Lanny
>
> >>For the moment I would prefer to have a boiling test of a
> >>known quantity of water with the mass of the pot given, plus
> >>the material it is made from. Also needed are the type of fuel,
> >>moisture content and amount consumed.
>
> >LH- I will fill in the blanks next time if there is a next time.
>
> OK. Good, if you can manage it. I am always interested in being able to
> make close comparisons in real cooking. It provokes me to think harder
> about what I can do to make improvements and useful suggestions.
>
> I wanted to point out that rice also comes in different varieties and they
> cook differently, and in my kitchen, people have different decisions about
> when it is cooked. It is difficult to judge the stove alone from a
> distance. Cooking rice is a sexy demo but we need numbers.

LH- A boiling test is the same as a cooking test with the Camp Stove because
of its heat holding abilities. 6 liters of water is still hot enough to cook
at 1.5 hours later.
(1 hour and 37 min later the water temp was 175 degf.- 79.5 degC) which
should be long enough to cook most foods.

> I think you have a lot of collection area and as long as the pot is
> available it is a stove pot combination that is about optimised.

LH-Matching a pot to a stove could be a big problem for the sunken pot stove
design.

> From a general structural point of view, though it is hard to tell from
the
> pictures, I think there isn't enough vertical space in the stove to get a
> good flame that finishes burning between the fuel and the pot's bottom.
It
> just seems to be too short. I am thinking 'quenching' and avoiding that
> will bring the efficiency up. How does the flame look (height-wise) when
> you are bringing things to a boil?

LH- The chimney creates enough draft to have a horizontal flame path which
is about 12" to 14" long (30 to 36 cm).
I can't see the flame because when you pull out the pot it changes the
draft. I just look for clear exhaust.

>The power rating is quite low (1 kw?)
> and perhaps the flames are small?? The stoves I work with will boil 4.7
> litres of water in an aluminum pot in 13 or 14 minutes which is a
different realm.

LH- My strategy is to use a small hot fire and allow more time for the heat
to conduct into the pot. I can do that because of the insulated pot sleeve.
I am thinking that most uses of the stove would be in the 2 or 3 liter range
which should not take that long to boil.

LH- What volume would be cooked in a typical household in your area?

> Perhaps I should try building a very small fire intending to take 30
minutes
> or so and seeing if the efficiency rises significantly enough to interest
> cooks. It could be a productive approach in fuel-scarce environments, as
> long as the additional heat losses don't start taxing things.
>
> I know that using charcoal will slow things down and perhaps raise
> efficiency. One of the Solco staff from Pretoria cooked for 12 hours last
> weekend at a festival making tea and rice+veg. He used 4 kg of charcoal
in
> that time. The stove was a Shisa (no free-to-draw secondary air) with a
> single air control. Clearly the power rating was down. It was top loaded
> and bottom lit, refuelled every 45-60 minutes about 1/3 of the chamber
> volume. The flames are short in that condition.
>
> Have you tried cooking with charcoal only? You might get a surprise.

LH- Charcoal alone does not work that well in the Camp Stove. It is a stick
burner.
Thanks for your questions and comments.

Lanny Henson in Rome, Georgia USA

> Cook on!
> Crispin in Ezulwini
>

From crispin at NEWDAWN.SZ Sat Mar 8 11:43:05 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:17 2004
Subject: RE Camp Stove #6A Test #2 Cooking Rice
Message-ID: <SAT.8.MAR.2003.184305.0200.CRISPIN@NEWDAWN.SZ>

Dear Lanny

>LH- A boiling test is the same as a cooking test with the Camp
>Stove because of its heat holding abilities. 6 liters of water is
>still hot enough to cook at 1.5 hours later.

I think it is a very interesting and innovative approach. Have you worked
out how much heat is held in the stove after the fire is out? It there a
significant amount of retained heat or is it basically the insulation taht
'preserves' the heat in the pot?

>LH-Matching a pot to a stove could be a big problem for the sunken pot
>stove design.

It is a major problem 'in the field'. You can build a stove to match a
certain pot and find out that no one can find that same pot. With the solar
stoves sold by SolCo in Pretoria (a GTZ project) you are given a pot with
the stove for that reason. I have considered it and it is on the gaenda
with the Vesto. Because we think we are going to be able to sell quite a
number, we are going to talk to the pot manufacturers to make a pot with
handles that are suitable for sunken pot stoves.

>LH- The chimney creates enough draft to have a horizontal
>flame path which is about 12" to 14" long (30 to 36 cm).
>I can't see the flame because when you pull out the pot it
>changes the draft. I just look for clear exhaust.

OK. What do you adjust?

>LH- My strategy is to use a small hot fire and allow more time
>for the heat to conduct into the pot.

If you do that I figure you can get very efficient heat transfer at the cost
of time. Where time is not important and fuel is expensive, I think people
would go for such a device.

>I can do that because of the insulated pot sleeve.

What cost do you think the sleeve has? Dollars.

>LH- What volume would be cooked in a typical household in
>your area?

A lot of homestead use a 4 imperial gallon three legged pot for cooking the
starch and a 1.5 or 2 to cook the relish/meat. They are about 2/3 full I
think. We had to raise the top deck on which the pots sit to accomodate the
#4 which costs in heat transfer but increases variability of pot. The heat
available is adequate for a #4.

>LH- Charcoal alone does not work that well in the Camp Stove.
>It is a stick burner.

That is interesting. I am surprised. Any idea why it is not so good? Too
much draft?

Sincerely
Crispin

From lanny at ROMAN.NET Sat Mar 8 14:51:06 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: Test #3 - Camp Stove #6A
Message-ID: <SAT.8.MAR.2003.115106.0800.LANNY@ROMAN.NET>

Test #3 - Camp Stove #6A
http://www.lanny.us/cs6aa.jpg 36 KB photo
Fuel efficiency test- Bring 6 liters of water boil.
1- Fuel used- (352 grams of wood) It took 340 grams of pallet oak wood and 8
grams of charcoal. I will count 8 grams of charcoal as12 grams of wood to =
352 grams of wood.
2- Energy used- (5037.5 btu) Pardon my switch to the American system. 352
grams =.775 lb x 6500 btu per pound of air dry wood = 5037.5 btu used.

I am using 6500 btu per pound of air dry wood. Does that sound about right?
How many cal or joule in a typical gram or kg of air dry wood? and I will
get metric!

3- Energy needed for 100% efficiency (2072.4 btu) (6 liters at 2.2 lb =13.2
lbs X 157 degF temp rise (212-55 degF start temp) = 2072.4 btu

4- Efficiency = (41.1%) Energy used 5037.5 btu / energy needed 2072.4 =
41.1%
Please correct this.

5- Time to boil 30 min
6- Weather- very good -calm and cool
7- Pot- steel stockpot

Lanny Henson
http://www.lanny.us/

From crispin at NEWDAWN.SZ Sat Mar 8 14:43:44 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:17 2004
Subject: Test #3 - Camp Stove #6A
Message-ID: <SAT.8.MAR.2003.214344.0200.CRISPIN@NEWDAWN.SZ>

Dear Lanny

>Fuel efficiency test- Bring 6 liters of water boil.
>1- Fuel used = 352 grams of wood.
>2- Energy used = 5037.5 btu used.

>I am using 6500 btu per pound of air dry wood.

CPP: I would use 6883 as my 'normal' which is 16 MJ/Kg (I use a higher
number only for pine). I would calculate that you used 5.632 MJ = 5342 BTU
(the conversion factor is 948.45)

>3- Energy needed for 100% efficiency = 2072.4 btu

CPP: I get 2.2046x6 = 13.228 pounds of water x (212-55) = 2077 BTU plus the
heat in the mass of the pot and I count it as 212-55 in your case.

I don't count the stove's mass although a purist might ask you to as you are
using it to store heat to recover later with which to cook. Doing that also
gives you a theoretical problem which is that if you were asked to cook
continuously you couldn't recover the heat stored in the stove and it would
eventually be lost to the environment. That is why I don't want to use a
started and stopped stove when rating them because it is a vaguely
acceptable method of cheating in the cooking of one actual meal in a single
pot. Your 'cooking efficiency' would suffer if you had to cook two or more
pots in a row.

>4- Efficiency = (41.1%) Energy used 5037.5 btu / energy needed 2072.4 =
41.1%

CPP: I get 2077/5342= 38.9% but it is actually a little higher than that
because there is a bit of heat in the pot (I need the empty pot mass). It
isn't as much as you might imagine but if you are keeping 4 significant
digits, you might as well factor it in.

>5- Time to boil 30 min

CPP: This is then an average fuel consumption of 5342 BTU/30 = 178
BTU/minute or 352/30 = 11.73 gm per minute. I think that it is a useable
heat on the lower end of what I seek. I like the range of 10-25 gm/minute
of wood as as a stove's consumption. No matter. What you have is pretty
good.

Now... this is quite a bit better than your previous effort which you
reported as using 4.7 litres of water (plus a little salt and oil) and it
look longer to heat to a boil. I calculated that as follows:

523 gm (equivalent) of wood = 7937 BTU heating 10.36 pounds of water in 34
minutes
or (10.36*(212-55))/7937 = 20.5% efficiency. It was actually higher than
that for two reasons: you heated the pot as well, and you continued to boil
for 3 minutes but you didn't report the loss of water to steam during that
time (if any). That can be significant.

How much wood was left over? Was it 523 gm (equivalent) that was consumed?
I presumed so in that calculation.

So...what was different about this latest test? Was it, for example, a more
'wide open' test? The efficiency is very much higher higher. I am not
surprised as there was less time to lose heat to the environment. But it is
a very significant different. What do you think? Did you realize how much
better is it this time round? Whatever you changed it was a 'good thing'.
Was there less wood loaded in it so it could breathe better?

I think you should try loading it with low loads to see if the efficiency
goes up. If it does, you should look into the amount of secondary air
available. When it is loaded with more wood it is probably stifling it in
some way.

Regards
Crispin

From ronallarson at QWEST.NET Sat Mar 8 15:18:32 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:17 2004
Subject: Comments re Crispin reply to Lanny of March 8
In-Reply-To: <001a01c2e591$cf570340$1a04fea9@home>
Message-ID: <SAT.8.MAR.2003.131832.0700.RONALLARSON@QWEST.NET>

Some added comments - mostly on pots

froim today
<snip>

1.
>>LH-Matching a pot to a stove could be a big problem for the sunken pot
>>stove design.
>
Crispin: >It is a major problem 'in the field'. You can build a stove to
match a
>certain pot and find out that no one can find that same pot. With
>the solar
>stoves sold by SolCo in Pretoria (a GTZ project) you are given a pot with
>the stove for that reason. I have considered it and it is on the agenda
>with the Vesto. Because we think we are going to be able to sell quite a
>number, we are going to talk to the pot manufacturers to make a pot with
>handles that are suitable for sunken pot stoves.

(RWL1): Few more thoughts along this line:

1.a. Dean Still recently showed some pictures on the Ethos site of an
adjustable sleeve that allowed one to test various gap widths. Dean -
could you send interested parties to a web site and also say a bit more on
what you may have learned with that very clever looking device?

1b. I recently bought some high priced "West Bend" cooking utensils -
because of the superiority claims. I still haven't done any testing - but
here are some of the reasons for deciding to buy:

1. A lip for good sealing between pots and the top.
b. Adjustable "whistling-jiggling" vent on cover - that warns when
temperature is near boiling. Claimed to have much healthier food when
cooked at lower temperature - so like Lanny - they recommend removing from
the heat and slow cooking. They also recommend a "haybox" (or pillow). No
claim here on energy - just health - but energy aspects have to be good as
well.
c. A flat pot top - so that foods can be stacked one above another for
cooking. They claim only a few degrees loss from bottom to top (3-4 stacked
pots)
d. The above possible because of the highly conductive (multiple layers)
for all parts, tops, bottoms and walls. They have very flat surfaces.
Inner/outer surfaces all highly polished stainless. I think interior
materials are copper.. They warn against aluminum and iron.
e. Interchangeability of components for stacking.

1c. Some of these ideas (and even better?) are seen in what the Karves are
doing in Pune - again with vertical stacking. Their stainless cookpot is
both tall and comes with built-in sleeve (presumably of close to optimum gap
width.

1d. On "Stoves", we have periodically talked about the benefits of the
Russian Samovar design. I believe that cook pots with an interior "chimney"
could be effective - and would like to see if Crispin's pot makers could
develop such. All (?) US gas water heaters are built this way. May not be
right for cooking food - as one needs a tall unit for maximum heat transfer.
But for some really large families/kitchens this might give some good
efficiencies.

1e. I like the idea of a pot - stove combination. Dropping the pot further
into the convection sleevve must be helpful - and we can work toward an
optimum gap width.

2.
>>LH- The chimney creates enough draft to have a horizontal
>>flame path which is about 12" to 14" long (30 to 36 cm).
>>I can't see the flame because when you pull out the pot it
>>changes the draft. I just look for clear exhaust.
>
(RWL2) <snip>
How much soot buildup are you getting on the bottoms of the embedded cook
pots? Have you any easy way to vary this path length. If we thought of the
arc path as a helix - what would be the pitch? Can you tell us more about
the importance of the arc approach in your design?

> 3.
>>I can do that because of the insulated pot sleeve.

(RWL3): Lanny. I think it important to note that hot air is flowing on
both sides of your pot sleeve (up on inside - down on outside) - so the
insulation is necessarily farther out and not necessarily always there. Can
you report on what happens as a function of this outer insulation? I think
you are still the only one doing this downward flow of exhaust gases -
possible because you have a chimney (which looks very short in this last
photo. Did you normally have an added section of chimney?

<snip>
4.
>>LH- Charcoal alone does not work that well in the Camp Stove.
>>It is a stick burner.
>
>That is interesting. I am surprised. Any idea why it is not so good? Too
>much draft?
>
(RWL4): I am not surprised that the stove doesn't work well with charcoal.
I am interested in knowing how good the Vesto is in consuming charcoal. I
am not aware of any wood-burner that works well also with charcoal. Some
stoves designed for charcoal can be used with wood - but I think are not
very efficient or clean. I hope Crispin can describe the efficiency
differences in performance if he started with a full load of charcoal - and
any reasons for similar performance.

Regards Ron

>Sincerely
>Crispin
>
>

From crispin at NEWDAWN.SZ Sat Mar 8 16:14:44 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:17 2004
Subject: Comments re Crispin reply to Lanny of March 8
Message-ID: <SAT.8.MAR.2003.231444.0200.CRISPIN@NEWDAWN.SZ>

Dear Ron

Not too much to add here:
>1.a. Dean Still recently showed some pictures on the Ethos site of
>an adjustable sleeve that allowed one to test various gap widths.

I also think this is a good idea and I hope to do it in 0.5mm bright
polished 409 stainless steel which is pretty cheap and it actually available
as off cuts - the shields are not very big. I found a coil of it last week
for the next 50 units. I hope they will be ready by Friday even though I
won't be there to assist. We are starting the marketing survey, but without
the livery on the can which is still plain black.

>c. A flat pot top - so that foods can be stacked

I once had a guy home-demo a set like for some vast cost. The stack works
like a series of heat pipes, as I understand it. There is boiling on the
bottom and condensation on the top. He cooked a meal on one element with 4
pots.

d. ...I think interior materials are copper

I am really sure they are 304 stainless steel. You pretty much can't cook
in copper any more. It's a heavy metal.

>...They warn against aluminum and iron.

Iron?? As in cast iron?

>1e. I like the idea of a pot - stove combination. Dropping the pot
>further into the convection sleevve must be helpful - and we can
>work toward an optimum gap width.

I think there is a future in that. Something adjustable, stackable, modular
to suit known pots.

>(RWL4): I am not surprised that the stove doesn't work well with
>charcoal. I am interested in knowing how good the Vesto is in
>consuming charcoal.

I already reported what the GTZ stove demonstrator said about his experience
last weekend with the Shisa stove. Cecil Cook's garlic growers also
reported very long cooking times unattended - like 4 to 5 hours - on a
single charge in a Tsotso. I was dubious but now am taking the claims more
seriously. It must be a low heat and have a very high transfer rate. It is
equivalent to burning about 8 and a half grams of wood per minute. That is
pretty low but the efficiency of combustion would have been very high, and
with a low stack velocity the transfer must have been tremendous. I haven't
done boiling tests with charcoal as it costs $ and there is so much wood
around.

>I am not aware of any wood-burner that works well also with charcoal.

I was not aware that it would be an issue. Other than the fact that the
charcoal tends to be closer to the pot bottom, what's the difference? If
the heat is contained in a long insulated chamber (by air or materials) it
can rise to the pot. The Vesto has a 325mm deep combustion chamber and that
is enough space to burn wood or charcoal if the load is kept at 200mm or
less. Maybe 220.

>...describe the efficiency differences in performance

Perhaps we can test that at the conference. I understand we are going to be
doing practicals in Vereeniging.

I am going to scrounge around for some old stoves so people can see what we
found here and there. There are some dreadful things made of clay collected
from around Africa stored at the Luyengo campus of the University of
Swaziland. I'll leave them. I'm pretty sure I have a David Hancock original
Tsotso in working condition, or at least a heavier copy of it.

Do you know there isn't a single clay stove in Africa with metal parts that
are part of the combustion cycle? There is the Jiko with a metal frame and
a clay liner, but none of them have steel parts inside to improve secondary
air provision. A surprise really. I think a clay stove with a Tsotso
basket grate would burn dung very well. Maybe I can drag some parts out as
well to use the clay stove people's experience at the conf. Remember when
Paul A and I were talking about sending grates to Afghanistan? That was to
do exactly that. Perhaps the Jiko would work better with wood and charcoal
if it had the steel parts on the inside and the clay on the outside! We
could call it a Kijo.

Stay well!
Crispin

From dstill at EPUD.NET Sun Mar 9 00:08:40 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:17 2004
Subject: Comments re Crispin reply to Lanny of March 8
Message-ID: <SAT.8.MAR.2003.210840.0800.DSTILL@EPUD.NET>

Dear Friends,

Ron asks:

>1.a. Dean Still recently showed some pictures on the Ethos site of an
>adjustable sleeve (pot skirt) that allowed one to test various gap widths.
Dean -
>could you send interested parties to a web site and also say a bit more on
>what you may have learned with that very clever looking device?

The photos should soon be posted on STOVES and HEDON, I think... One of
Larry Winiarski's tried and true rules of thumb for stove design is: The gap
between the pot and skirt should be about the same cross sectional area as
is allowed for the flow of heat through the stove, i.e., the same as the
combustion chamber, etc. For large pots this means that the gap gets pretty
small, say 1/4" , under the side of the pot...

The same thing goes for the space below the pot. Heat Transfer Efficiency
can be raised by tapering the air flow beneath the pot as well. The gap is
usually about 1 and 1/4" directly above the fire tapering down to a
decreasing distance dependent on the size of the pot.

An adjustable skirt can have spacers attached to the inside of the cylinder
so that cooks, for an approximately correct fit, only need to tighten the
skirt as much as possible. The skirt fits under the pot handles.

Here is Ken Goyers explaination of how to calculate cross sectional area:

The way to calculate the height of the gap under the pot in
>order to maintain a constant cross section is as follows:
> First, figure out the area of the combustion chamber. If the
>combustion chamber is five inches in diameter then the area is A=pie r
>squared, or 3.14 x 2.5in. x 2.5in. = 19.6 square inches. 19.6 square
>inches of gasses are proceeding up the rocket elbow and we want to
>maintain the draft and not change it's velocity so we want to maintain
>this cross section under the bottom of the pot as the gasses progress
>outward toward the edge of the pot. At the top edge of the rocket elbow
>the gasses are going to turn and follow the bottom of the pot. The five
>inch diameter has a circumference of C = pie d or 3.14 x 5 inches =
>15.7 inches. If this space were one inch high it would only be 15.7
>square inches. But we need 19.6 square inches. So it needs to be higher
>than one inch or 19.6 / 15.7 = 1.25 inches high over the edge of the
>combustion chamber where the gasses are turning and flowing radially
>under the pot. Now as the gasses go outward the circumference gets
>bigger so the gap must get smaller in order to maintain the same cross
>section. At 7 inches the circumference is C = pie x d or 3.14 x 7 = 22
>inches. So the gap is 19.6 inches divided by 22 inches or .9 inches. At
>9 inches the circumference is C = pie x d or 3.14 x 9 = 28 inches. 19.6
>divided by 28 inches = .7 inches.
> You can figure this height at any diameter under the pot. For
>example if the pot was 20 inches in diameter circumference would be C =
>pie x d or 3.14 x 20 = 63 inches and the gap would be 19.6 divided by 63
>inches or .3 inches. You can figure this as precisely as you wish. You
>can plot it for every inch of the diameter, or even every half inch. But
>with three or four points you can get a good approximation of the cross
>section at various diameters. I hope this helps to explain how to keep
>the cross section equal under the pot so the combustion gasses can
>maintain their velocity and scrub the pot as closely as possible. Best
>regards, Ken
>
Follow the same method to determine the gap between pot and skirt. The
correct gap dramatically improves heat transfer efficiency to the pot which
is the dominant factor influencing fuel efficiency in a wood burning cooking
stove...

Best,

Dean

From tombreed at ATTBI.COM Sun Mar 9 00:40:57 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:17 2004
Subject: Fw: [STOVES] Combustion - Tom Reed
Message-ID: <SAT.8.MAR.2003.224057.0700.TOMBREED@ATTBI.COM>

Dear Shivayam, Crispin and All:

I hope at some time we can make a stove that will test the question of
preheating air without any other changes to settle this matter in a
scientific manner. We are currently making a production run of an optimized
stove and don't want to take time off now.

TOM REED

Dr. Thomas B. Reed
1810 Smith Rd., Golden, CO 80401
tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax
----- Original Message -----
From: "Crispin" <crispin@newdawn.sz>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Wednesday, February 26, 2003 1:37 AM
Subject: Re: [STOVES] Combustion - Tom Reed

> Dear Tom
>
> I like your response - it seems to have validity, and so does my
> interpretation of the innards of the stove, even though is does not
> correspond.
>
> Can we think of an experiment that will show us all the true values of
these
> different analyses?
>
> It would be great if we can think of a way to establish the value of
> preheating air, or otherwise. It appears that the main choice for a stove
> builder is between insulating the chamber and space above it, and letting
> the heat do some work preheating the air on the way to the fire. There is
a
> lot of yatta-yatta about why they both work but if you try to create a
> unified stove theory (UST) there is fundamental conflict between them.
>
> I could build a stove that is capable of both layouts.
>
> We should agree on the parameters and on what and how it is to be tested.
>
> How about it?
>
> Regards
> Crispin, the stove skeptic supporter
>
>
> >Dear Dean, Ron and All:
>
> >I have long been skeptical about the value of preheating
> >combustion air and am glad to have Dean give a few
> >more reasons.
>
> [snip]
> >TOM REED STOVE SKEPTIC
>

From lanny at ROMAN.NET Sun Mar 9 12:01:51 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:17 2004
Subject: Test #3 - Camp Stove #6A
Message-ID: <SUN.9.MAR.2003.090151.0800.LANNY@ROMAN.NET>

Dear Crispin,

LH- 6883 sounds good to me as a standard

>CPP: I would use 6883 as my 'normal' which is 16 >MJ/Kg (I use a higher
>number only for pine). I would calculate that you used >5.632 MJ = 5342
BTU
(>the conversion factor is 948.45)

LH- If we count the pot,
The pot=1.92 lb X 157 deg rise = 301.44 X (specific heat of steel = .11) =
33.16 btu + 2077 for the water = 2110.16/ 5342 energy used = 39.5%.
I noticed that aluminum has twice the sp heat at.22 than steel at .11 and
will hold twice the heat.

> CPP: I get 2077/5342= 38.9% but it is actually a little higher than that
> because there is a bit of heat in the pot (I need the empty pot mass). It
> isn't as much as you might imagine but if you are keeping 4 significant
> digits, you might as well factor it in.

LH- When the water comes to a boil I pull the sticks out and weigh them. I
can't measure the volume lost to boiling.
Fire management effects the efficiency. That is probably the reason for the
difference in efficiency between the test #2 and #3.

Thanks for your response,
Lanny

----- Original Message -----
From: Crispin <crispin@newdawn.sz>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Saturday, March 08, 2003 11:43 AM
Subject: Re: [STOVES] Test #3 - Camp Stove #6A

> Dear Lanny
>
> >Fuel efficiency test- Bring 6 liters of water boil.
> >1- Fuel used = 352 grams of wood.
> >2- Energy used = 5037.5 btu used.
>
> >I am using 6500 btu per pound of air dry wood.
>
> CPP: I would use 6883 as my 'normal' which is 16 MJ/Kg (I use a higher
> number only for pine). I would calculate that you used 5.632 MJ = 5342
BTU
> (the conversion factor is 948.45)
>
> >3- Energy needed for 100% efficiency = 2072.4 btu
>
> CPP: I get 2.2046x6 = 13.228 pounds of water x (212-55) = 2077 BTU plus
the
> heat in the mass of the pot and I count it as 212-55 in your case.
>
> I don't count the stove's mass although a purist might ask you to as you
are
> using it to store heat to recover later with which to cook. Doing that
also
> gives you a theoretical problem which is that if you were asked to cook
> continuously you couldn't recover the heat stored in the stove and it
would
> eventually be lost to the environment. That is why I don't want to use a
> started and stopped stove when rating them because it is a vaguely
> acceptable method of cheating in the cooking of one actual meal in a
single
> pot. Your 'cooking efficiency' would suffer if you had to cook two or
more
> pots in a row.
>
> >4- Efficiency = (41.1%) Energy used 5037.5 btu / energy needed 2072.4 =
> 41.1%
>
> CPP: I get 2077/5342= 38.9% but it is actually a little higher than that
> because there is a bit of heat in the pot (I need the empty pot mass). It
> isn't as much as you might imagine but if you are keeping 4 significant
> digits, you might as well factor it in.
>
> >5- Time to boil 30 min
>
> CPP: This is then an average fuel consumption of 5342 BTU/30 = 178
> BTU/minute or 352/30 = 11.73 gm per minute. I think that it is a useable
> heat on the lower end of what I seek. I like the range of 10-25 gm/minute
> of wood as as a stove's consumption. No matter. What you have is pretty
> good.
>
> Now... this is quite a bit better than your previous effort which you
> reported as using 4.7 litres of water (plus a little salt and oil) and it
> look longer to heat to a boil. I calculated that as follows:
>
> 523 gm (equivalent) of wood = 7937 BTU heating 10.36 pounds of water in 34
> minutes
> or (10.36*(212-55))/7937 = 20.5% efficiency. It was actually higher than
> that for two reasons: you heated the pot as well, and you continued to
boil
> for 3 minutes but you didn't report the loss of water to steam during that
> time (if any). That can be significant.
>
> How much wood was left over? Was it 523 gm (equivalent) that was
consumed?
> I presumed so in that calculation.
>
> So...what was different about this latest test? Was it, for example, a
more
> 'wide open' test? The efficiency is very much higher higher. I am not
> surprised as there was less time to lose heat to the environment. But it
is
> a very significant different. What do you think? Did you realize how
much
> better is it this time round? Whatever you changed it was a 'good thing'.
> Was there less wood loaded in it so it could breathe better?
>
> I think you should try loading it with low loads to see if the efficiency
> goes up. If it does, you should look into the amount of secondary air
> available. When it is loaded with more wood it is probably stifling it in
> some way.
>
> Regards
> Crispin
>

From dstill at EPUD.NET Sun Mar 9 12:36:59 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:17 2004
Subject: Fw: [STOVES] Combustion - Tom Reed
Message-ID: <SUN.9.MAR.2003.093659.0800.DSTILL@EPUD.NET>

I second Tom's desire for a test of preheating secondary air. If no one gets
to it sooner, when Ron Larson, Paul Anderson, Dale Andreatta, myself and
others are all watching we will do a few tests at the ETHOS June Stove
Testing Gathering. This is exactly the reason why we need to all meet at one
place and share together experiments that we jointly conduct.

Best,

Dean
-----Original Message-----
From: Tom Reed <tombreed@attbi.com>
To: STOVES@LISTSERV.REPP.ORG <STOVES@LISTSERV.REPP.ORG>
Date: Sunday, March 09, 2003 5:20 AM
Subject: [STOVES] Fw: [STOVES] Combustion - Tom Reed

>Dear Shivayam, Crispin and All:
>
>I hope at some time we can make a stove that will test the question of
>preheating air without any other changes to settle this matter in a
>scientific manner. We are currently making a production run of an
optimized
>stove and don't want to take time off now.
>
>TOM REED
>
>
>
>Dr. Thomas B. Reed
>1810 Smith Rd., Golden, CO 80401
>tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax

From dstill at EPUD.NET Sun Mar 9 14:17:28 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:17 2004
Subject: Fw: slide show "Making insulative clay combustion chambers"
Message-ID: <SUN.9.MAR.2003.111728.0800.DSTILL@EPUD.NET>

Dear Ron,

The photos of the 6 brick Rocket stove with adjustable skirt can be seen at:
>
>www.ecoharmony.net/hedon/insulation.php
>
>The pictures of the Justa stove are at:
>
>www.ecoharmony.net/hedon/justa.php
>

From dstill at EPUD.NET Mon Mar 10 14:03:35 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <MON.10.MAR.2003.110335.0800.DSTILL@EPUD.NET>

Dear Crispin, Lanny, Ron, etc.,

A while back I floated the idea that our group of stove researchers,
builders and those interested in stoves adapt a common test so that results
are comparable. My general recollection was that the search for consensus
was met with accurate comments that testing is very complicated. I
wholeheartedly agree. But shall we start somewhere...

Should the STOVES and ETHOS group agree to use 6883 as the number of BTU's
in a pound of wood or 16 MJ/Kg (excluding pine), as Crispin suggests?
Agreeing on a number would get us a step closer to accurate communication.

All Best,

Dean

From cree at DOWCO.COM Mon Mar 10 22:23:28 2003
From: cree at DOWCO.COM (JOHN OLSEN)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
In-Reply-To: <003f01c2e737$ca10a060$421e6c0c@default>
Message-ID: <MON.10.MAR.2003.192328.0800.CREE@DOWCO.COM>

Dean,
My presentation contains the following wood BTU per pound list..
Wood Characteristics
Softwoods BTU / lb
Cyprus Western Red 9700
Cyprus yellow 9900
Douglas Fir 9200
Fir Balsam 8616
Fir (unspecified) 8300
Hemlock Western 8500
Larch Western 8530
Pine Jack 8500
Pine Lodgepole 8600
Pine ponderosa 9100
Spruce Sitka 8100
Spruce white 8500
Hardwoods
Alder red 8000
Aspen trembling 8610
Birch white 9340
Cottonwood black 8800
Maple broadleaf 8400
Poplar (unspecified) 8615

I am not sure which wood is 6883?
regards
John Olsen

-----Original Message-----
From: The Stoves Discussion List [mailto:STOVES@LISTSERV.REPP.ORG]On
Behalf Of Dean Still
Sent: Monday, March 10, 2003 11:04 AM
To: STOVES@LISTSERV.REPP.ORG
Subject: Re: [STOVES] standardize testing

Dear Crispin, Lanny, Ron, etc.,

All Best,

Dean

From elk at WANANCHI.COM Mon Mar 10 23:56:46 2003
From: elk at WANANCHI.COM (elk)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <TUE.11.MAR.2003.075646.0300.ELK@WANANCHI.COM>

I agree on the need for test standardisation- something we list members have
made occasional efforts toward.

Remember the F.o.M.- Figure of Merit? We use our own version for assessing
various charcoals, but it's only applicable to one charcoal stove type.

We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a somewhat
demographically restricted unit of measure I believe......

And 22 MJ/Kg for pure wood charcoal? Obviously any adulteration from (for
example) the inclusion of inert binders or fossil coal in a briquette would
necessitate a statement of specific fuel energy value.

Should an uncovered pot be used if the test relies on measuring evaporative
(boiling) water loss? This would cause some problems for cookers such as the
Karve's- an enclosed stack of pots. The question here is; does a covered
boiling pot lose less water than an open one? A covered pot comes to a boil
quicker and maintains the boil longer for a given energy input.

Regards to all;

elk

--------------------------
Elsen L. Karstad
elk@wananchi.com
www.chardust.com
Nairobi Kenya

----- Original Message -----
From: "Dean Still" <dstill@epud.net>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Monday, March 10, 2003 10:03 PM
Subject: Re: [STOVES] standardize testing

> Dear Crispin, Lanny, Ron, etc.,
>
> A while back I floated the idea that our group of stove researchers,
> builders and those interested in stoves adapt a common test so that
results
> are comparable. My general recollection was that the search for consensus
> was met with accurate comments that testing is very complicated. I
> wholeheartedly agree. But shall we start somewhere...
>
> Should the STOVES and ETHOS group agree to use 6883 as the number of BTU's
> in a pound of wood or 16 MJ/Kg (excluding pine), as Crispin suggests?
> Agreeing on a number would get us a step closer to accurate communication.
>
> All Best,
>
> Dean
>

From koopmans at LOXINFO.CO.TH Tue Mar 11 02:10:39 2003
From: koopmans at LOXINFO.CO.TH (Auke Koopmans)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <TUE.11.MAR.2003.141039.0700.KOOPMANS@LOXINFO.CO.TH>

Dear All,

Lots has been written about stove testing and whole international meetings
were devoted to this issue in the eightees. If someone would be interested I
probably can find somewhere in my documents the (at that time) agreed upon
testing method. However later other methods were proposed, developed and/or
used.

India and China have their own testing metods which can be found on our
website http://www.rwedp.org . Look for Publications (at the left) and
choose then Utilization (Stoves, Industries) where you will find:
FD 40 Chinese Fuel Saving Stoves Page 51-56 Testing methods used in China as
well as
FD 41 Indian Improved Cookstoves Page 96-104 Testing method used in India.

Best regards,

Auke Koopmans

----- Original Message -----
From: "elk" <elk@WANANCHI.COM>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Tuesday, March 11, 2003 11:56 AM
Subject: Re: [STOVES] standardize testing

> I agree on the need for test standardisation- something we list members
have
> made occasional efforts toward.
>
> Remember the F.o.M.- Figure of Merit? We use our own version for assessing
> various charcoals, but it's only applicable to one charcoal stove type.
>
> We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a
somewhat
> demographically restricted unit of measure I believe......
>
> And 22 MJ/Kg for pure wood charcoal? Obviously any adulteration from (for
> example) the inclusion of inert binders or fossil coal in a briquette
would
> necessitate a statement of specific fuel energy value.
>
> Should an uncovered pot be used if the test relies on measuring
evaporative
> (boiling) water loss? This would cause some problems for cookers such as
the
> Karve's- an enclosed stack of pots. The question here is; does a covered
> boiling pot lose less water than an open one? A covered pot comes to a
boil
> quicker and maintains the boil longer for a given energy input.
>
> Regards to all;
>
> elk
>
>
> --------------------------
> Elsen L. Karstad
> elk@wananchi.com
> www.chardust.com
> Nairobi Kenya
>
>
>
> ----- Original Message -----
> From: "Dean Still" <dstill@epud.net>
> To: <STOVES@LISTSERV.REPP.ORG>
> Sent: Monday, March 10, 2003 10:03 PM
> Subject: Re: [STOVES] standardize testing
>
>
> > Dear Crispin, Lanny, Ron, etc.,
> >
> > A while back I floated the idea that our group of stove researchers,
> > builders and those interested in stoves adapt a common test so that
> results
> > are comparable. My general recollection was that the search for
consensus
> > was met with accurate comments that testing is very complicated. I
> > wholeheartedly agree. But shall we start somewhere...
> >
> > Should the STOVES and ETHOS group agree to use 6883 as the number of
BTU's
> > in a pound of wood or 16 MJ/Kg (excluding pine), as Crispin suggests?
> > Agreeing on a number would get us a step closer to accurate
communication.
> >
> > All Best,
> >
> > Dean
> >
>

From elk at WANANCHI.COM Tue Mar 11 03:03:20 2003
From: elk at WANANCHI.COM (elk)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <TUE.11.MAR.2003.110320.0300.ELK@WANANCHI.COM>

Auke;

Downloading these docs is difficult for me (and others I'm sure) due to file
size- could you cut & paste the relevant section(s) on test protocol for us?

Thanks!

elk

--------------------------
Elsen L. Karstad
elk@wananchi.com
www.chardust.com
Nairobi Kenya

----- Original Message -----
From: "Auke Koopmans" <koopmans@LOXINFO.CO.TH>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Tuesday, March 11, 2003 10:10 AM
Subject: Re: [STOVES] standardize testing

> Dear All,
>
> Lots has been written about stove testing and whole international meetings
> were devoted to this issue in the eightees. If someone would be interested
I
> probably can find somewhere in my documents the (at that time) agreed upon
> testing method. However later other methods were proposed, developed
and/or
> used.
>
> India and China have their own testing metods which can be found on our
> website http://www.rwedp.org . Look for Publications (at the left) and
> choose then Utilization (Stoves, Industries) where you will find:
> FD 40 Chinese Fuel Saving Stoves Page 51-56 Testing methods used in China
as
> well as
> FD 41 Indian Improved Cookstoves Page 96-104 Testing method used in India.
>
> Best regards,
>
> Auke Koopmans
>
> ----- Original Message -----
> From: "elk" <elk@WANANCHI.COM>
> To: <STOVES@LISTSERV.REPP.ORG>
> Sent: Tuesday, March 11, 2003 11:56 AM
> Subject: Re: [STOVES] standardize testing
>
>
> > I agree on the need for test standardisation- something we list members
> have
> > made occasional efforts toward.
> >
> > Remember the F.o.M.- Figure of Merit? We use our own version for
assessing
> > various charcoals, but it's only applicable to one charcoal stove type.
> >
> > We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a
> somewhat
> > demographically restricted unit of measure I believe......
> >
> > And 22 MJ/Kg for pure wood charcoal? Obviously any adulteration from
(for
> > example) the inclusion of inert binders or fossil coal in a briquette
> would
> > necessitate a statement of specific fuel energy value.
> >
> > Should an uncovered pot be used if the test relies on measuring
> evaporative
> > (boiling) water loss? This would cause some problems for cookers such as
> the
> > Karve's- an enclosed stack of pots. The question here is; does a covered
> > boiling pot lose less water than an open one? A covered pot comes to a
> boil
> > quicker and maintains the boil longer for a given energy input.
> >
> > Regards to all;
> >
> > elk
> >
> >
> > --------------------------
> > Elsen L. Karstad
> > elk@wananchi.com
> > www.chardust.com
> > Nairobi Kenya
> >
> >
> >
> > ----- Original Message -----
> > From: "Dean Still" <dstill@epud.net>
> > To: <STOVES@LISTSERV.REPP.ORG>
> > Sent: Monday, March 10, 2003 10:03 PM
> > Subject: Re: [STOVES] standardize testing
> >
> >
> > > Dear Crispin, Lanny, Ron, etc.,
> > >
> > > A while back I floated the idea that our group of stove researchers,
> > > builders and those interested in stoves adapt a common test so that
> > results
> > > are comparable. My general recollection was that the search for
> consensus
> > > was met with accurate comments that testing is very complicated. I
> > > wholeheartedly agree. But shall we start somewhere...
> > >
> > > Should the STOVES and ETHOS group agree to use 6883 as the number of
> BTU's
> > > in a pound of wood or 16 MJ/Kg (excluding pine), as Crispin suggests?
> > > Agreeing on a number would get us a step closer to accurate
> communication.
> > >
> > > All Best,
> > >
> > > Dean
> > >
> >
>
>

From koopmans at LOXINFO.CO.TH Tue Mar 11 05:01:04 2003
From: koopmans at LOXINFO.CO.TH (Auke Koopmans)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <TUE.11.MAR.2003.170104.0700.KOOPMANS@LOXINFO.CO.TH>

Elk,

That is difficult as these are PDF files (each about 1 Mb in size). Copying
the relevant part and pasting them in a doc or txt files results in that all
equations are completely mixed up and it will take me a long time (and time
is in short supply) to get them back into a readable form.

Regards,

Auke

----- Original Message -----
From: "elk" <elk@WANANCHI.COM>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Tuesday, March 11, 2003 3:03 PM
Subject: Re: [STOVES] standardize testing

> Auke;
>
> Downloading these docs is difficult for me (and others I'm sure) due to
file
> size- could you cut & paste the relevant section(s) on test protocol for
us?
>
> Thanks!
>
> elk
>
>
> --------------------------
> Elsen L. Karstad
> elk@wananchi.com
> www.chardust.com
> Nairobi Kenya
>
>
>
> ----- Original Message -----
> From: "Auke Koopmans" <koopmans@LOXINFO.CO.TH>
> To: <STOVES@LISTSERV.REPP.ORG>
> Sent: Tuesday, March 11, 2003 10:10 AM
> Subject: Re: [STOVES] standardize testing
>
>
> > Dear All,
> >
> > Lots has been written about stove testing and whole international
meetings
> > were devoted to this issue in the eightees. If someone would be
interested
> I
> > probably can find somewhere in my documents the (at that time) agreed
upon
> > testing method. However later other methods were proposed, developed
> and/or
> > used.
> >
> > India and China have their own testing metods which can be found on our
> > website http://www.rwedp.org . Look for Publications (at the left) and
> > choose then Utilization (Stoves, Industries) where you will find:
> > FD 40 Chinese Fuel Saving Stoves Page 51-56 Testing methods used in
China
> as
> > well as
> > FD 41 Indian Improved Cookstoves Page 96-104 Testing method used in
India.
> >
> > Best regards,
> >
> > Auke Koopmans
> >
> > ----- Original Message -----
> > From: "elk" <elk@WANANCHI.COM>
> > To: <STOVES@LISTSERV.REPP.ORG>
> > Sent: Tuesday, March 11, 2003 11:56 AM
> > Subject: Re: [STOVES] standardize testing
> >
> >
> > > I agree on the need for test standardisation- something we list
members
> > have
> > > made occasional efforts toward.
> > >
> > > Remember the F.o.M.- Figure of Merit? We use our own version for
> assessing
> > > various charcoals, but it's only applicable to one charcoal stove
type.
> > >
> > > We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a
> > somewhat
> > > demographically restricted unit of measure I believe......
> > >
> > > And 22 MJ/Kg for pure wood charcoal? Obviously any adulteration from
> (for
> > > example) the inclusion of inert binders or fossil coal in a briquette
> > would
> > > necessitate a statement of specific fuel energy value.
> > >
> > > Should an uncovered pot be used if the test relies on measuring
> > evaporative
> > > (boiling) water loss? This would cause some problems for cookers such
as
> > the
> > > Karve's- an enclosed stack of pots. The question here is; does a
covered
> > > boiling pot lose less water than an open one? A covered pot comes to a
> > boil
> > > quicker and maintains the boil longer for a given energy input.
> > >
> > > Regards to all;
> > >
> > > elk
> > >
> > >
> > > --------------------------
> > > Elsen L. Karstad
> > > elk@wananchi.com
> > > www.chardust.com
> > > Nairobi Kenya
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Dean Still" <dstill@epud.net>
> > > To: <STOVES@LISTSERV.REPP.ORG>
> > > Sent: Monday, March 10, 2003 10:03 PM
> > > Subject: Re: [STOVES] standardize testing
> > >
> > >
> > > > Dear Crispin, Lanny, Ron, etc.,
> > > >
> > > > A while back I floated the idea that our group of stove researchers,
> > > > builders and those interested in stoves adapt a common test so that
> > > results
> > > > are comparable. My general recollection was that the search for
> > consensus
> > > > was met with accurate comments that testing is very complicated. I
> > > > wholeheartedly agree. But shall we start somewhere...
> > > >
> > > > Should the STOVES and ETHOS group agree to use 6883 as the number of
> > BTU's
> > > > in a pound of wood or 16 MJ/Kg (excluding pine), as Crispin
suggests?
> > > > Agreeing on a number would get us a step closer to accurate
> > communication.
> > > >
> > > > All Best,
> > > >
> > > > Dean
> > > >
> > >
> >
> >
>

From Carefreeland at AOL.COM Tue Mar 11 05:06:05 2003
From: Carefreeland at AOL.COM (Carefreeland@AOL.COM)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
Message-ID: <TUE.11.MAR.2003.050605.EST.>

In a message dated 3/10/03 10:26:31 PM Eastern Standard Time, cree@DOWCO.COM
writes:

DD Dan Dimiduk comments
>
> Dean,
> My presentation contains the following wood BTU per pound list..
> Wood Characteristics
> Softwoods BTU / lb
> Cyprus Western Red 9700
> Cyprus yellow 9900
> Douglas Fir 9200
> Fir Balsam 8616
> Fir (unspecified) 8300
> Hemlock Western 8500
> Larch Western 8530
> Pine Jack 8500
> Pine Lodgepole 8600
> Pine ponderosa 9100
> Spruce Sitka 8100
> Spruce white 8500
> Hardwoods
> Alder red 8000
> Aspen trembling 8610
> Birch white 9340
> Cottonwood black 8800
> Maple broadleaf 8400
> Poplar (unspecified) 8615
>
> I am not sure which wood is 6883?
> regards
> John Olsen
>
>
DD Other than the Maple, I'm not sure if any of these would classify as
hardwoods here in Ohio. Even Red and Silver Maple are classified has trash
softwoods around here and the tree services pay tipping fees to dump them and
any of these listed woods.

DD We heat our homes and cook with: Oak's, Beach, Hickory's, Hard maple's,
Locust's, Walnut, Ash, Black Cherry, Apple, Hedge(Osage orange), Ironwood
(American hophornbeam) Redbud, Elm, Dogwood and others.

DD These woods all fall between 7143 and 6765 btu per pound "air dry". The
key words here being "air dry". I am sure that any wood "Western USA bone
dry" has far more btu's per pound than "Eastern USA air dry" wood. The
day/night average realitive humidity is seldom under 50%. Can anybody give a
figure for the BTU difference between 12-15% moisture by weight, and 2%
moisture by weight? Given the energy and efficiancy loss of boiling trapped
water, I'm sure it is MUCH greater than a 10% difference.
That is where your confusion takes place.

Daniel Dimiduk

From yark at U.WASHINGTON.EDU Tue Mar 11 05:29:02 2003
From: yark at U.WASHINGTON.EDU (Tami Bond)
Date: Tue Aug 10 18:30:17 2004
Subject: standardize testing
In-Reply-To: <01ca01c2e7b5$22271a40$5f8992cb@aukeufr0ppg2sw>
Message-ID: <TUE.11.MAR.2003.022902.0800.YARK@U.WASHINGTON.EDU>

Well, heck, *I* have nothing else to do, or at least I needed a break. I
chopped out the relevant pages and put them on my stoves page so people
can download them. I don't have time to make them into text so they are
still 50-kb pdf each, but it's better than 1 meg. Hope this is not
illegal.

http://faculty.washington.edu/~yark/stoves.html, just right click on the
links next to 'Testing Protocols' to download.

And if we must standardize, please remember that not everyone has
calculators handy, so how about 7000 instead of 6883?

Tami

> Elk,
>
> That is difficult as these are PDF files (each about 1 Mb in size). Copying
> the relevant part and pasting them in a doc or txt files results in that all
> equations are completely mixed up and it will take me a long time (and time
> is in short supply) to get them back into a readable form.
>

From Visser at BTGWORLD.COM Tue Mar 11 05:42:47 2003
From: Visser at BTGWORLD.COM (Piet Visser)
Date: Tue Aug 10 18:30:17 2004
Subject: Stove testing
Message-ID: <TUE.11.MAR.2003.114247.0100.VISSER@BTGWORLD.COM>

Dear stovers,

I am surprised by the discussion about testing procedures. As Auke has
pointed out, "lots has been written about stove testing and whole
international meetings were devoted to this issue in the eightees".
The result has been a document called:

"Testing the Efficiency of Woodburning Cookstoves: International
Standards", (ISBN 0-86619-229-8), Volunteers In Technical Assistance, 1815
N.Lynn Street, Suite 200, Arlington, Virginia 22209, USA.

These standards were a merger of the two main approaches to stove testing
in those days, the "field oriented approach"and the "lab oriented
approach". According to the field oriented approach test results should be
expressed as "fuel consumption figures", whereas the lab oriented approach
expressed the results in "power and efficiency". The dispute was academic,
because by simple calculation the one result could be easily converted to
the other.

At the "Woodburning Stove Group" of Eindhoven University of Technology, one
of the leading cookstove research centers in the eighties, we have
intensively participated in the discussion and finally developped a testing
procedure, based on the VITA standard, that I have been using since and
that has proven to give good, reliable and reproducible results. It also
offers the possibility to compare test results from different places and
different fuels.

Basis of the testing procedure are the waterboiling tests with which the
high power and the low power of a stove are determined, with their
respective efficiencies.
This data then is used to calculate fuel consumption for the preparation of
a "standard" meal, according to the method proposed by K.K.Prasad
(K.Krishna Prasad: "Woodburning Stoves: their technology, economics and
deployment", march 1983, ILO, Geneva).

Basicly, in this calculation, the assumption is that for cooking first a
high power phase is needed to bring the content of the pan to the boil,
then a low power phase to simmer the food to make it edible. From the
quantities of food ingredients and their respective specific heats, the
heat capacity for the pan can be determined. Then, using high power and
efficiency numbers from the waterboiling tests, fuel consumption to bring
the pan to the boil can be calculated. Next, from the time necessary to
simmer (a food specific quantity) and the low power, the fuel consumption
for the low power phase can be calculated and hence the total fuel
consumtion for the preparation os the standard meal. In practise the
calculation procedure can be more detailed (correction for evaporated water
during simmering, extended period of high power, etc) and expanded (deep
frying etc.).

In a number of projects I have done these calculations and compared the
results with the results of controlled cooking tests. The calculations
consistently give lower consumption figures than the controlled cooking
tests, but the correlation is good. The calculated fuel consumption
provides an easy and quick method to compare stoves and to estimate their
fuel consumption.

People who are interested in the testing procedure I can provide with a
procedure description and a basic spreadsheet.

Finally. I propose a ban on the BTU (as well as the pound, inch etc.) as a
unit on this forum. If I am correct it was in the fifties that
internationally has been agreed to convert to the metric system. So as far
as I am concerned there is no reason for existence anymore for an archaic
unit as the BTU/pound, except maybe in history class.

Best regards,

Piet Visser
_____________________________________________________________

Piet Visser
BTG biomass technology group B.V.
c/o University of Twente
Postal address : P.O. Box 217, 7500 AE Enschede, The Netherlands
Physical address : Drienerlolaan 5, 7522 NB Enschede, The Netherlands

Phone : +31 53 489 2897
Direct : +31 53 489 2889
Fax : +31 53 489 3116
E-mail : Office@btgworld.com
Direct : visser@btgworld.com

==> Visit our website at <http://www.btgworld.com> <==
==> Visit our website at <http://www.ecogas.nl> <==
==> Visit the stove website at <http://www.cookstove.net> <==
_____________________________________________________________

From tombreed at ATTBI.COM Tue Mar 11 00:27:17 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:17 2004
Subject: Finally a stove testing procedure...
Message-ID: <MON.10.MAR.2003.222717.0700.TOMBREED@ATTBI.COM>

Dear Piet Visser and all:

I am in complete agreement with Piet's discussion below. His
recommendations are close to what we have done at the BEF and CPC for 10
years.

Also thanks for the discussion of ditching the Btu - an embarrassment to me
and the U.S. (Our 18 year old grandson is visiting from Massachusetts and
we ONLY talk Joules and metric!) The effort of learning metric pays off
100fold when making calculations.

Piet, please send me your spreadsheet. Thanks for the level advice.

TOM REED BEF STOVEWORKS

Dr. Thomas B. Reed
1810 Smith Rd., Golden, CO 80401
tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax
----- Original Message -----
From: "Piet Visser" <Visser@BTGWORLD.COM>
To: < >
Sent: Tuesday, March 11, 2003 3:42 AM
Subject: [STOVES] Stove testing

> Dear stovers,
>
> I am surprised by the discussion about testing procedures. As Auke has
> pointed out, "lots has been written about stove testing and whole
> international meetings were devoted to this issue in the eightees".
> The result has been a document called:
>
> "Testing the Efficiency of Woodburning Cookstoves: International
> Standards", (ISBN 0-86619-229-8), Volunteers In Technical Assistance, 1815
> N.Lynn Street, Suite 200, Arlington, Virginia 22209, USA.
>
> These standards were a merger of the two main approaches to stove testing
> in those days, the "field oriented approach"and the "lab oriented
> approach". According to the field oriented approach test results should be
> expressed as "fuel consumption figures", whereas the lab oriented approach
> expressed the results in "power and efficiency". The dispute was academic,
> because by simple calculation the one result could be easily converted to
> the other.
>
> At the "Woodburning Stove Group" of Eindhoven University of Technology,
one
> of the leading cookstove research centers in the eighties, we have
> intensively participated in the discussion and finally developped a
testing
> procedure, based on the VITA standard, that I have been using since and
> that has proven to give good, reliable and reproducible results. It also
> offers the possibility to compare test results from different places and
> different fuels.
>
> Basis of the testing procedure are the waterboiling tests with which the
> high power and the low power of a stove are determined, with their
> respective efficiencies.
> This data then is used to calculate fuel consumption for the preparation
of
> a "standard" meal, according to the method proposed by K.K.Prasad
> (K.Krishna Prasad: "Woodburning Stoves: their technology, economics and
> deployment", march 1983, ILO, Geneva).
>
> Basicly, in this calculation, the assumption is that for cooking first a
> high power phase is needed to bring the content of the pan to the boil,
> then a low power phase to simmer the food to make it edible. From the
> quantities of food ingredients and their respective specific heats, the
> heat capacity for the pan can be determined. Then, using high power and
> efficiency numbers from the waterboiling tests, fuel consumption to bring
> the pan to the boil can be calculated. Next, from the time necessary to
> simmer (a food specific quantity) and the low power, the fuel consumption
> for the low power phase can be calculated and hence the total fuel
> consumtion for the preparation os the standard meal. In practise the
> calculation procedure can be more detailed (correction for evaporated
water
> during simmering, extended period of high power, etc) and expanded (deep
> frying etc.).
>
> In a number of projects I have done these calculations and compared the
> results with the results of controlled cooking tests. The calculations
> consistently give lower consumption figures than the controlled cooking
> tests, but the correlation is good. The calculated fuel consumption
> provides an easy and quick method to compare stoves and to estimate their
> fuel consumption.
>
> People who are interested in the testing procedure I can provide with a
> procedure description and a basic spreadsheet.
>
> Finally. I propose a ban on the BTU (as well as the pound, inch etc.) as a
> unit on this forum. If I am correct it was in the fifties that
> internationally has been agreed to convert to the metric system. So as far
> as I am concerned there is no reason for existence anymore for an archaic
> unit as the BTU/pound, except maybe in history class.
>
> Best regards,
>
> Piet Visser
> _____________________________________________________________
>
> Piet Visser
> BTG biomass technology group B.V.
> c/o University of Twente
> Postal address : P.O. Box 217, 7500 AE Enschede, The Netherlands
> Physical address : Drienerlolaan 5, 7522 NB Enschede, The Netherlands
>
> Phone : +31 53 489 2897
> Direct : +31 53 489 2889
> Fax : +31 53 489 3116
> E-mail : Office@btgworld.com
> Direct : visser@btgworld.com
>
> ==> Visit our website at <http://www.btgworld.com> <==
> ==> Visit our website at <http://www.ecogas.nl> <==
> ==> Visit the stove website at <http://www.cookstove.net> <==
> _____________________________________________________________
>

From tombreed at ATTBI.COM Tue Mar 11 02:35:19 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:17 2004
Subject: Biomass Energy Content Diatribe
Message-ID: <TUE.11.MAR.2003.003519.0700.TOMBREED@ATTBI.COM>

Dear Dean, Ethos,Stoves and Gasification

Having used various figures for the energy content of wood, written books
about it and collected large quantities of data, I get impatient with the
occasional obsession for finding an exact reference to a particular species,
(as if all samples of a named species were the same.)

Mother Nature has made understanding the energy content of most biomass
simple, once you understand the principles.

1) Most biomass consists of ~ 50% cellulose, 25% hemicellulose and 25%
lignin - plus WATER and ASH.

2) Go to my collection of both measured and calculated energy contents at

http://www.woodgas.com/proximat.htm

and run your eye down the HHV Measured and HHV Calculated column. For the
15 wood species the energy content only varies from 19-21 kJ/g (MJ/kg).
Then note that most of the other biomass species are also in this range.

3) So why do you hear lesser figures sometimes? Because heating value
figures are often not reported on a DRY ASH-FREE basis. The National Bureau
of Standards wrote a book , E. Domalski et al, "Thermodynamic Data for
Biomass Materials and Waste Components", ASME, 1987. A casual reading would
have convinced you that biomass energies were all over the map. In Appendix
A, I recalculated some of the data on a dry ash-free basis and verified that
most biomass is 18-20 kJ/g. Since then I can come within 10% of a good
heating value estimate provided I know water and ash.

It is not surprising that if you have 10,20, or 30% moisture that you will
have 10, 20 or 30% less energy! Also some biomass species have 2-20% ash.
Again, reduced energy.

Having stated the general rule, it is important to recognize the exceptions:

4) Bark, Charcoal, pyrolysis oil, oils and fats, nuts, ... Look the list
over and get a feel. Then measure water content and ash content on your
particular fuel, add them back in and you will have an accurate estimate.
(Or send it to a lab for analysis, typically <$150). Look down the column
and you'll find some other exceptions.

And let's not hear any more about Btus in this forum.

I hope this helps clarify the biomass energy issues.

Yours truly, TOM REED BEF PRESS

Dr. Thomas B. Reed
1810 Smith Rd., Golden, CO 80401
tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax
----- Original Message -----
From: "Dean Still" <dstill@epud.net>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Monday, March 10, 2003 12:03 PM
Subject: Re: [STOVES] standardize testing

From robert.wyatt at MAIL.UTEXAS.EDU Tue Mar 11 11:53:08 2003
From: robert.wyatt at MAIL.UTEXAS.EDU (Robert T. Wyatt)
Date: Tue Aug 10 18:30:17 2004
Subject: metric [was: Finally a stove testing procedure...]
In-Reply-To: <004001c2e78e$e1ddffb0$c281fd0c@TOMBREED>
Message-ID: <TUE.11.MAR.2003.105308.0600.ROBERT.WYATT@MAIL.UTEXAS.EDU>

Before I go and find a convenient chart that gives some standard Btu
-> metric conversions, does any one know of one that already exists?
Or some benchmark values that they would like to see converted? I'll
post what I find to the list.

>Also thanks for the discussion of ditching the Btu - an embarrassment to me
>and the U.S. (Our 18 year old grandson is visiting from Massachusetts and
>we ONLY talk Joules and metric!) The effort of learning metric pays off
>100fold when making calculations.

From hseaver at CYBERSHAMANIX.COM Tue Mar 11 13:07:01 2003
From: hseaver at CYBERSHAMANIX.COM (Harmon Seaver)
Date: Tue Aug 10 18:30:17 2004
Subject: metric [was: Finally a stove testing procedure...]
In-Reply-To: <p05200f00ba93c4178c26@[128.83.86.30]>
Message-ID: <TUE.11.MAR.2003.120701.0600.HSEAVER@CYBERSHAMANIX.COM>

The best one I know of is Units (http://sourceforge.net/projects/units/),
unfortunately for most here it only runs on Unix. It seems to come bundled with
most linux distrobutions, and does pretty much any conversion you (or at least
I) can imagine.

On Tue, Mar 11, 2003 at 10:53:08AM -0600, Robert T. Wyatt wrote:
> Before I go and find a convenient chart that gives some standard Btu
> -> metric conversions, does any one know of one that already exists?
> Or some benchmark values that they would like to see converted? I'll
> post what I find to the list.
>
> >Also thanks for the discussion of ditching the Btu - an embarrassment to me
> >and the U.S. (Our 18 year old grandson is visiting from Massachusetts and
> >we ONLY talk Joules and metric!) The effort of learning metric pays off
> >100fold when making calculations.

--
Harmon Seaver
CyberShamanix
http://www.cybershamanix.com

From dandreatta at FTICONSULTING.COM Tue Mar 11 13:09:42 2003
From: dandreatta at FTICONSULTING.COM (Andreatta, Dale A.)
Date: Tue Aug 10 18:30:17 2004
Subject: "fans" for stoves
Message-ID: <TUE.11.MAR.2003.130942.0500.DANDREATTA@FTICONSULTING.COM>

A number of people seem to think that the key to designing a good stove is
to have a fan driving the air flow. There's a lot of merit to this idea, I
think, but the big question is how to devise a simple fan. How about this?

Instead of a traditional fan, use a steam driven injector pump. An injector
pump is a device with no moving parts which uses a small jet of high
velocity gas to push another gas at lower speed through a larger tube. You
could rig up a small boiler made of some metal tubing to generate low
pressure steam, perhaps under a pressure of 18 inches of water (4600
Pascals) or so. This is still enough to produce a small steam jet at about
100 meters per second. When blown through a larger tube of the appropriate
size and shape, this steam jet can produce an air velocity of about 7 meters
per second and sufficient airflow to run a stove. This is about what you'd
get with a small fan, and a lot more velocity than you'll ever get with
natural convection. High velocity can be used to create turbulence. My
calculations show that you'd use about 8% of the energy in the wood to
produce the steam if the system were set up correctly.

There are a number of places where you could put the jet. You could have
the injector pump blowing air into the stove at the bottom and get lots of
turbulence at the fire. Or, you could use the jet to blow the combustion
products directly at the bottom of the pot, producing a lot of turbulence at
the pot, increasing heat transfer there while at the same time sucking air
into the bottom of the stove, though probably not with the same level of
turbulence as you would if you'd put the steam injector at the bottom of the
stove. As a 3rd alternative you might set up a recirculating flow pattern,
pulling pollutant-laden gases from just below the pot and pulling them down
and under the fire, where they will pass through the fire again (highly
preheated) and burn again. This may or may not be good, but might be worth
trying.

I've done some theoretical analysis of this idea, though I'm sure it would
take a lot of tinkering to get it to work right. Tinkering is something for
which I don't have a lot of time, but if someone wanted to take this idea
and run with it, I'd be glad to pass along what I've learned from
theoretical study. Mostly, I generated equations to analyze the steam
injector, since I couldn't find them in any book, and I've also done some
basic calculations about what the boiler might be like.

Dale Andreatta
March 11, 2003

From mheat at MHA-NET.ORG Tue Mar 11 16:35:55 2003
From: mheat at MHA-NET.ORG (Norbert Senf)
Date: Tue Aug 10 18:30:17 2004
Subject: metric [was: Finally a stove testing procedure...]
In-Reply-To: <p05200f00ba93c4178c26@[128.83.86.30]>
Message-ID: <TUE.11.MAR.2003.163555.0500.MHEAT@MHANET.ORG>

At 10:53 AM 2003-03-11 -0600, Robert T. Wyatt wrote:
>Before I go and find a convenient chart that gives some standard Btu
>-> metric conversions, does any one know of one that already exists?
>Or some benchmark values that they would like to see converted? I'll
>post what I find to the list.

I've got a converter for energy, pressure, flow, etc., that I made up in
Excel 97 for Windows:

You can download it at:

http://mha-net.org/msb/docs/conversions.xls

Best ...... Norbert

----------------------------------------
Norbert Senf---------- mheat@mha-net.org-nospam
Masonry Stove Builders (remove -nospam)
RR 5, Shawville------- www.heatkit.com
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From dstill at EPUD.NET Wed Mar 12 01:56:25 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:17 2004
Subject: Stove testing
Message-ID: <TUE.11.MAR.2003.225625.0800.DSTILL@EPUD.NET>

Dear Piet,

Thanks so much for your insightful (as always) summary of stove testing. I
would like to "test the waters" to see if we, STOVES, ETHOS members can come
to an agreement to use a standard test. People are using very different
tests which makes comparison of results difficult. Please send me the
procedure description and basic spreadsheet that you described. Is there any
way to post it to all STOVES, ETHOS members? Perhaps STOVES, ETHOS could
consider this procedure and see if a consensus occurs?

I'd like to use an accepted international method when we test stoves here in
June.

AND LASTLY...OK!! I acquiesce and do hereby give up the BTU, inches, pounds,
etc. only asking for leniency when, confused, I muddle up something
important. I agree to do this, leaving behind such a nice warm familiar
world, only because my respect for you, my dear associates, overcomes the
most basic component of my character: laziness.

All Best,

Dean

From tombreed at ATTBI.COM Wed Mar 12 01:56:31 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:18 2004
Subject: Stove testing
Message-ID: <TUE.11.MAR.2003.235631.0700.TOMBREED@ATTBI.COM>

Dear Dean and All:

I loved Dean's agreement to give up BTUs etc.

I remember at the beginning of the energy crises in 1974 that, as a
practicing chemist, I was 90% metric in all I wrote and thought, but used
English for ordinary units (miles, feet, ...). There was a proclamation by
the Department of Energy equivalent that we would all use metric, and I
looked forward to my final purification.

Instead there was zero compliance and I was forced back into English units I
had never used before. I even had to teach in them. So, now I'm reasonably
bi-lingual.

However, I recognize that

1) most of the world has converted and the US is being left farther and
farther behind in technology...
2) lots of engineering confusion is caused by bad translation (shuttle
accident)
3) metric is basically simpler

so I applaud Dean's decision and I hope we can all support it here in this
international community.

Onward and upward and metric, TOM REED BEF
Dr. Thomas B. Reed
1810 Smith Rd., Golden, CO 80401
tombreed@attbi.com; 303 278 0558 Phone; 303 265 9184 Fax
----- Original Message -----
From: "Dean Still" <dstill@epud.net>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Tuesday, March 11, 2003 11:56 PM
Subject: Re: [STOVES] Stove testing

> Dear Piet,
>
> Thanks so much for your insightful (as always) summary of stove testing. I
> would like to "test the waters" to see if we, STOVES, ETHOS members can
come
> to an agreement to use a standard test. People are using very different
> tests which makes comparison of results difficult. Please send me the
> procedure description and basic spreadsheet that you described. Is there
any
> way to post it to all STOVES, ETHOS members? Perhaps STOVES, ETHOS could
> consider this procedure and see if a consensus occurs?
>
> I'd like to use an accepted international method when we test stoves here
in
> June.
>
> AND LASTLY...OK!! I acquiesce and do hereby give up the BTU, inches,
pounds,
> etc. only asking for leniency when, confused, I muddle up something
> important. I agree to do this, leaving behind such a nice warm familiar
> world, only because my respect for you, my dear associates, overcomes the
> most basic component of my character: laziness.
>
> All Best,
>
> Dean
>

From pverhaart at OPTUSNET.COM.AU Thu Mar 13 02:14:01 2003
From: pverhaart at OPTUSNET.COM.AU (Peter Verhaart)
Date: Tue Aug 10 18:30:18 2004
Subject: Fwd: Re: [STOVES] standardize testing
Message-ID: <THU.13.MAR.2003.171401.1000.PVERHAART@OPTUSNET.COM.AU>

>Date: Thu, 13 Mar 2003 17:13:03 +1000
>To: elk <elk@WANANCHI.COM>
>From: Peter Verhaart <pverhaart@optusnet.com.au>
>Subject: Re: [STOVES] standardize testing
>
>At 07:56 11/03/03 +0300, you wrote:
>
>
>>We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a somewhat
>>demographically restricted unit of measure I believe......
>
>Hear hear!
>
>
>>And 22 MJ/Kg for pure wood charcoal?
>
>Isn't carbon around 30 MJ/kg? With wood generally containing 1 % ash and
>yielding 25 % of charcoal, one could expect 4 % ash in charcoal. If the
>remainder is carbon we would get around 28 MJ/kg.
>
>
>>Should an uncovered pot be used if the test relies on measuring evaporative
>>(boiling) water loss? This would cause some problems for cookers such as the
>>Karve's- an enclosed stack of pots. The question here is; does a covered
>>boiling pot lose less water than an open one?
>
>Yes, there is a water loss through diffusion of vapour statring far below
>boiling point. It still needs all those MJ/kg heat input but at a lower
>temperature where we can expect a higher heat transfer. Most if not all
>cooking processes work at boiling point so a covered pot would give a more
>true figure.
>
>Piet

From pverhaart at OPTUSNET.COM.AU Thu Mar 13 02:21:16 2003
From: pverhaart at OPTUSNET.COM.AU (Peter Verhaart)
Date: Tue Aug 10 18:30:18 2004
Subject: Stove testing
In-Reply-To: <4.2.0.58.20030311094726.00a21f00@192.168.10.1>
Message-ID: <THU.13.MAR.2003.172116.1000.PVERHAART@OPTUSNET.COM.AU>

At 11:42 11/03/03 +0100, you wrote:
>Dear stovers,
>
>I am surprised by the discussion about testing procedures. As Auke has
>pointed out, "lots has been written about stove testing and whole
>international meetings were devoted to this issue in the eightees".
>The result has been a document called:
>
>Finally. I propose a ban on the BTU (as well as the pound, inch etc.) as a
>unit on this forum. If I am correct it was in the fifties that
>internationally has been agreed to convert to the metric system. So as far
>as I am concerned there is no reason for existence anymore for an archaic
>unit as the BTU/pound, except maybe in history class.
>
>Best regards,
>
>Piet Visser

Heartily seconded

Piet Verhaart

From pverhaart at OPTUSNET.COM.AU Thu Mar 13 02:37:26 2003
From: pverhaart at OPTUSNET.COM.AU (Peter Verhaart)
Date: Tue Aug 10 18:30:18 2004
Subject: metric [was: Finally a stove testing procedure...]
In-Reply-To: <p05200f00ba93c4178c26@[128.83.86.30]>
Message-ID: <THU.13.MAR.2003.173726.1000.PVERHAART@OPTUSNET.COM.AU>

A British Thermal Unit is the energy required to raise one pound of water
one degree Fahrenheit in temperature.
1 lb = .453 kg
1 Deg F = 5/9 deg C
Specific enthalpy of water at ambient temperature C = 4.184 (from the top
of my head) kJ/kg.K

so 1 BTU = .453 * 5/9 * 4.184 kJ = 1.053 kJ eg a BTU is about 5 % more
than a kJ.

Peter Verhaart

At 10:53 11/03/03 -0600, you wrote:
>Before I go and find a convenient chart that gives some standard Btu
>-> metric conversions, does any one know of one that already exists?
>Or some benchmark values that they would like to see converted? I'll
>post what I find to the list.
>
>>Also thanks for the discussion of ditching the Btu - an embarrassment to me
>>and the U.S. (Our 18 year old grandson is visiting from Massachusetts and
>>we ONLY talk Joules and metric!) The effort of learning metric pays off
>>100fold when making calculations.

From Carefreeland at AOL.COM Thu Mar 13 12:38:36 2003
From: Carefreeland at AOL.COM (Carefreeland@AOL.COM)
Date: Tue Aug 10 18:30:18 2004
Subject: Fwd: [STOVES] Fwd: Re: [STOVES] standardize testing
Message-ID: <THU.13.MAR.2003.123836.EST.>

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From elk at WANANCHI.COM Thu Mar 13 07:57:08 2003
From: elk at WANANCHI.COM (elk)
Date: Tue Aug 10 18:30:18 2004
Subject: Fwd: Re: [STOVES] standardize testing
Message-ID: <THU.13.MAR.2003.155708.0300.ELK@WANANCHI.COM>

22 or 28 MJ/kg for charcoal......

You are right Peter... the book does indicate 30 MJ/kg. Our Vendor's Waste
Charcoal, with it's high ash is 22. Apologies for the confusion.

Incidentally, I have found that charcoal is actually fairly hydroscopic.
Some samples test to 17% moisture from material stored in the open. This
would both dilute (on weighing) and absorb energy up on burning....

Details- I digress...........

elk

--------------------------
Elsen L. Karstad
elk@wananchi.com
www.chardust.com
Nairobi Kenya

----- Original Message -----
From: "Peter Verhaart" <pverhaart@OPTUSNET.COM.AU>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Thursday, March 13, 2003 10:14 AM
Subject: [STOVES] Fwd: Re: [STOVES] standardize testing

> >Date: Thu, 13 Mar 2003 17:13:03 +1000
> >To: elk <elk@WANANCHI.COM>
> >From: Peter Verhaart <pverhaart@optusnet.com.au>
> >Subject: Re: [STOVES] standardize testing
> >
> >At 07:56 11/03/03 +0300, you wrote:
> >
> >
> >>We use Kcal/kg but can switch to MJ/Kg easily enough..... BTU is a
somewhat
> >>demographically restricted unit of measure I believe......
> >
> >Hear hear!
> >
> >
> >>And 22 MJ/Kg for pure wood charcoal?
> >
> >Isn't carbon around 30 MJ/kg? With wood generally containing 1 % ash and
> >yielding 25 % of charcoal, one could expect 4 % ash in charcoal. If the
> >remainder is carbon we would get around 28 MJ/kg.
> >
> >
> >>Should an uncovered pot be used if the test relies on measuring
evaporative
> >>(boiling) water loss? This would cause some problems for cookers such as
the
> >>Karve's- an enclosed stack of pots. The question here is; does a covered
> >>boiling pot lose less water than an open one?
> >
> >Yes, there is a water loss through diffusion of vapour statring far below
> >boiling point. It still needs all those MJ/kg heat input but at a lower
> >temperature where we can expect a higher heat transfer. Most if not all
> >cooking processes work at boiling point so a covered pot would give a
more
> >true figure.
> >
> >Piet
>
>

From tombreed at ATTBI.COM Fri Mar 14 11:42:43 2003
From: tombreed at ATTBI.COM (Tom Reed)
Date: Tue Aug 10 18:30:18 2004
Subject: Blue flames from WoodGas
Message-ID: <FRI.14.MAR.2003.094243.0700.TOMBREED@ATTBI.COM>

Dear Stovers...

Paul Anderson suggested I resend this.

> Tom,
>
> Your message (below) seems to have been sent only to Peter and to me. I
> suggest that you send it on to the entire Stoves list.
>
> Paul
>
> At 06:08 AM 5/3/02 -0600, you wrote:
> >Dear Peter:
> >
> >I have also been looking for a method to burn wood with blue flames - and
> >have found it - sort of...
> >
> >Kerosene is hard to burn with a blue flame too, but in mantle lamps and
> >stoves it is done by having "micro air" access to the kerosene vapors.
> >There is typically a tubular wick with air coming up through the middle
and
> >around the outside and passing through perforated plates to form a few
> >hundred small jets of air, drawn in by the chimney.
> >
> >We achieved the same thing with our natural draft inverted downdraft
stove
> >(below) by putting a 6 mm gap between the gasifier and chimney. We had
an
> >internal flame holder (gas wick, an unfortunate name)10 mm away that
> >constrained both the gas and the air to mix in a column of burning gas 10
mm
> >thick. This gave a blue flame.
> >
> >Without the flame holder the amount of combustion products was not enough
to
> >fill the chimney, resulting in poor draft and "spherical" combustion and
> >some yellow in the flame.
> >
> >I hope to see Paul Anderson in a week or two and explore this futher with
> >him. I hope that both of you will buy yourselves or visit in a store an
> >Alladin mantle lamp and study it.
> >
> >Comments? Keep in touch...
> >
> >TOM REED
> >
> >
> >
> >
> >
> >
> >
> >
>
> Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
> Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
> Dept of Geography - Geology (Box 4400), Illinois State University
> Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
> E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
>
>

From K.Prasad at TUE.NL Mon Mar 17 10:56:03 2003
From: K.Prasad at TUE.NL (Prasad, K.)
Date: Tue Aug 10 18:30:18 2004
Subject: Stove testing
Message-ID: <MON.17.MAR.2003.165603.0100.K.PRASAD@TUE.NL>

Dear stovers

I support both the Piets. Of course that is not surprising since we were all
members of the Woodburning Stove Group at Eindhoven in the Netherlands.

Prasad

-----Original Message-----
From: Peter Verhaart [mailto:pverhaart@OPTUSNET.COM.AU]
Sent: Thursday, March 13, 2003 8:21 AM
To: STOVES@LISTSERV.REPP.ORG
Subject: Re: [STOVES] Stove testing

Heartily seconded

Piet Verhaart

From Visser at BTGWORLD.COM Tue Mar 18 07:43:09 2003
From: Visser at BTGWORLD.COM (Piet Visser)
Date: Tue Aug 10 18:30:18 2004
Subject: Stove testing
Message-ID: <TUE.18.MAR.2003.134309.0100.VISSER@BTGWORLD.COM>

Dear stovers,

Thanks for your positive reactions, as wel as to my suggestions for the
test procedure as for the ban on BTU's.

Concerning the test procedures, we will make these available on our
website, so everybody interested can download them. For the time being we
have put the description for simple waterboiling tests as PDF file, but the
spreadsheets will follow shortly, as wel as a document with the formula's etc.

On the main page of BTG's website

www.btgwolrd.com

click on "links" and from the links given click on

www.cookstove.net

there click on "reports" and you will get a list of downloadable files.

For questions about the procedure etc. you can contact me directly or
through the stovelist.

Best regards,

Piet
(for the non-Dutch amongst you, to be pronounced as the English "Pete")

_____________________________________________________________

Phone : +31 53 489 2897
Direct : +31 53 489 2889
Fax : +31 53 489 3116
E-mail : Office@btgworld.com
Direct : visser@btgworld.com

From crispin at NEWDAWN.SZ Tue Mar 18 10:25:05 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:18 2004
Subject: Value of secondary air - is there a way to show it
Message-ID: <TUE.18.MAR.2003.172505.0200.CRISPIN@NEWDAWN.SZ>

Dear Stovers

Tom was asking if an experiment could be devised to show the value of
preheating the secondary air.

I have seen a stove built by John Davies (a coal gasifier) where he has a
removable sleeve over the outside top of the stove. This top portion admits
secondary air. By placing a sleeve over the top section of the stove the
secondary is preheated and changes nothing else on the stove.

He reports that 19% of the heat latent in the unburned fuel is transferred
to the pot without the sleeve, and adding the sleeve, which is about 120mm
high and 290mm in diameter, increases the heat transfer efficiency to 25%.
It does not touch or affect the shielding of the pot. It only preheats air,

The reason for this is better combustion and the release of more heat from
the gases. The sleeve has no apparent effect on the operation of the stove,
it only recycles heat escaping through the outside shell back into the fire
with the secondary air.

This experiment may fulfil the requirement described by Tom - viz. only
changing the secondary air temperature.

Regards
Crispin back from the ProBEC conference in Vereeniging

From robertoescardo at ARNET.COM.AR Tue Mar 18 16:03:49 2003
From: robertoescardo at ARNET.COM.AR (=?iso-8859-1?Q?Roberto_Escard=F3?=)
Date: Tue Aug 10 18:30:18 2004
Subject: metric [was: Finally a stove testing procedure...]
Message-ID: <TUE.18.MAR.2003.180349.0300.ROBERTOESCARDO@ARNET.COM.AR>

Back at home, revising old mails.
Try win-unit, free at http://unit-conversion.com/. A nice, handy pop-up,
with a "custom" feature included: You can convert anything to anything (As
long as you respect the dimensional equation, of course)
regards to all
Roberto.

----- Original Message -----
From: "Harmon Seaver" <hseaver@CYBERSHAMANIX.COM>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Tuesday, March 11, 2003 3:07 PM
Subject: Re: [STOVES] metric [was: Finally a stove testing procedure...]

> The best one I know of is Units
(http://sourceforge.net/projects/units/),
> unfortunately for most here it only runs on Unix. It seems to come bundled
with
> most linux distrobutions, and does pretty much any conversion you (or at
least
> I) can imagine.
>
> On Tue, Mar 11, 2003 at 10:53:08AM -0600, Robert T. Wyatt wrote:
> > Before I go and find a convenient chart that gives some standard Btu
> > -> metric conversions, does any one know of one that already exists?
> > Or some benchmark values that they would like to see converted? I'll
> > post what I find to the list.
> >
> > >Also thanks for the discussion of ditching the Btu - an embarrassment
to me
> > >and the U.S. (Our 18 year old grandson is visiting from Massachusetts
and
> > >we ONLY talk Joules and metric!) The effort of learning metric pays
off
> > >100fold when making calculations.
>
> --
> Harmon Seaver
> CyberShamanix
> http://www.cybershamanix.com

From pverhaart at OPTUSNET.COM.AU Tue Mar 18 17:05:34 2003
From: pverhaart at OPTUSNET.COM.AU (Peter Verhaart)
Date: Tue Aug 10 18:30:18 2004
Subject: Stove testing
In-Reply-To: <4.2.0.58.20030318133019.00be7b80@192.168.10.1>
Message-ID: <WED.19.MAR.2003.080534.1000.PVERHAART@OPTUSNET.COM.AU>

At 13:43 18/03/03 +0100, you wrote:
>Piet
>(for the non-Dutch amongst you, to be pronounced as the English "Pete")

And not as "Pee - at".

Piet (the other one)

From snienhuys at SNV.ORG.NP Tue Mar 18 23:16:03 2003
From: snienhuys at SNV.ORG.NP (Sjoerd Nienhuys)
Date: Tue Aug 10 18:30:18 2004
Subject: Beehive report
Message-ID: <WED.19.MAR.2003.100103.0545.SNIENHUYS@SNV.ORG.NP>

Dear Stovers,

Tom Miles posted the following paper on the web site:

" Beehive stove---" March 15, 2003

The paper looks at several issues related to the beehive briquette in Nepal,
Kumjung area.

Regards

Sjoerd Nienhuys
Senior Renewable Energy Advisor
SNV/N, Netherlands Development Organisation
P.O. Box 1966, Kathmandu, Nepal
Telephone: ++997-1-5523444
snienhuys@snv.org.np

From ventfory at IAFRICA.COM Wed Mar 19 08:35:39 2003
From: ventfory at IAFRICA.COM (Kobus)
Date: Tue Aug 10 18:30:18 2004
Subject: Ceramic charcoal stove
Message-ID: <WED.19.MAR.2003.153539.0200.VENTFORY@IAFRICA.COM>

To all stovers

I have been a lurker since Feb, 2002 and have developed an efficient charcoal stove that I have at a stage now where I am happy to share it with others, and quite frankly I am in need of assistance.

I think you could call it a batch feed, top lighted, ceramic lined charcoal stove, based on Tom Reed's IDD gasifier and the Rocket Stove. It consists of a 40cm high (15.75") "riser sleeve", 140mm (5.5 inch) inside diameter, with uncontrolled (constant) primary air entering through 6 (1 inch) holes in the bottom (also ceramic). Cross sectional area at exit point=154cm2 (0.17ft2), cross sectional area of inlet holes (total) =30.4cm2 (0.032 ft2).

My aim from the onset was to design an efficient charcoal stoves safe to use indoors as opposed to developing an efficient charcoal stove to reduce the dependence on charcoal and minimizing the impact on the natural resources from which it is made. Charcoals in South Africa are normally made from invader hardwoods (jungles occurring in water catchments) or commercially regenerated crops of the same alien species.

I have come to realize (from the testing of 2 prototypes amongst users) that urban communities have a need for a transitional modern fuel that is affordable and safe. Charcoal is affordable when used in my stove, due to the small amounts it uses and it does improve their way of life.

Here is what I know, excuse my lack of proper terminology:

1 - To gasify charcoal you need to supply 6 parts air to one part
charcoal and a further 6 parts air to one part producer gas to optimally
burn the gas mix. I must be achieving this criteria, because I have a
flaring blue flame, 5 minutes after torching with some paraffin.

2 - CO is released from biomass at ?609?C (1128?F), and CO and other
volatiles are released from charcoal at ?900?C (1652?F). Since I am only burning charcoal I am assuming that the latter would be applicable.

Approximate temperature of flue gas at exit point=?

I can only speculate. Damon Ogle did tests (ROCKET STOVES - CONTROLLING DRAFT, 17 AUGUST 2002) with different "riser" sleeve lengths and if I interpolate his exit temperature measurements of a 12 and 24 inch high "riser" for burning biomass, I get a temperature of 685?C (1265?F) at the exit point for the 15.75 inch high riser that I am using. This is also assuming 20% of air is allowed in (Dividing the total inlet hole surface area by the surface area of the "riser" at the exit point). I feel this temperature (685?C) is not reflective of charcoal burning with charcoal having a heating value of ?28 MJ/kg and wood (12% moisture) 18 MJ/kg, which is at least 50% higher than wood. So the 685?C (1265?F) more likely represents 1028?C (1882?F) at the exit point for charcoal burning. Would this be a fair assumption, bearing in mind no.3 below?

3 - A batch load of 400g of charcoal (75% carbon) burns as follows:
.gas burn for first 30 minutes, following 5 minutes of semi-transparent smoke release and yellow flames.
.remaining "coke" combusts over another 30 minutes (high constant
temperature)
.it then burns for another 30 minutes to white ash (decreasing
temperature).
.On average I would have to say that it gasifies and oxidizes 250 to 300
grams of charcoal per hour, or am I wrong?

Would any of this information be useful in calculating the A/F ratio? Is it
the required 12:1? (12 parts air, 1 part fuel). Please note that I do not provide secondary air as I am achieving a blue flame, but I do get the feeling that there are some unnecessary excess air sucked through.

As far as the body goes: 25L drum(0.38mm) on a stand, red oxide undercoat, ?45cm high, with a pot stand on top, and vermiculite compacted in between body and "riser".

Cheers

Kobus

From robert.wyatt at MAIL.UTEXAS.EDU Wed Mar 19 09:37:17 2003
From: robert.wyatt at MAIL.UTEXAS.EDU (Robert T. Wyatt)
Date: Tue Aug 10 18:30:18 2004
Subject: Value of secondary air - is there a way to show it
In-Reply-To: <029d01c2ed63$7f3c5200$2a47fea9@md>
Message-ID: <WED.19.MAR.2003.083717.0600.ROBERT.WYATT@MAIL.UTEXAS.EDU>

>adding the sleeve, which is about 120mm
>high and 290mm in diameter, increases the heat transfer efficiency to 25%.
>It does not touch or affect the shielding of the pot. It only preheats air

Sounds just like the "heat riser" from the exhaust manifold for
preheating carburetor air on an old car.

From crispin at NEWDAWN.SZ Wed Mar 19 09:41:42 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:18 2004
Subject: Ceramic charcoal stove
Message-ID: <WED.19.MAR.2003.164142.0200.CRISPIN@NEWDAWN.SZ>

Dear Kobus

Howzit?

Well done with the stove! It sounds great.

1. I think from Martheus' experience (GTZ Pretoria) with the Vesto and
adding charcoal, you should be able to add something like 200gm at a time
without a major problem so it can be refuelled as you cook if you like.

2. There is probably enough space to include a pot shield inside the 25
litre can to increase heat transfer. It will improve the overall
performance a lot compared with sitting a pot on top.

>Approximate temperature of flue gas at exit point=?

3. There seem to be two schools of thought on this: one that the gases
can be burned as close to the charcoal as possible to minimize the
'sideways' losses, or that it doesn't matter if they cool completely - gas
is gas. I am not sure you should worry about the temperature but you
certainly should worry about CO and getting the air mixed into it while
maintaining enough heat maintain a fire and get it to reduce to CO2.
Charcoal stoves can produce a lot of CO even when there is excess air.
Getting the air in as you describe may not at all ensure that it is mixed
and burned properly. Can you have the CO checked?

>On average I would have to say that it gasifies and oxidizes 250 to 300
>grams of charcoal per hour, or am I wrong?

4. That would be about equal to 7.5 gms of wood per minute which is quite
a low power. Have you tried it on larger pots like a No. 4 potjie? You
might try getting it to burn at a little higher rate to attract a larger
market.

>Please note that I do not provide secondary air as I am
>achieving a blue flame, but I do get the feeling that there
>are some unnecessary excess air sucked through.

5. Granted, but the warning still applies. It is hard to see what CO is
not burned. The advantage of having preheated secondary air is that you can
afford to use relatively small amounts of it to to stir things up above the
charcoal without losing gas temperature (or not much). Then excess air
comes in at the secondary stage and tends to burn everything. If your
excess air has to go through the charcoal it may well burn extra gasses off
instead of being available to be 'extra' to the CO above the fuel.

Where are you in SA?

Regards
Crispin

From ronallarson at QWEST.NET Wed Mar 19 19:59:16 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: Beehive report
In-Reply-To: <KGEALNHAOCPCAHEOEGHHGEFECCAA.snienhuys@snv.org.np>
Message-ID: <WED.19.MAR.2003.175916.0700.RONALLARSON@QWEST.NET>

Sjoerd and stovers:

The right reference for this site/cite is
http://www.repp.org/discussiongroups/resources/stoves/Nienhuys/Beehive%20Sto
ve.pdf

Tom Miles has done a great job in adding photos and longer reports like
Sjoerd's.

I haven't read this yet, but note that Sjoerd is using the 19-hole "holey"
briquette design. It looks quite complete, with reference to many of the
things we talk about. Thanks to Sjoerd for getting this to us.

Ron

>-----Original Message-----
>From: The Stoves Discussion List [mailto:STOVES@LISTSERV.REPP.ORG]On
>Behalf Of Sjoerd Nienhuys
>Sent: Tuesday, March 18, 2003 9:16 PM
>To: STOVES@LISTSERV.REPP.ORG
>Subject: [STOVES] Beehive report
>
>
>Dear Stovers,
>
>Tom Miles posted the following paper on the web site:
>
>" Beehive stove---" March 15, 2003
>
>The paper looks at several issues related to the beehive briquette
>in Nepal,
>Kumjung area.
>
>Regards
>
>Sjoerd Nienhuys
>Senior Renewable Energy Advisor
>SNV/N, Netherlands Development Organisation
>P.O. Box 1966, Kathmandu, Nepal
>Telephone: ++997-1-5523444
>snienhuys@snv.org.np
>
>

From ventfory at IAFRICA.COM Thu Mar 20 04:58:23 2003
From: ventfory at IAFRICA.COM (Kobus)
Date: Tue Aug 10 18:30:18 2004
Subject: Ceramic charcoal stove
Message-ID: <THU.20.MAR.2003.115823.0200.VENTFORY@IAFRICA.COM>

Crispin and other stovers,

I am fine, thank you for the encouraging remarks.

>1. I think from Martheus' experience (GTZ Pretoria) with the Vesto and
>adding charcoal, you should be able to add something like 200gm at a time
>without a major problem so it can be refuelled as you cook if you like.

I have tried that and yes continuous feeding works until the ash accumulation (2% - 10% I believe), interferes somewhat with the airflow, after 3 hours or so, unless you poke it, but that might damage the "riser". I normally brush the ash out the bottom holes with a 25mm paint brush.

>2. There is probably enough space to include a pot shield inside the 25
>litre can to increase heat transfer. It will improve the overall
>performance a lot compared with sitting a pot on top.

The riser is almost as tall as the can so whatever pot shield is added will have to be placed on top and not inside. I am working on a prototype that has a pot shield, but it will have to be wider than the diameter of the stove (>300mm) to accommodate the cooking habits (large pots & large meals) of the locals.

>Can you have the CO checked?

No, but I also feel it is a very important to check how well the CO is mixing with air.

>Have you tried it on larger pots like a No. 4 potjie? You
>might try getting it to burn at a little higher rate to attract a larger
>market.

I used a similar flat bottomed cast iron pot (because 3-legged potjies do not fit in my pot stand) and one litre of water boils within 7 minutes.

>It is hard to see what CO is not burned. The advantage of having preheated >secondary air is that you can afford to use relatively small amounts of it to stir >things up above the charcoal without losing gas temperature (or not much). Then >excess air comes in at the secondary stage and tends to burn everything. If your
>excess air has to go through the charcoal it may well burn extra gasses off
>instead of being available to be 'extra' to the CO above the fuel.

If I understand you correctly, it is advisable to have separate secondary air (preferably pre-heated) in small amounts enter above the charcoal level and at the same time reduce the amount of excess air entering through the coals to effect a clean burn with less CO in flue gas?

"Riser" material is easy to pierce, perhaps by carefully drilling a couple of holes (one hole at a time, to see or measure the effect) in the sides above the level of the charcoal could allow some warm air in. I'll just have to make sure that the drum is not sealed up so as to allow air in from the outside as well as preventing vermiculite from falling through the holes.

There are probably other ways of supplying preheated secondary air, I'll think about it, thank you for the advice.

>Where are you in SA?

I live in Pietermaritzburg, KwaZulu Natal and work in Hilton.

Regards

Kobus

From crispin at NEWDAWN.SZ Fri Mar 21 11:27:33 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:18 2004
Subject: Testing in Vereeniging
Message-ID: <FRI.21.MAR.2003.182733.0200.CRISPIN@NEWDAWN.SZ>

Dear Stovers with testing interests

POINT 1
With reference to the heat content of wood, Daniel wrote:

DD These woods all fall between 7143 and 6765 btu per pound "air dry". The
key words here being "air dry".

I think that air-dried wood is acceptable at 16 MJ/Kg give or take a little.
There are some things which I was told at the ProBEC Vereeniging conference
which are far more important than a quibble over a little heat content, real
as that debate is.

POINT 2
The ProBEC conference was aimed at exploring current trends in devices and
commercialization or dissemination to try for greater impact with programs
and products. Quite a number of stoves were on display, though no 3-stone
fires were built.

Testing was shown, with Grant Ballard-Tremeer in the wings but in action on
the benches.

Something I was told which everyone with experience seemed to agree was
that:
1) comparative testing should be done simultaneously with identical pots,
2) all boiling tests were to be done with the pot lid off "because otherwise
it is a test of how well the pot lid fits" which I find unbelievable. I
want to see an ordinary pot with a steam-tight lid before I accept that one.
Leaving off the lid only makes the calculation more difficult and is not
realistic. I was told that testing in the lab is not supposed to be
realistic. Huh? Having the lid off forces the stove to be run at a higher
power which reduces efficiency and heat transfer, hiding possible real
improvements in stove desisgn. Standard household management training
solves that lid-loss immediately.

At ome time, four different stoves were tested simultaneously using a No.2
three-legged cast iron pot with the legs cut short (a rare sight in real
kitchens). It was a 'power test' or rapid boiling test. As readers will be
aware I have reservations about power tests because clever manipulation of
the stove, the fuel management or the building of an entire stove to win
such a test is easy and meaningless. In any case, these four stoves were
lit at once went on with the boiling.

Of significance is that at the report back session the group agreed
universally that the stoves should in fact be tested with the pot for which
they were designed. This may sound a little obvious, but some stoves were
obviously not designed to cook with a round bottomed cast iron pot with sawn
off legs.

The Malawian Maendeleo, a small clay sheltered fire with an open door was
one stove that provoked my interest. It has real possibilities for saving
fuel in a community that is windy and in which clay working skills are
common. It is really cheap. It is designed to use flat bottomed pots
sitting on three bumps to give the correct distance between the pot skin and
the stove body. During the test with the round bottomed pot it was unable,
ever after 35 minutes, to boil 2 litres of water even though the fire was
going well and the inside wall was re-radiating beautifully, heating
incoming air as it entered the door. Holding my hand over the doorway
reduced the free-flowing air and immediately improved the heating rate. It
was clear that pot-stove gap was too way too big.

I removed the No. 2 pot-bellied pot (about 7 kg) and put on 2 litres of cold
water in a lidless flat bottomed pot of a similar dimension (about 5.8 Kg of
cast iron). In 23 minutes it boiled the two litres. This was rightly taken
by the group to be an example of the right pot being used during testing in
order to establish whether or not one might include it in a program. The
pot-bellied pot might otherwise have shown that "this stove cannot boil a
pot of water".

Testing of a stove that is made to work in a particular environment, such as
a Maendeleo, should include the pots for which it was intended to be used.
If one wanted to test a Maendeleo using a three-legged pot, it should be
sized and shaped to accept it, which is exactly what would happen in the
field when the stove body was formed by the owner.

POINT 3
The group agreed, at least in informal conversation, that the pot itself sho
uld be left out of heating calculations. I find this bizarre and wholly
unscientific. The final 'number' by which stoves are rated is usually the
"PHU" or percentage heat utilized. In a power test, the PHU is necessarily
less that it would be in a long simmer because heat invested in the pot is
not reclaimed during the brief measuring period. In order to show the
importance of this I did a well measured test using the Vesto and the No.2
cast iron pot (for which the stove is not designed) with no lid. I
fashioned a wind shroud out of old aluminum foil around some 80% of the
pot's circumference. It boiled in 9.5 minutes from lighting the match.

The ambient temperatire was 25 C.
The mass of the pot was 7 kg approx
The mass of water was 2000 gm exactly
The fuel burned (at maximum possible rate) including lighting up and stove
heating losses etc was 253 gm of wood which everyone agreed was not very
close to air dry but I used 16MJ/Kg anyway. The avg was 26.6 gm/minute of
fuel. The fuel might have been 20% WMC.

"Standard" PHU calculation:
Fuel used 0.253 Kg x 16MJ/kg = 4,048,000 Joules

2kg water x 95-25 deg temp rise x 4.2 J/Cal =
2000 * 70 * 4.2 = 588,000 Joules

PHU "ignoring the pot" = 588,000/4,048,000 = 14.53%

The cast iron pot weighed 3.5 times as much as the water and was obviously
heated in the process. Cast iron is not a very good conductor of heat so I
estimate the external skin temperature to be 130 and the internal skin
temperature to be 100. The part of the pot above the waterline is much
hotter but I will leave that out. The effect when the pot is fuller varies.

Average pot temperature (final) = 115 C (at least)
Delta T = 115-25 = 90 C
Mass of pot = 7 kg
Heat in cast iron at 300 deg Kelvin = 420 J/Kg/Deg K
Heat in the pot collected from the fire and not passed on to the water =
7*420*90= 264,600 Joules

PHU "including the pot" = (588,000+264,600)/4,048,000 = 21.06%

That is an apparent increase of 45% in PHU value! It is unbelievable that
any PHU figures from rapid boiling tests have meaning unless the pot has
been included in the calculation. Suppose you are cooperating loosely with
someone on the other side of the world and you don't have simlar pots?
Suppose the other person uses a 500gm aluminum pot and does the same test
using a different stove and also takes 9.5 minutes:

PHU "including the aluminum pot" = (588,000+(905*0.5 kg*approx 75
deg))/4,048,000 = 15.36%

Arguably the test in the first stove would have been concluded much faster
using the aluminum pot (just under 7 minutes, using some 184 gm of wood = a
PHU of (588,000+(905*0.5 kg*75 deg))/2,953,000 = 21.06%, the same as before.

Disregarding this theoretical aluminum pot would give a PHU of
588,000/2,953,000 = 19.91%.

POINT 4
Calculating for any water boiled out during the power test would have added
to the PHU value as well. Having the lid off only confounds things. I
didn't weight the water that boiled and drifted off the surface. I was
trying to make a point about the PHU and a pot weighing more than 3 times
the water.

I can't care what people are 'all doing' if it gives meaningless or highly
misleading PHU results, and those results are later cited off-handedly to
'rate' approaches and compare stove configurations.

THE SIMPLEST MEANINGFUL TEST
- Fuel burned, water content known and correct heat value used
- Mass of water boiled in a closed pot so evaporation is negligible and loss
does not need to be measured
- Water temperature rise during the test
- Mass of pot heated using some 'standard' temperature value given for heat
conduction through the wall, 420 for cast iron, 903 for sheet aluminum, 450
for steel (Joules/Kg/Deg C).

This comes close to a meaningful application like making tea or preparing
porridge in a real pot on a real stove.

With regards to all
Crispin

From crispin at NEWDAWN.SZ Sat Mar 22 03:04:46 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:18 2004
Subject: Testing in Vereeniging
Message-ID: <SAT.22.MAR.2003.100446.0200.CRISPIN@NEWDAWN.SZ>

Dear Elk

>Thanks for your comments on testing Crispin. I can sympathise with
>you on the pot issue.....

I have more to say on this but the message was long enough!

>I've never even SEEN one of those cast iron pots here in
>Kenya (outside of a South African's home here, that is).

There are a lot around the region, but as they are not very fuel-efficient
and expensive to buy, there are very few in urban areas these days. In
Lesotho they use very large three-legged pots.

>You are advocating a 'Time to Boil' test, right?

Not really. I just want a test that is a fair comparison and there is too
much flim-flam in this testing business. It is more a test of the operator
than the stove and this is inherently misleading.

To know the effectiveness of heat transfer, there should be a continuous
boiling test where a pot that is _already_ boiling is kept boiling without a
lid, but the water level and diameter/depth ratio affects the test result.

To know how fast something boils a given quantity of water is misleading
because people would probably prefer to boil water rather than to boil it
very rapidly. Stoves are usually less efficient at flat out power and again
this is misleading as a measure of the effective use of fuel during
'cooking' which is by far the greatest amount of the time a stove is used.

> This may lead to
>difficulties with measuring residual fuel?

I think measuring fuel used can be overcome in a simple testing setup.

>To this end, I still like the water evaporation test- with an standardised
>open pot- that measures time to boil, duration of burn (to end of steaming)
>and assumes complete combustion of a measured quantity of fuel with no
>addition.

This would be a problem with stoves designed to burn on one end of a stick,
I think. You can't 'load it' with fuel.

I would be OK with a boiling test that measured fuel consumption and work
done in a _closed_ pot so that it did not reward stoves with very high power
and penalize ones with low power that couldn't boil out a lot of water
getting it up to 'boiling temperature'. Notice there is no time measurement
in this, only effectiveness in using fuel.

A time-independent PHU has real value if the test simulates cooking. A
lid-off test wouldn't. A lid-on test would.

A time-dependent power test is a meaningful test of a stove's ability to
generate heat and deliver a boiled pot in a short time. That is quite
independent of a PHU test, in my view, though I suppose one might be
interested in the PHU anyway. However, it is misleading to use a rapid
boiling test to get a PHU figure for a stove. For example the charcoal
stove Kobus is testing might not be able to boil a No.2 potjie with a open
lid, but I'll bet it has a really high PHU at low power using a flat
bottomed aluminum pot. It isn't very difficult to get a PHU of 45% with a
small fire and a skilled operator, but that is hardly a power test.

If you like, perhaps the boiling test with lid off is an example of a
minimum power for a useful stove. It is pretty easy to weight the pot before
and after, and get the stove fuel mass by subtraction as well.

Regards
Crispin

From ronallarson at QWEST.NET Sat Mar 22 13:19:41 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: FW: [ethos] Fw: justa pix
Message-ID: <SAT.22.MAR.2003.111941.0700.RONALLARSON@QWEST.NET>

To all members of "Ethos" and "stoves":

Apologies for asking you to read backwards through 5 messages. Working
from bottom to top we have:

4. >>>> Thursday message from Dean Still to the "Ethos" list showing 2
photos of a stove that I found very beautiful.

3. >>> My off-line response to Dean, same day, asking 6 questions.

2. >> Response off-line back yesterday from Damon Ogle answering these
questions very fully (this is the part of most importance to all stove
designers, I think).

1. > My asking yesterday for permission to post our off-line communication
and asking a bit more.

0a. (no ">") Yesterday from Damon (also got Ok from Dean) encouraging a
post and some more answers.

0b. I have since been assured by Tom Miles: "They are quite good pictures.
I'll see if I can get them up this morning."

0c. The members of "Ethos" today have also heard a comment from Doug
McCorkle [mccdo@iastate.edu] on this exchange, saying:

"In response to the discussion about a more evened surface temperature
on
the justa I was wondering if you would be interested in the work that we
have
done in the Bryden lab? We have the ability to optimize the baffle placement
in a plancha style stove. Also, we have already completed many runs of this
algorithm and have suggestions for baffle placement in a plancha that is
approx. 21" x 21". If anyone would be interested in this information feel
free
to contact me and I can send specific dimensions and placement locations for
baffles. Also, if the above size plancha is not what is being discussed
below
please send me the dimensions and location of the rocket elbow and chimney
and
I will try to run it through our algorithm. I can't promise a lightning fast
response but I should be able to get an answer for future work."

I hope Doug will keep both "Ethos" and "Stoves" informed on his
computations of the optimum baffles. I gather than none was used on the 2
stoves whose photos we have seen. I would also appreciate hearing from
Doug, Damon, Dean, Mike Hatfield, Don O'Neil, Stewart Conway or anyone else
on the possible advantages and the construction techniques for using an
alternative "inverted funnel" design to try to achieve uniformity.

But I am not at all sure that users in this area would want surface
uniformity - and hope all can address that issue as well.

To summarize, the things I find most interesting about these stoves are:

1. very attractive finished product - and done at least in this case by the
homeowner. The total cost is not yet clear - but the main $60 (subsidized
sometimes down to $30) seems very reasonable. I am anxious to hear more
from everyone on the importance of adding extra costs to improve the
appearance. I wonder if others think this is a very handsome stove - and
better than most we see for sale of modern design at 10 times the likely
price? We all know appearance is important - but how do we accomplish this
at acceptable cost? Is homeowner finishing (and starting) the right way?

2. This dialog enables us to talk more about both what users want in
surface temperature uniformity and how to achieve it.

3. Recent talk about energy efficiency computations. This stove doesn't
lend itself to the ongoing discussions on "stoves" about measuring
efficiency (and whether pots should or should not be lidded during testing).
How should we be measuring these stoves?

Thanks to Dean, Damon, Doug and Tom for much useful information.

Ron

-----Original Message-----
From: Damon Ogle [mailto:monogle@oregoncoast.com]
Sent: Friday, March 21, 2003 8:21 PM
To: Ron Larson
Subject: Re: [ethos] Fw: justa pix

Ron,
Feel free to post wherever you think it might be useful. Edit as you
see fit.
Mike Hatfield at Apro might have some more info on cost of platform. Re:
inverted
pyramid under griddle surface --Don gave me good drawings and temperature
gradients
on the back of a napkin in Seattle. I kept it, but can't find it. Probably
best to
contact Don directly. Re: baffeling -- I don't remember any baffling under
the
planchas. I took some pictures and will look thru them to make sure. They
used a
24"x24" 1/8" mild steel sheet bent down 1" along ech edge and welded to give
a
22"x22"plancha. We are recommending changing to a more rectangular shape
for better
heat transfer and possibly fewer warping problems.

Damon

Ron Larson wrote:

> Damon (cc Dean) - Thanks for this great reply.
>
> I really think that this response would be of great interest to
the full
> Ethos group (and also to Stoves). Not sure of the proper etiquette for
> doing that - but must start with Damon's OK.
> If OK - I'd still like to know more about:
> 1. the cost of adding the tiles - even if a guess separately for
the
> tiles and labor. I am just terribly impressed about how high-quality this
> now looks. Thansk very much for the very complete costing. (and maybe
need
> more on the cost of the platform)
> 2. Something about the out-of-sight baffling.
> 3. More on Don O'Neil's inverted pyramid approach and how uniform
he can
> get - and whether it would be wanted - and if we know enough to give the
> owner whatever she wants.
> 4. More on AHDESA.
>
> I'm willing to do the work of editing - if that would be helpful. If also
> "stoves" seems appropriate, we need also to get Tom Miles to put your two
> pictures in his picture file.
>
> Again - nice work and nice response.
>
> Ron
>
> >-----Original Message-----
> >From: Damon Ogle [mailto:monogle@oregoncoast.com]
> >Sent: Friday, March 21, 2003 5:11 PM
> >To: Ron Larson; Dean Still
> >Subject: Re: [ethos] Fw: justa pix
> >
> >
> >Hi Ron, Damon here.
> >Let me take a stab at answering your questions.
> > 1. These stoves are part of an AHDESA stove project near
> >Tegucigalpa. Total cost
> >of basic stove is about $60. This breaks down to $10.50 for the
> >plancha (griddle),
> >$7.58 for the elbow (pottery now, but our new baldosa elbows
> >should be less then $1),
> >$4.37 for chimney, $14.55 for skilled labor (the mason/stove
> >technician), $15 for
> >transport (and maybe some overhead?) , and $8 for training and
> >inspection (very
> >important). The family must also build a suitable platform for
> >the stove and provide
> >some basic materials and unskilled labor for the mason. Rotary is
> >involved in some
> >projects and I think they and Ahdesa subsidise about half of the
> >cost of the basic
> >stove. Bells and whistles (in this case tiles) are paid for by
> >the stove owners. In
> >this case the tortilla lady's husband did the tile work on his own.
> > 2. The technicos (stove masons) are able to do about two
> >stoves a day and they have
> >4 or 5 techincos working now. I'm not sure of total numbers but I
> >think two or three
> >thousand have been built in neighborhoods around Tegucigalpa in
> >the last couple of
> >years.
> > 3. No hard numbers on wood savings, but the lady whose stove
> >is pictured claims
> >that her wood costs went from 280 limpiras per day down to 30 or
> >40 per day after she
> >installed the stoves, (I think there are about 8 limpiras to the
> >dollar). She has three
> >stoves (only the first of which was subsidized) and about 6 women
> >are employed making
> >tortillas for the market, so the stoves are burning all day long.
> >Most house wives
> >(cooking for meals only)will tell you that they use 1/3 of the
> >fuel they used before.
> >These are probably WAGs but I believe the savings are at least 50%.
> > 4. There is a hot spot , but the entire surface seems to
> >remain hot enough to cook
> >tortillas. They have learned to juggle the tortillas so that they
> >don't burn.
> > 5. The top of the rocket elbow is about 2" below the bottom of
> >the plancha. The
> >insulation is wood ash and when installed is beveled up to about
> >1" below the plancha
> >for most of the path. Ash tends to settle and in most of the
> >older stoves we inspected
> >the gap was greater we wanted to see. Maintaining the proper gap
> >is a problem for
> >which we have not yet found a good solution.
> > 6.Don O'Neil uses a version of the inverted pyramid in his
> >Helps Stove in
> >guatemala. The side of the elbow toward the chimney is about 2"
> >lower than the rest of
> >the elbow sides and a gradual "ramp" slopes up to a 1" gap below
> >the plancha at a point
> >about 2/3 of the way to end of the plancha. He uses pumice for
> >insulation and gets a
> >much better heat distribution using this configuration.
> >
> >A couple of other observations.
> > This is hard to quantify, but the quality of life goes way up
> >for people using the
> >"justas". Before the stove is installed, the kitchens tend to be
> >dark, and grimey with
> >lots of sooty cobwebs everywhere. Everything including the cook
> >and her clothing are
> >sooty and smell of smoke. After the stoves are installed, the
> >cooking areas ted to get
> >cleaned and painted and both clothing and attitudes tend to be brighter.
> > I don't know about CO emmisions, but visually the stoves seem
> >to burn very clean.
> >When you look at the chimney from outside the house it is almost
> >impossible to tell
> >whether the stove is burning or not. If you look very closely you
> >can see the heat
> >waves.
> > These are very good stoves, but the target group seems to be a
> >somewhat middle
> >class family (by C.A.standands). I certainly think we should
> >continue to build as many
> >"justas" as possible, but we should also try to target the poorer
> >part of the
> >population by developing a much cheaper simple stove for people
> >who will never be able
> >to afford a $60 stove.
> > Lets do both.
> >
> > Damon
> >
> >
> >Ron Larson wrote:
> >
> >> Dean:
> >>
> >> Thanks for the two pictures of the "Fancy Justa" (and a
> >reminder about your
> >> grandmother and Quakers).
> >>
> >> I too was impressed by the beauty of the stoves. The
> >ceramic tiles are
> >> wonderful looking. Several questions (maybe for Damon?):
> >>
> >> 1. What is the cost of these units - and what
> >proportion of the cost is in
> >> making the stove a work of art?
> >>
> >> 2. What is the method of production? All knowledge
> >transferred to local
> >> artisans and in full scale production? How many out there like
> >these two?
> >>
> >> 3. Any way to talk about efficiency - or
> >wood-consumption in comparison to
> >> the stoves they are replacing?
> >>
> >> 4. It seems in Picture #1 that there might be a hot
> >spot that is being
> >> avoided. Is this usually used for a pot - or would the users
> >prefer a more
> >> uniform surface temperature? It looks like maybe the tortillas (right
> >> word?) are moved closer to the (presumably cooler) exit pipe as they
are
> >> finishing cooking - is a varying surface temperature maybe considered
an
> >> asset by the cooks?
> >>
> >> 5. What sort of flame path is underneath and out of
> >sight? (What sort of
> >> baffling?)
> >>
> >> 6. Have the developers ever tried using an inverted
> >pyramid for the flame
> >> path - in an attempt to get greater surface temperature uniformity? (I
> >> don't think that the Ethiopian enjira could be cooked on this
> >surface - as
> >> the typical diameter is about 60 cm.
> >>
> >> Thanks in advance for any answers - and thanks for sharing the
pictures.
> >>
> >> Ron
> >>
> >> >-----Original Message-----
> >> >From: owner-ethos@vrac.iastate.edu
> >> >[mailto:owner-ethos@vrac.iastate.edu]On Behalf Of Dean Still
> >> >Sent: Thursday, March 20, 2003 4:53 PM
> >> >To: ethos
> >> >Subject: [ethos] Fw: justa pix
> >> >
> >> >
> >> >Really nice Justa stoves. I want one! Pictures taken by Damon Ogle...
> >> >
> >> >Best,
> >> >
> >> >Dean
> >> >
> >> >PS: My grandmother, who died at the age of 102, lived through many
> >> >wars. She
> >> >once told the grandkids that everytime there was a war in her
> >country she
> >> >gathered all the family together and they did a very thorough Spring
> >> >cleaning. After the First World War she became a Quaker because
> >as soon as
> >> >the fighting stopped Quakers from England brought food to the starving
> >> >Germans.
> >> >
> >> >Subject: justa pix
> >> >
> >> >
> >> >
> >
> >
> >
> >

From ronallarson at QWEST.NET Sat Mar 22 13:58:44 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: SR 2003
In-Reply-To: <NGBBKDEHILILFNJPHEFIMEHFCKAA.ronallarson@qwest.net>
Message-ID: <SAT.22.MAR.2003.115844.0700.RONALLARSON@QWEST.NET>

Stovers:
This is an announcement of an upcoming conference - with already a sizeable
stove component. Anyone else interested? Some more questions below.

I goofed on Wednesday by trying to send attachments - and so am resending
as I figured out my error. The three intended attachments are now at the
end.

Ron

>-----Original Message-----
>From: Ron Larson [mailto:ronallarson@qwest.net]
>Sent: Wednesday, March 19, 2003 1:08 PM
>To: Stoves Discussion List
>Cc: Steve Troy
>Subject: FW: SR 2003
>
>
>Stovers:
>
> The following exchange is pretty well self-explanatory. We
>in the world of stoves are being asked if we wish to be a larger
>and more structured part of what is turning out to be a fairly
>large (first-time - but likely to be continuing) meeting scheduled
>in Boulder Colorado for October 1 through 4. Already at least 4
>or 5 of the "stoves" list have submitted papers or ideas - as you
>will see below, and in the attachments. Thre will definitely be a
>stoves presence at this meeting - the question is whether we
>should try even harder to make it a bigger thing? All receiving
>this are especially asked to submit papers and or volunteer to be
>parts of panels.
>
> Steve Troy is the owner of www.thesustainablevillage.com
>(former owner of Jade Mountain) and a good friend of the stoves
>group (I urge all to look at his very interesting web site). I
>have attended some meetings on this Conference subject, but could
>not make the last one on Monday night when the three attachments
>were developed. (I have not sent similar ones on exhibits and plenaries.)
>
> I can put up a few people - with first rights going to Tami
>Bond (who probably will be hugely busy with her classes at the
>University of Illinois).
>
> So let me know either on-list or off-list on what we should
>be trying to do. We don't have enough yet for a full-blown
>meeting - but we have a good start. How should we structure the
>stoves part? Do we want to meet some with other "tracks", etc
>etc. Do you want to set a period either before or after also?
>
> The advantage of our doing this in Boulder in October is
>that there are already several dozen people working on this and we
>are apt to see many faces who need to hear more about our world.
>
> Ron
>
>ps - as an aside - The Denver area (and especially my house) are
>in the midst of the worst snow storm I have ever seen. It has
>snowed pretty steadily since Monday night (still doing so) and we
>have at least 4 feet on average and drifts much higher (some of
>course in my driveway). Oops - I shouldn't have said "snow" since
>it sometimes happens by Oct. 1 - but not usually that early - more
>apt to be a very pleasant time of the year (and we had
>temperatures in the 70's (F - 20's C) last week). I have even
>seen some spring flowers out already - many broken trees and
>10,000 without electricity here right now. We have lost our cable
>TV signal - but are in good shape except for not being able to
>drive until we shovel out. Good time to catch up on my e-mail -
>which I shall try to do.
>
>
>-----Original Message-----
>From: Steve Troy [mailto:steve@thesustainablevillage.com]
>Sent: Wednesday, March 19, 2003 8:54 AM
>To: Ron Larson
>Subject: RE: SR 2003
>
>
>>RWL: We might be able to do, but everyone is hurting right now.
>>But I think there are plenty of local Coloradans, born in developing
>>countries,
>>with a big interest in trying to help back home. I don't think we
>>need to bring in lots from outside.
>
>No I don't think we need to; but, it could be good if we get the
>dollars for it, GVEP has already expressed interest in sponsoring as
>well as Verizon and Energy House.
>
>>I am also thinking of the small group from Kafa, Ethiopia - who
>>might be able to justify some personal funds to subsidize a friend
>>coming. But do we
>>think that we can solve the visa problem?
>
>I'm not sure but we I think we should suggest people to start the
>process right away - it will probably at least take longer than
>normal.
>
>>I can't think of any ready source of travel funds - but will start
>>talking it up. We should try to generate a list of other activities
>>so that the visit is not justified on the basis only of 4 days in
>>Boulder.
>
>We already have a 2-day RMI program on Systems Thinking and the 2-day
>NREL pv 101 course. Maybe we could offer a 2-day stoves track. We're
>thinking of having these just before or just after the conference.
>Any suggestions on place? We can't use CU because classes will be
>back in session. NREL?
>
>>(RWL): I will send out a general invitation soon to the stoves
>>list - for speakers - later for attendees.
>
>Great!
>
>>Can you give some more thoughts or assurances on the amount of time
>>a stoves "track" might have? Could 10-15 stoves people have room to
>>meet?
>>(others welcome to join in of course).
>
>We've talked about having several tracks so that people into a
>certain theme wouldn't have as much conflicting overlap (we'll
>probably have at least 7-8 simultaneous workshops. Here's what we
>have so far that could relate to stoves:
>
>Workshops
>Designing and Building Vernacular, Fuel Efficient, Low Emission
>Cooking Stoves (2 hours or 0.5 day)
>Dean Still, Director, Aprovecho Research Center
>Development and Use of the Baker Sawdust Injection Burner and
>Homemade Castable Refractories to Build and Fire Alternative Ceramic
>Kilns
>Lowell Baker and Hernandez, University of Alabama
>Micro-enterprise and community based agro residue fuel briqueting as
>a sustainable alternative to wood and charcoal use in developing
>nations
>Richard Stanley, The Legacy Foundation
>Practical Solutions Through Low-Tech Solar Cookers and Other
>Sustainable Devices - Experiences and Strategies in Nepal, Mongolia,
>Peru and Bolivia
>Allart Ligtenberg, Los Altos, CA
>Production of Biodiesel and Biofuel
>Andrew Azman, University of Colorado, Boulder
>
>Talks
>Twenty Five Years Developing Vernacular Stoves
>Dean Still, Aprovecho Research Center, Cottage Grove, OR
>Solar Cooking Technologies: Examples of Success and Expanded Applications
>Terry Grumley, Executive Director, Solar Cookers International,
>Sacramento, CA
>The New Papillon Solar Cooker
>Jochen Dessel, Sprockh?vel, Germany
>An Arranged Marriage: Solar Cookers and Fuel-Efficient Stoves
>Barbara Knudson, Walden University, Minneapolis, MN
>Simplicity, Efficiency, Effectiveness: A Case for Engineering Design
>of Biomass Cookstoves in Developing Nations
>Kenneth Bryden, Iowa State University, Ames, IA
>CU Biodiesel Fueling the Future
>Andrew Azman, University of Colorado, Boulder
>
>
>--
> ===============================================================
> The Sustainable Village, LLC 717 Poplar Ave.
>Boulder, CO 80304
> "Resources for the Developing World"
> email: steve@sustainablevillage.com web site:
><www.sustainablevillage.com>
> voice 303-998-1323 ext. 100, fax 303-998-1323
>
>

Three attachments follow:
Attachment #1 - Short version of program:

SUSTAINABLE RESOURCES 2003

WEDNESDAY OCTOBER 1
5:30 p.m.-6:30 p.m. Paolo Lugari Keynote on Gaviotas (open to public)

THURSDAY OCTOBER 2
8:00 - 8:30 Welcome
8:30 - 9:30 Opening Panel
9:30 - 10:00 Break
10:00 ? 12:00 Sessions and Workshops
12:00 ? 1:30 Lunch (on your own) and Exhibits
1:30 - 2:30 Keynote
2:30 ? 3:00 Break
3:00 ? 5:00 Sessions and Workshops
5:00 ? 7:00 Exhibits and Reception
7:00 ? 8:00 Public Lecture: Matthew Fox

FRIDAY OCTOBER 3
8:30 - 9:30 Keynote
9:30 - 10:00 Break
10:00 ? 12:00 Sessions and Workshops
12:00 ? 1:30 Lunch (on your own) and Exhibits
1:30 - 2:30 Keynote
2:30 ? 3:00 Break
3:00 ? 5:00 Sessions and Workshops
5:00 ? 7:00 Exhibits and Reception
7:00 ? 8:00 Public Lecture

SATURDAY OCTOBER 4
8:30 - 9:30 Keynote
9:30 - 10:00 Break
10:00 ? 12:00 Sessions and Workshops
12:00 ? 1:30 Lunch (on your own) and Exhibits
1:30 - 2:30 Keynote
2:30 ? 3:00 Break
3:00 ? 5:00 Closing Panel

Attachment #2 - Lectures:

LECTURES 03/18/03

APPROPRIATE TECHNOLOGY: LOW TECH, HIGH IMPACT
The Filtron
Ron Riveira, Potters for Peace, Nicaragua
Twenty Five Years Developing Vernacular Stoves
Dean Still, Aprovecho Research Center, Cottage Grove, OR
Solar Cooking Technologies: Examples of Success and Expanded Applications
Terry Grumley, Executive Director, Solar Cookers International, Sacramento,
CA
The New Papillon Solar Cooker
Jochen Dessel, Sprockh?vel, Germany
The Life Box
Paul Stamets, Fungi Perfecti, LLC, Olympia, WA
An Arranged Marriage: Solar Cookers and Fuel-Efficient Stoves
Barbara Knudson, Walden University, Minneapolis, MN
Simplicity, Efficiency, Effectiveness: A Case for Engineering Design of
Biomass Cookstoves in Developing Nations
Kenneth Bryden, Iowa State University, Ames, IA
CU Biodiesel Fueling the Future
Andrew Azman, University of Colorado, Boulder

BIOMIMICRY - LEARNING FROM NATURE
A New Relationship with Forests
Roald Gundersen, Architect
Biological Structures
Chris Piper, Labrador, Australia
Biome Design
Michael Bertin, Boulder, CO
Phytoremediation: A Low-Cost, Sustainable Technology for Environmental
Clean-Up
Anu Ramaswami, University of Colorado, Denver
Passive Treatment of Acid Mine Drainage Using Constructed Wetlands:
Affordable and Maintainable Solutions for Developing Communities
Joseph Ryan, University of Colorado, Boulder

BRIDGING THE TECHNOLOGICAL GAP
Engineering Solutions Across the Divide: The Silicon Valley/India
Development Technology Center
Kyle Eischen and Jon Guice
Cultural Preservation and Community Knowledge in Tibet and the Himalayas
Using Digital Technology
David Germano, University of Virginia
New Telecom Technology for Development
Ken Novak, VP Network Services
Innovative Sustainable Technologies to Combat World Poverty
A. Jagadeesh, Nayudamma Center for Development Alternatives, India
Thinking Together for the Common Good
Alexia Parks, Boulder, CO

ECOTOURISM THAT WORKS
Campesinos, Conservation and Your Vacation: Community-Based Ecotourism and
Sustainable Tourism Certification in Costa Rica
Anne Becher and Beatrice Blake
Poverty Alleviation Through Ethical and Eco Tourism
Michael Simkin, The Manda Wilderness Project, London, UK
Using Environmental Technology to Promote Sustainable Tourism
Edna Aguinaga, Consultorai Balam, Mexico

FEEDING THE WORLD
Global Impact of Mushroom Cultivation on Human Welfare: NonGreen Revolution
Prof. S.T. Chang

More Food Equals More Forest - A Sustainable Model for Rural Development in
the Tropics
Florence Reed and Bruce Maanum, Sustainable Harvest International,
Portsmouth, NH
Permaculture - Understanding Its Roots
Bill Melvin, Ecospace Environmental Design, Boulder
Alternative Marketing of Organic Agriculture Products Through Organic
Bazaars
Alexander Daniel, President, Institute for Integrated Rural development,
India
Sustainable Micro-Farming
Devon Patillo
Poverty Alleviation Using Integrated Waste Management & Farming Systems
George Chan and Jon R. Schulz

INFRASTRUCTURE AND SHELTER ALTERNATIVES
The Village of Hope
Masum Azizi, AZIZI Architects, Newport Beach, CA
Preserving and Building on Traditional Skills
Andre Alexander and Nyima Tsering, Tibet Heritage Fund

LEARNING FROM NATIVE CULTURES
Native American Communities: A Case Study - Jemez Pueblo, NM
Governor Raymond Loretto

NEW ECONOMIC PARADIGMS
The Challenges and Joys of the New Philanthropist: A Hands-on Approach to
International Aid
Philip Berber, A Glimmer of Hope
Community Exchange Systems in the Global South: Appropriate Economics for
Rural Development in the Third World
Stephen DeMeulenaere, Community Exchange Systems, Bali, Indonesia
The Gift Economy: An Economic Framework for the Economy of Communion?
Richard Nelson, Solar Roof Gardens
Sustainable Economic Development Planning Framework
Christopher Juniper, Catamount Institute
The E+Co Approach: Energy Though Enterprise
Gina Rodolico, E+Co, Bloomfield, NJ
Capitalism With Cooperative Sails
Louis Mitchell, Pact Inc., Alexandria, VA
The Role of the Non-Profit in Creating Prototypes for Global Health Care
Using Local Resources
Cyndi Kennedy, All Together Now International, Boulder, CO
The MacroEconomics of Sustainable Development: Is it Possible to Increase
Economic Growth and Eliminate Poverty Without Harming the Environment?
James Bernard Quilligan, Director, Brandt 21 Forum

PRACTICAL POWER
Chasing the Sun Around the World
Neville Williams, Founder and CEO of Solar Electric Light Company,
Gaithersburg, MD
The Solar Entrepreneurs Handbook
Geoffrey Stapleton, Global Sustainable Energy Solutions, Ulladulla,
Australia
Biogas Plants for Farms and Slaughterhouses
Anna Ingwe

REAL WORLD SOLUTIONS
Water Project in Nasik, India
Vinod Parekh, Director of Projects, Village Earth, Fort Collins, CO
Characterization of Power System Loads in Rural Uganda
Frances Sprei, Lund University, Sweden
Renewable Energy in Action: Snapshots from Nepal
Joe Wenisch, University of Colorado, Boulder
Clean Energy: The Challenges and Opportunities in Brazil
Fernando Tibechrani Salgado, ATITUDE- Despertando a A??o Sustent?vel, Brazil
A Successful Microcredit and Community Development Program in Pune, India
Abdul Salam and Jon Schulz
Technology for Human Development: Sustainable Management of Geothermal
Resources in South Peru
Giacomo Bertoldi, University of Trento, Italy
Micro-Hydro Power in Southern India: Problems and Prospects
Anand Narayan, Shyadri Energy System, India
Photovoltaics as a Cottage Industry - Experience in Nicaragua
Richard Komp, Sun Watt Corporation

REINVENTING EDUCATION FOR A SUSTAINABLE WORLD
The Role of Constructivist Education in Achieving Global Sustainability
Spencer Jourdain, Executive Director of the 1420 Foundation
Joint Development of a Master's Program on Sustainability in Europe and Asia
Claes Helgesson, University of Bor?s, Sweden
Afghan-Ed: A project for Restoring Education in Afghanistan
John Beynon, Co-President, The United Nations Association of the USA
Engineers as Agents of Change in Rural Education: Lessons Learned in Nepal
and Myanmar
John Beynon, Co-President, The United Nations Association of the USA
From tmiles at TRMILES.COM Sat Mar 22 14:07:56 2003
From: tmiles at TRMILES.COM (Tom Miles)
Date: Tue Aug 10 18:30:18 2004
Subject: [ethos] Fw: justa pix
Message-ID: <SAT.22.MAR.2003.110756.0800.TMILES@TRMILES.COM>

Ron,

Damon's pictures can now be seen on the Stoves website at both REPP
http://www.repp.org/discussiongroups/resources/stoves/

and on my backup site: http://www/trmiles.com/stoves

Tom
----- Original Message -----
From: "Ron Larson" <ronallarson@qwest.net>
Sent: Saturday, March 22, 2003 10:19 AM

> To all members of "Ethos" and "stoves":
>
> Apologies for asking you to read backwards through 5 messages. Working
> from bottom to top we have:
>
> 4. >>>> Thursday message from Dean Still to the "Ethos" list showing 2
> photos of a stove that I found very beautiful.
>
> 3. >>> My off-line response to Dean, same day, asking 6 questions.
>
> 2. >> Response off-line back yesterday from Damon Ogle answering these
> questions very fully (this is the part of most importance to all stove
> designers, I think).
>
> 1. > My asking yesterday for permission to post our off-line
communication
> and asking a bit more.
>
> 0a. (no ">") Yesterday from Damon (also got Ok from Dean) encouraging a
> post and some more answers.
>
> 0b. I have since been assured by Tom Miles: "They are quite good
pictures.
> I'll see if I can get them up this morning."
>
> 0c. The members of "Ethos" today have also heard a comment from Doug
> McCorkle [mccdo@iastate.edu] on this exchange, saying:
>
> "In response to the discussion about a more evened surface
temperature
> on
> the justa I was wondering if you would be interested in the work that we
> have
> done in the Bryden lab? We have the ability to optimize the baffle
placement
> in a plancha style stove. Also, we have already completed many runs of
this
> algorithm and have suggestions for baffle placement in a plancha that is
> approx. 21" x 21". If anyone would be interested in this information feel
> free
> to contact me and I can send specific dimensions and placement locations
for
> baffles. Also, if the above size plancha is not what is being discussed
> below
> please send me the dimensions and location of the rocket elbow and chimney
> and
> I will try to run it through our algorithm. I can't promise a lightning
fast
> response but I should be able to get an answer for future work."
>
> I hope Doug will keep both "Ethos" and "Stoves" informed on his
> computations of the optimum baffles. I gather than none was used on the 2
> stoves whose photos we have seen. I would also appreciate hearing from
> Doug, Damon, Dean, Mike Hatfield, Don O'Neil, Stewart Conway or anyone
else
> on the possible advantages and the construction techniques for using an
> alternative "inverted funnel" design to try to achieve uniformity.
>
> But I am not at all sure that users in this area would want surface
> uniformity - and hope all can address that issue as well.
>
> To summarize, the things I find most interesting about these stoves are:
>
> 1. very attractive finished product - and done at least in this case by
the
> homeowner. The total cost is not yet clear - but the main $60 (subsidized
> sometimes down to $30) seems very reasonable. I am anxious to hear more
> from everyone on the importance of adding extra costs to improve the
> appearance. I wonder if others think this is a very handsome stove - and
> better than most we see for sale of modern design at 10 times the likely
> price? We all know appearance is important - but how do we accomplish
this
> at acceptable cost? Is homeowner finishing (and starting) the right way?
>
> 2. This dialog enables us to talk more about both what users want in
> surface temperature uniformity and how to achieve it.
>
> 3. Recent talk about energy efficiency computations. This stove doesn't
> lend itself to the ongoing discussions on "stoves" about measuring
> efficiency (and whether pots should or should not be lidded during
testing).
> How should we be measuring these stoves?
>
> Thanks to Dean, Damon, Doug and Tom for much useful information.
>
> Ron
>
>
> -----Original Message-----
> From: Damon Ogle [mailto:monogle@oregoncoast.com]
> Sent: Friday, March 21, 2003 8:21 PM
> To: Ron Larson
> Subject: Re: [ethos] Fw: justa pix
>
>
> Ron,
> Feel free to post wherever you think it might be useful. Edit as you
> see fit.
> Mike Hatfield at Apro might have some more info on cost of platform. Re:
> inverted
> pyramid under griddle surface --Don gave me good drawings and temperature
> gradients
> on the back of a napkin in Seattle. I kept it, but can't find it.
Probably
> best to
> contact Don directly. Re: baffeling -- I don't remember any baffling
under
> the
> planchas. I took some pictures and will look thru them to make sure.
They
> used a
> 24"x24" 1/8" mild steel sheet bent down 1" along ech edge and welded to
give
> a
> 22"x22"plancha. We are recommending changing to a more rectangular shape
> for better
> heat transfer and possibly fewer warping problems.
>
> Damon
>
> Ron Larson wrote:
>
> > Damon (cc Dean) - Thanks for this great reply.
> >
> > I really think that this response would be of great interest to
> the full
> > Ethos group (and also to Stoves). Not sure of the proper etiquette for
> > doing that - but must start with Damon's OK.
> > If OK - I'd still like to know more about:
> > 1. the cost of adding the tiles - even if a guess separately
for
> the
> > tiles and labor. I am just terribly impressed about how high-quality
this
> > now looks. Thansk very much for the very complete costing. (and maybe
> need
> > more on the cost of the platform)
> > 2. Something about the out-of-sight baffling.
> > 3. More on Don O'Neil's inverted pyramid approach and how
uniform
> he can
> > get - and whether it would be wanted - and if we know enough to give the
> > owner whatever she wants.
> > 4. More on AHDESA.
> >
> > I'm willing to do the work of editing - if that would be helpful. If
also
> > "stoves" seems appropriate, we need also to get Tom Miles to put your
two
> > pictures in his picture file.
> >
> > Again - nice work and nice response.
> >
> > Ron
> >
> > >-----Original Message-----
> > >From: Damon Ogle [mailto:monogle@oregoncoast.com]
> > >Sent: Friday, March 21, 2003 5:11 PM
> > >To: Ron Larson; Dean Still
> > >Subject: Re: [ethos] Fw: justa pix
> > >
> > >
> > >Hi Ron, Damon here.
> > >Let me take a stab at answering your questions.
> > > 1. These stoves are part of an AHDESA stove project near
> > >Tegucigalpa. Total cost
> > >of basic stove is about $60. This breaks down to $10.50 for the
> > >plancha (griddle),
> > >$7.58 for the elbow (pottery now, but our new baldosa elbows
> > >should be less then $1),
> > >$4.37 for chimney, $14.55 for skilled labor (the mason/stove
> > >technician), $15 for
> > >transport (and maybe some overhead?) , and $8 for training and
> > >inspection (very
> > >important). The family must also build a suitable platform for
> > >the stove and provide
> > >some basic materials and unskilled labor for the mason. Rotary is
> > >involved in some
> > >projects and I think they and Ahdesa subsidise about half of the
> > >cost of the basic
> > >stove. Bells and whistles (in this case tiles) are paid for by
> > >the stove owners. In
> > >this case the tortilla lady's husband did the tile work on his own.
> > > 2. The technicos (stove masons) are able to do about two
> > >stoves a day and they have
> > >4 or 5 techincos working now. I'm not sure of total numbers but I
> > >think two or three
> > >thousand have been built in neighborhoods around Tegucigalpa in
> > >the last couple of
> > >years.
> > > 3. No hard numbers on wood savings, but the lady whose stove
> > >is pictured claims
> > >that her wood costs went from 280 limpiras per day down to 30 or
> > >40 per day after she
> > >installed the stoves, (I think there are about 8 limpiras to the
> > >dollar). She has three
> > >stoves (only the first of which was subsidized) and about 6 women
> > >are employed making
> > >tortillas for the market, so the stoves are burning all day long.
> > >Most house wives
> > >(cooking for meals only)will tell you that they use 1/3 of the
> > >fuel they used before.
> > >These are probably WAGs but I believe the savings are at least 50%.
> > > 4. There is a hot spot , but the entire surface seems to
> > >remain hot enough to cook
> > >tortillas. They have learned to juggle the tortillas so that they
> > >don't burn.
> > > 5. The top of the rocket elbow is about 2" below the bottom of
> > >the plancha. The
> > >insulation is wood ash and when installed is beveled up to about
> > >1" below the plancha
> > >for most of the path. Ash tends to settle and in most of the
> > >older stoves we inspected
> > >the gap was greater we wanted to see. Maintaining the proper gap
> > >is a problem for
> > >which we have not yet found a good solution.
> > > 6.Don O'Neil uses a version of the inverted pyramid in his
> > >Helps Stove in
> > >guatemala. The side of the elbow toward the chimney is about 2"
> > >lower than the rest of
> > >the elbow sides and a gradual "ramp" slopes up to a 1" gap below
> > >the plancha at a point
> > >about 2/3 of the way to end of the plancha. He uses pumice for
> > >insulation and gets a
> > >much better heat distribution using this configuration.
> > >
> > >A couple of other observations.
> > > This is hard to quantify, but the quality of life goes way up
> > >for people using the
> > >"justas". Before the stove is installed, the kitchens tend to be
> > >dark, and grimey with
> > >lots of sooty cobwebs everywhere. Everything including the cook
> > >and her clothing are
> > >sooty and smell of smoke. After the stoves are installed, the
> > >cooking areas ted to get
> > >cleaned and painted and both clothing and attitudes tend to be
brighter.
> > > I don't know about CO emmisions, but visually the stoves seem
> > >to burn very clean.
> > >When you look at the chimney from outside the house it is almost
> > >impossible to tell
> > >whether the stove is burning or not. If you look very closely you
> > >can see the heat
> > >waves.
> > > These are very good stoves, but the target group seems to be a
> > >somewhat middle
> > >class family (by C.A.standands). I certainly think we should
> > >continue to build as many
> > >"justas" as possible, but we should also try to target the poorer
> > >part of the
> > >population by developing a much cheaper simple stove for people
> > >who will never be able
> > >to afford a $60 stove.
> > > Lets do both.
> > >
> > > Damon
> > >
> > >
> > >Ron Larson wrote:
> > >
> > >> Dean:
> > >>
> > >> Thanks for the two pictures of the "Fancy Justa" (and a
> > >reminder about your
> > >> grandmother and Quakers).
> > >>
> > >> I too was impressed by the beauty of the stoves. The
> > >ceramic tiles are
> > >> wonderful looking. Several questions (maybe for Damon?):
> > >>
> > >> 1. What is the cost of these units - and what
> > >proportion of the cost is in
> > >> making the stove a work of art?
> > >>
> > >> 2. What is the method of production? All knowledge
> > >transferred to local
> > >> artisans and in full scale production? How many out there like
> > >these two?
> > >>
> > >> 3. Any way to talk about efficiency - or
> > >wood-consumption in comparison to
> > >> the stoves they are replacing?
> > >>
> > >> 4. It seems in Picture #1 that there might be a hot
> > >spot that is being
> > >> avoided. Is this usually used for a pot - or would the users
> > >prefer a more
> > >> uniform surface temperature? It looks like maybe the tortillas
(right
> > >> word?) are moved closer to the (presumably cooler) exit pipe as they
> are
> > >> finishing cooking - is a varying surface temperature maybe considered
> an
> > >> asset by the cooks?
> > >>
> > >> 5. What sort of flame path is underneath and out of
> > >sight? (What sort of
> > >> baffling?)
> > >>
> > >> 6. Have the developers ever tried using an inverted
> > >pyramid for the flame
> > >> path - in an attempt to get greater surface temperature uniformity?
(I
> > >> don't think that the Ethiopian enjira could be cooked on this
> > >surface - as
> > >> the typical diameter is about 60 cm.
> > >>
> > >> Thanks in advance for any answers - and thanks for sharing the
> pictures.
> > >>
> > >> Ron
> > >>
> > >> >-----Original Message-----
> > >> >From: owner-ethos@vrac.iastate.edu
> > >> >[mailto:owner-ethos@vrac.iastate.edu]On Behalf Of Dean Still
> > >> >Sent: Thursday, March 20, 2003 4:53 PM
> > >> >To: ethos
> > >> >Subject: [ethos] Fw: justa pix
> > >> >
> > >> >
> > >> >Really nice Justa stoves. I want one! Pictures taken by Damon
Ogle...
> > >> >
> > >> >Best,
> > >> >
> > >> >Dean
> > >> >
> > >> >PS: My grandmother, who died at the age of 102, lived through many
> > >> >wars. She
> > >> >once told the grandkids that everytime there was a war in her
> > >country she
> > >> >gathered all the family together and they did a very thorough Spring
> > >> >cleaning. After the First World War she became a Quaker because
> > >as soon as
> > >> >the fighting stopped Quakers from England brought food to the
starving
> > >> >Germans.
> > >> >
> > >> >Subject: justa pix
> > >> >
> > >> >
> > >> >
> > >
> > >
> > >
> > >
>
>
>
>
>

From ronallarson at QWEST.NET Sat Mar 22 16:16:05 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: FW: SR 2003 (more on a conference venue)
Message-ID: <SAT.22.MAR.2003.141605.0700.RONALLARSON@QWEST.NET>

Stovers:

This as a follow-up to my last message. What guidance can I get as I talk
more with the conference organizers? We alread have some good presenters -
but need a few more.

Ron

-----Original Message-----
From: Steve Troy [mailto:steve@sustainablevillage.com]
Sent: Saturday, March 22, 2003 12:51 PM
To: Ron Larson
Subject: RE: SR 2003

Ron,
A new development: we're planning to start on Monday instead of
Wednesday night with seminars. NREL is doing a 2-day one on renewable
energy, RMI on natural capitalism, Naropa on leadership. Possibly the
stove group could fit into this schedule. That way you could have
more time without having to miss the other workshops. It also could
make a long trip here more worthwhile.
Steve
--

===============================================================
The Sustainable Village, LLC 717 Poplar Ave.
Boulder, CO 80304
email: steve@sustainablevillage.com web site:
www.sustainablevillage.com
voice 303-998-1323 ext. 100, 888-317-1600 fax
303-449-1348
Sustainable Resources 2003
<www.carebridge.info/sr2003/index.html>
"Resources for the Developing
World"

From crispin at NEWDAWN.SZ Sat Mar 22 15:58:54 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:18 2004
Subject: Value of secondary air - is there a way to show it
Message-ID: <SAT.22.MAR.2003.225854.0200.CRISPIN@NEWDAWN.SZ>

Dear Dean

This is the best I can relate:

He measured the efficiency of heat utilization by calculating the amount of
heat present in the lousy coal he is gasifying (28 MJ/Kg with something like
27% volatiles). He found that 19% of that heat got into the pot with that
particular configuration. That is, heated water, nothing calculated for the
steel pot.

Then he added a shroud around the outside of the stove so that the secondary
air, which enters the stove through a controller, was heated by heat
escaping through the outside wall of the stove. This undoubtedly raised the
temperature of the stove wall and will have affected combustion in that way,
however it was the heating of the secondary air that he was achieving.

With the heated secondary air, the % of heat getting from the coal into the
pot increased to 25%.

As it is probably unlikely that one can remove the influence on the stove
body of a shroud, it is likely that the only way to further refine this
experiment is to separately heat the secondary air with other fuel and then
pipe it into the stove.

However the disadvantage of that is it is not recycling heat but adding new
heat and might be criticised as assisting the fire (cheating).

Not sure what to say beyond that. Adding the secondary air preheating
shroud increased the PHU by about 31% and I believe it was in part due to
better combustion and in part due to having a gas (air) insulated shroud
which drove up internal temperatures. I would conclude that the benefits
are obvious.

Regards
Crispin

Dear Crispin,

I don't understand whether you mean an increase in the system efficiency SE
of the stove ( % of energy in wood gotten into the pot) or an increase in
the actual heat transfer to the pot ? The simple WBT and the like don't tell
us about combustion efficiency CE or heat transfer efficiency HTE but we get
a number which is the two multiplied together which is system efficiency SE.
Was Davies reporting a rise in SE by improving CE?

All Best,

Dean

From tmiles at TRMILES.COM Sat Mar 22 18:12:13 2003
From: tmiles at TRMILES.COM (Tom Miles)
Date: Tue Aug 10 18:30:18 2004
Subject: New Website Additions
Message-ID: <SAT.22.MAR.2003.181213.0500.TMILES@TRMILES.COM>

Several new contributions have been added to the stoves website in the
past few weeks. Stovers have been very active.
1. We received an excellent publication on a Beehive Charcoal Briquette
Stove from Sjoerd Nienhuys, SNV (Netherlands Development Organization)
Nepal
2. Damon Ogle provided pictures of a fancy Justa stove.
2. Jim Wilmes provides visual instructions for building the Justa stove.
3. Dean still provides a slide show for making insulative clay
(vermiculite-clay) combustion chambers.
4. Lanny Henson gives us the benefit of his Rice Cooking Trials
5. Tami Bond has put up a Web Page including her emissions testing and
ETHOS presentations

http://www.repp.org/discussiongroups/resources/stoves/

Tom Miles

From ronallarson at QWEST.NET Sat Mar 22 19:13:27 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: Forwarding Damon on TWP and tiling
Message-ID: <SAT.22.MAR.2003.171327.0700.RONALLARSON@QWEST.NET>

Stovers:

Below Damon is giving well deserved credit to Stuart Conway and Trees Water
people (TWP). I wish we would hear more about and from Stuart - as his
non-profit has been doing some great stoves work - mostly but not entirely
in Central America. I have been in his (old, not yet his new) office and
thought he had half of the city's retired working as volunteers sending out
his newsletter. See more at http://www.treeswaterpeople.org/.

-----Original Message-----
From: Damon Ogle [mailto:monogle@oregoncoast.com]
Sent: Saturday, March 22, 2003 4:18 PM
To: Ron Larson
Subject: Re: [ethos] Fw: justa pix

Ron,
A couple of things I neglected to mention before.
Trees Water People , based in Fort Collins, Colorado runs stove projects
in
several countries, including Honduras, El Salvador and Guatemala. AHDESA is
their
local partner in Honduras. In El Salvador and Guatemala , they work with
other
organizations. Our work in all three countries was made possible by Stuart
Conway
and his organization TWP.
The stove pictured is only one of several stoves in the area which had
been tiled
or improved in other ways. I don't know how much the tiling cost, but I
sespect it
was minimal as ceramics are very inexpensive in the area. Dean has a cd
with
pictures of other stoves in and around Tegucigalpa which have been
embellished in
different ways. People are proud of their stoves and want to show them
off..

From ronallarson at QWEST.NET Sun Mar 23 02:05:09 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:18 2004
Subject: Beehive report
In-Reply-To: <NGBBKDEHILILFNJPHEFIGEHMCKAA.ronallarson@qwest.net>
Message-ID: <SUN.23.MAR.2003.000509.0700.RONALLARSON@QWEST.NET>

Sjoerd (cc Stovers):

This is mainly to follow up on my note of March 19 on your very interesting
stoves work in Nepal (citation given again today by Tom Miles) with some
questions:

1. It appears that your paper was designed to set down all of the good and
bad aspects of the various stoves you are now considering for high altitudes
in Nepal. You have done a nice job in doing this - but it appears that you
are still not quite settled on a choice - and are perhaps looking for
comments. Is this correct? We have few discussions of stoves for heating
and this is a good application for further discussion.

2. Assuming this is so, I've got a few questions and comments below.

3. You first (up to p 8, through section 2.1) talk about the Nepalese
"beehive", which for those haven't read your material yet seems to be
moderately successful - but with problems especially in the briquette
manufacture.
The part I found most interesting here was in the "charring process" figure
on p4. This method is similar to the "downdraft method" developed by Elsen
Karstad in Nairobi for sawdust, bagasse, and similar material. This is to
ask Elsen to comment. Both of you are adding material and the pyrolysis
front is moving upward. One difference is that yours requires a final
period in which the material just "cooks". I think others like the Karves
should look at this design for a possibly useful approach in their
production of charcoal also from ag residues (and you should look at
theirs).
My own interest has been in producing charcoal while cooking - but don't
think I could use your raw materials. But I do hope you will look at ways
to make charcoal and simultaneously use the large amount of potentially
useful heat flared in your pyrolysis gases.

4. Next in Section 2.2 (pp 9-10) you introduce a somewhat similar stove
from Tibet - that you obviously prefer - and so will most on this list.
Charcoal burning is relatively new to our list - with the nearest equivalent
being the stove being developed by the Karves in Pune. I hope you and they
will share experiences - as their introduction seems to be going very well.
Your figure on p 10 reminds me that you might consider preheating of your
air supply - by moving the air supply hole up to the top of the stove, with
the air then picking up temperature as it traverses down to the bottom of
the briquettes. This is the crux of much of the "stoves" dialog on
preheating still going on - being led by Crispin.
But Crispin (and some others of us) are interested in separating primary
and secondary air and controlling both when the fuel is biomass. It appears
that with a charcoal-burning stove there may be a need only for the primary
air and I hope others will jump in on whether that is true. Anyone know of
any successful charcoal burning stoves where the secondary air component is
critical?

5. Your section 3 gives some background for making a stoves choice and is
very nice. I have not seen a figure like that on p 12 (giving annual fuel
consumption as a function of altitude for a family of 5). Your low figure
below 1000 m altitude gives about 8 kg per day which seems high - what is
the origin of this figure?
The right hand part of that figue shows some sort of biomass production as
a function of altitude - but I need help with the units. I hope Ray
Wijewardene (Sri Lanka) and A.D Karve (Pune) will throw in some ideas on how
to most efficiently supply biomass on a plantation basis (I think they will
promote bamboo).

6. Section 3.3 (pp 13-15) is very helpful - and I recommend it to others
especially on making charcoal briquettes. I don't know enough to ask an
intelligent question here - but I like your observation that the 19 holes
gives a superior flame. Anything more on this subject would be appreciated.
Any pictures of flames?

7. Section 4 brings in three other stoves types:

a. The Rocket on p 16. Obviously you know this well - but I hope Larry,
Dean and others will look over your comments and offer their comments. They
have recently been doing a lot with low mass insulating ceramic/brick walls
that you don't mention.

b. The Satellite stove - p 17 I like all the improvements you show. You
are getting close here to the work of Lanny Henson - who has a somewhat
similar design but with a chimney and a method of achieving "swirl" to lower
the overall profile. It would seem that a chimney might be a pretty useful
addition in high-altitude Nepal - and would avoid the necessity of outdoor
lighting.

c. The Paru stove (p 18) was new to me by this name - but the name of Dr.
Grover has been mentioned several times in the past with almost this same
design (I saw two much larger versions in Zimbabwe in 1995 attributed to
Grover). I understood that the power control was not good and wonder if
that is still true. "Stoves" list member Auke Koopmans was listed as the
author of this report and I hope he will tell us if this Paru stove ever
reached a commercial stage?
I tried to find the cited reference through REPP - but found the paper
missing (Tom Miles take note). But I eventually found it at
http://www.rwedp.org/acrobat/rm56.pdf
The description called for the addition of a few small pebbles which stay
red hot - and I have not previously seen this listed. Anyone with
experience on this?

I hope that we can hear more about this stove from you or others familiar
with it. It appears that it is designed to produce char (with full waste
heatr utilization) and I am all in favor of that. I believe that a similar
design with an air port at the top to allow controllable primary air and
downdraft might be a distinct improvement (as power level could be
controlled - and would be sort of an inverse of what I have been working
on). The claims in this report about clean operation are ones some of us
have been making and I hope that you or Auke can report if there have been
any emissions measurements on this Grover stove.

8. The final page is a very nice summary (the best I know of) from a 1994
World Bank report by Kirk Smith and others (I found a copy at Kirk's web
site as: http://ehs.sph.berkeley.edu/krsmith/Publications/WB_Report.pdf
Everyone on "stoves" should look at this list, which I reproduce in poor
form below (poor as Sjoerd has made bold all those items that are pertinent
to his need in Nepal looking at a charcoal briquette burner).

9. that concludes my thoughts on your paper. Here are a few small
questions that will help me/others better understand what is happening in
Nepal:

a. You used a conversion factor between the Nepalese rupee and the Euro of
80 to one. What is the "minimum" or average wage in your areas of Nepal?

b. Given the very high transportation costs and shortage of biomass
materials, it would seem that solar cookers might be a good alternative for
both natives and trekkers - at least for when the weather was good. What is
the history of any such intervention? Can you tell us more about the
typical meal? One burner enough? etc

c. Others on "stoves" have considered binders like the 30% clay-soil which
you didn't like. Elsen Karstad (Nairobi) uses about 15% and the Karves
(Pune India) use only waste flour. Can you report on any tests showing the
results of variations in clay content?

d. With your numbers for 6 MJ per briquette and 1 hour duration, you are
operating at about 1.6 kW. Do you now have any control over that in the
small system? (airflow control?) How much in the Tibet version?

e. You talk about particulate emission also on p5. How are you measuring
this? Better or worse than other types of charcoal stoves? Tami Bond has
done a lot of work on particulate emission from holey coal briquettes and I
hope she will look at your results. Any chance of getting some sent to her
or others?

f. On page 7 you show some air control regulators, but none for the unit
on p 5. Is there good or only fair control for the 8-briquette unit? Can
you estimate the Turndown ratio (ratio of max to min combustion times)?

Again thank you for supplying this very comprehensive report. We need more
such thorough documentation.
I think the Dutch development programs are some of the best and yours is a
good example. I hope your report will stir some dialog and that my review
will help you and others to compare and develop new ideas - as there are
several new areas for us in what you are doing - which I hope I have noted
above.

Ron

End of RWL comments.

The remainder is the nice check list coming from Sjoerd's last page and
earlier from the Word Bank paper 242. Note the second list is sort of the
reverse of the first. See Sjoerd's paper for what is bold. The full WB
paper (60pp) goes into greater detail on many of the criteria.

I wonder if anyone objects to anything on this list or can add any more?
For example, my comments in a different message today about beauty in a
stove - I don't see on this list.

Box 4. Possible Reasons for Success or Failure
Reasons for success
1. Program targets region where traditional fuel and
stove are purchased or fuel is hard to collect.
2. People cook in environments where smoke
causes health problems and is annoying.
3. Market surveys are undertaken to assess potential
market for improved stoves.
4. Stoves are designed according to consumer
preferences, including testing under actual use.
5. Stoves are designed with assistance from local
artisans.
6. Local or scrap materials are used in production
of the stove, making it relatively inexpensive.
7. The production of the stove by artisans or
manufacturers is not subsidized.
8. Stove or critical components are mass produced.
9. Similar to traditional stove.
10. The stove is easy to light and accepts different-sized
wood.
11. Power output of stove can be adjusted.
12. The government assists only in dissemination,
technical advice, and quality control.
13. The stove saves fuel, time, and effort.
14. Donor or government support extended over at least
5 years and designed to build local institutions and
develop local expertise.
15. Monitoring and evaluation criteria and
responsibilities chosen during planning stages according
to specific goals of project.
16. Consumer payback of 1 to 3 months.

Reasons for failure
1. Program targets region where traditional fuel or
stove are not purchased or fuel is easy to collect.
2. People cook in the open, and smoke is not really
a problem.
3. Outside "experts" determine that improved stoves
are required.
4. Stove is designed as a technical package in the
laboratory, ignoring customers' preferences.
5. Local artisans are told or even contracted to build
stoves according to specifications.
6. Imported materials are used in the production of
the stove, making it expensive.
7. The production of the stove by artisans or
manufacturers is subsidized.
8. Critical stove components are custom built.
9. Dissimilar to traditional stove.
10. The stove is difficult to light and requires the
use of small pieces of wood.
11. Power output cannot be easily controlled.
12. The government is involved in production.
13. The stove does not live up to promised
economy or convenience under real cooking
conditions.
14. Major achievements expected in less than 3
years, all analysis, planning, and management done
by outsiders.
15. Monitoring and evaluation needs are not planned
and budgeted, or criteria are taken uncritically from
other projects or not explicit I y addressed.
16. Consumer payback of more than 1 year.

Ron

>-----Original Message-----
>From: Ron Larson [mailto:ronallarson@qwest.net]
>Sent: Wednesday, March 19, 2003 5:59 PM
>To: Sjoerd Nienhuys; STOVES@LISTSERV.REPP.ORG
>Subject: RE: [STOVES] Beehive report
>
>
>Sjoerd and stovers:
>
> The right reference for this site/cite is
>http://www.repp.org/discussiongroups/resources/stoves/Nienhuys/Beeh
>ive%20Stove.pdf
>
> Tom Miles has done a great job in adding photos and longer
>reports like Sjoerd's.
>
> I haven't read this yet, but note that Sjoerd is using the
>19-hole "holey" briquette design. It looks quite complete, with
>reference to many of the things we talk about. Thanks to Sjoerd
>for getting this to us.
>
>Ron
>
>

<snip>
>>
>>Sjoerd Nienhuys
>>Senior Renewable Energy Advisor
>>SNV/N, Netherlands Development Organisation
>>P.O. Box 1966, Kathmandu, Nepal
>>Telephone: ++997-1-5523444
>>snienhuys@snv.org.np
>>
>>

From rmiranda at INET.COM.BR Sun Mar 23 21:22:22 2003
From: rmiranda at INET.COM.BR (Rogerio Carneiro de Miranda)
Date: Tue Aug 10 18:30:19 2004
Subject: justa pix
In-Reply-To: <NGBBKDEHILILFNJPHEFICEKKCKAA.ronallarson@qwest.net>
Message-ID: <SUN.23.MAR.2003.232222.0300.RMIRANDA@INET.COM.BR>

Ron and all:

Regarding evened surface temperatures in the justa stove, it could be
nearly achieved or improved with the inverted pyramid (it was done in
Honduras by PROLE?A), however it only could be helpful to tortillas makers,
but they still need at least 200 celsius to cook the tortillas.

For home cooking, the concentrated hotter spot is welcome, used for faster
cooking, and once boiling is achieved, the pot is then moved to lower
temperatures areas of the griddle, to continue boiling and cooking.

Regarding the baffle placement, I suggest to DougMcCorkle to try our
latest version of the Ecostove in Nicaragua. It uses the same traditional
griddle of 22 x 22 inches, however with the rocket located at front right
corner of the griddle and distant 7 inches and 6 inches from the
closest border. The chimney outlet is located in the opposite right back
side of the griddle. Between the chimney and the rocket burner there is a L
shaped baffle which force the hot gases to circulate under the griddle
before reaching the chimney outlet, increasing the residence time of the
gases under the griddle, transferring as much heat as possible. This for
us, is the most effective way to absorb heat from the rocket stove.

Please try this design as your baseline, and try to improve it. The best
design in my opinion for justa-ecostove models, would be the one that can
provide a really hot spot for quick cooking, and other not so hot, but
still hot as much possible for follow up cooking.

This model is greatly appreciate by cookers,since it can prepare the lunch
meal faster than open fires, when cooking simultaneously 3 to 4 pots.

Rogerio

At 11:19 a.m. 22/03/03 -0700, Ron Larson wrote:
>To all members of "Ethos" and "stoves":
>
> Apologies for asking you to read backwards through 5
> messages. Working
>from bottom to top we have:
>
>4. >>>> Thursday message from Dean Still to the "Ethos" list showing 2
>photos of a stove that I found very beautiful.
>
>3. >>> My off-line response to Dean, same day, asking 6 questions.
>
>2. >> Response off-line back yesterday from Damon Ogle answering these
>questions very fully (this is the part of most importance to all stove
>designers, I think).
>
>1. > My asking yesterday for permission to post our off-line communication
>and asking a bit more.
>
>0a. (no ">") Yesterday from Damon (also got Ok from Dean) encouraging a
>post and some more answers.
>
>0b. I have since been assured by Tom Miles: "They are quite good
>pictures.
>I'll see if I can get them up this morning."
>
>0c. The members of "Ethos" today have also heard a comment from Doug
>McCorkle [mccdo@iastate.edu] on this exchange, saying:
>
> "In response to the discussion about a more evened surface temperature
>on
>the justa I was wondering if you would be interested in the work that we
>have
>done in the Bryden lab? We have the ability to optimize the baffle placement
>in a plancha style stove. Also, we have already completed many runs of this
>algorithm and have suggestions for baffle placement in a plancha that is
>approx. 21" x 21". If anyone would be interested in this information feel
>free
>to contact me and I can send specific dimensions and placement locations for
>baffles. Also, if the above size plancha is not what is being discussed
>below
>please send me the dimensions and location of the rocket elbow and chimney
>and
>I will try to run it through our algorithm. I can't promise a lightning fast
>response but I should be able to get an answer for future work."
>
> I hope Doug will keep both "Ethos" and "Stoves" informed on his
>computations of the optimum baffles. I gather than none was used on the 2
>stoves whose photos we have seen. I would also appreciate hearing from
>Doug, Damon, Dean, Mike Hatfield, Don O'Neil, Stewart Conway or anyone else
>on the possible advantages and the construction techniques for using an
>alternative "inverted funnel" design to try to achieve uniformity.
>
> But I am not at all sure that users in this area would want surface
>uniformity - and hope all can address that issue as well.
>
> To summarize, the things I find most interesting about these
> stoves are:
>
>1. very attractive finished product - and done at least in this case by the
>homeowner. The total cost is not yet clear - but the main $60 (subsidized
>sometimes down to $30) seems very reasonable. I am anxious to hear more
>from everyone on the importance of adding extra costs to improve the
>appearance. I wonder if others think this is a very handsome stove - and
>better than most we see for sale of modern design at 10 times the likely
>price? We all know appearance is important - but how do we accomplish this
>at acceptable cost? Is homeowner finishing (and starting) the right way?
>
>2. This dialog enables us to talk more about both what users want in
>surface temperature uniformity and how to achieve it.
>
>3. Recent talk about energy efficiency computations. This stove doesn't
>lend itself to the ongoing discussions on "stoves" about measuring
>efficiency (and whether pots should or should not be lidded during testing).
>How should we be measuring these stoves?
>
> Thanks to Dean, Damon, Doug and Tom for much useful information.
>
>Ron
>
>
>-----Original Message-----
>From: Damon Ogle [mailto:monogle@oregoncoast.com]
>Sent: Friday, March 21, 2003 8:21 PM
>To: Ron Larson
>Subject: Re: [ethos] Fw: justa pix
>
>
>Ron,
> Feel free to post wherever you think it might be useful. Edit as you
>see fit.
>Mike Hatfield at Apro might have some more info on cost of platform. Re:
>inverted
>pyramid under griddle surface --Don gave me good drawings and temperature
>gradients
>on the back of a napkin in Seattle. I kept it, but can't find it. Probably
>best to
>contact Don directly. Re: baffeling -- I don't remember any baffling under
>the
>planchas. I took some pictures and will look thru them to make sure. They
>used a
>24"x24" 1/8" mild steel sheet bent down 1" along ech edge and welded to give
>a
>22"x22"plancha. We are recommending changing to a more rectangular shape
>for better
>heat transfer and possibly fewer warping problems.
>
> Damon
>
>Ron Larson wrote:
>
> > Damon (cc Dean) - Thanks for this great reply.
> >
> > I really think that this response would be of great interest to
>the full
> > Ethos group (and also to Stoves). Not sure of the proper etiquette for
> > doing that - but must start with Damon's OK.
> > If OK - I'd still like to know more about:
> > 1. the cost of adding the tiles - even if a guess separately for
>the
> > tiles and labor. I am just terribly impressed about how high-quality this
> > now looks. Thansk very much for the very complete costing. (and maybe
>need
> > more on the cost of the platform)
> > 2. Something about the out-of-sight baffling.
> > 3. More on Don O'Neil's inverted pyramid approach and how uniform
>he can
> > get - and whether it would be wanted - and if we know enough to give the
> > owner whatever she wants.
> > 4. More on AHDESA.
> >
> > I'm willing to do the work of editing - if that would be helpful. If also
> > "stoves" seems appropriate, we need also to get Tom Miles to put your two
> > pictures in his picture file.
> >
> > Again - nice work and nice response.
> >
> > Ron
> >
> > >-----Original Message-----
> > >From: Damon Ogle [mailto:monogle@oregoncoast.com]
> > >Sent: Friday, March 21, 2003 5:11 PM
> > >To: Ron Larson; Dean Still
> > >Subject: Re: [ethos] Fw: justa pix
> > >
> > >
> > >Hi Ron, Damon here.
> > >Let me take a stab at answering your questions.
> > > 1. These stoves are part of an AHDESA stove project near
> > >Tegucigalpa. Total cost
> > >of basic stove is about $60. This breaks down to $10.50 for the
> > >plancha (griddle),
> > >$7.58 for the elbow (pottery now, but our new baldosa elbows
> > >should be less then $1),
> > >$4.37 for chimney, $14.55 for skilled labor (the mason/stove
> > >technician), $15 for
> > >transport (and maybe some overhead?) , and $8 for training and
> > >inspection (very
> > >important). The family must also build a suitable platform for
> > >the stove and provide
> > >some basic materials and unskilled labor for the mason. Rotary is
> > >involved in some
> > >projects and I think they and Ahdesa subsidise about half of the
> > >cost of the basic
> > >stove. Bells and whistles (in this case tiles) are paid for by
> > >the stove owners. In
> > >this case the tortilla lady's husband did the tile work on his own.
> > > 2. The technicos (stove masons) are able to do about two
> > >stoves a day and they have
> > >4 or 5 techincos working now. I'm not sure of total numbers but I
> > >think two or three
> > >thousand have been built in neighborhoods around Tegucigalpa in
> > >the last couple of
> > >years.
> > > 3. No hard numbers on wood savings, but the lady whose stove
> > >is pictured claims
> > >that her wood costs went from 280 limpiras per day down to 30 or
> > >40 per day after she
> > >installed the stoves, (I think there are about 8 limpiras to the
> > >dollar). She has three
> > >stoves (only the first of which was subsidized) and about 6 women
> > >are employed making
> > >tortillas for the market, so the stoves are burning all day long.
> > >Most house wives
> > >(cooking for meals only)will tell you that they use 1/3 of the
> > >fuel they used before.
> > >These are probably WAGs but I believe the savings are at least 50%.
> > > 4. There is a hot spot , but the entire surface seems to
> > >remain hot enough to cook
> > >tortillas. They have learned to juggle the tortillas so that they
> > >don't burn.
> > > 5. The top of the rocket elbow is about 2" below the bottom of
> > >the plancha. The
> > >insulation is wood ash and when installed is beveled up to about
> > >1" below the plancha
> > >for most of the path. Ash tends to settle and in most of the
> > >older stoves we inspected
> > >the gap was greater we wanted to see. Maintaining the proper gap
> > >is a problem for
> > >which we have not yet found a good solution.
> > > 6.Don O'Neil uses a version of the inverted pyramid in his
> > >Helps Stove in
> > >guatemala. The side of the elbow toward the chimney is about 2"
> > >lower than the rest of
> > >the elbow sides and a gradual "ramp" slopes up to a 1" gap below
> > >the plancha at a point
> > >about 2/3 of the way to end of the plancha. He uses pumice for
> > >insulation and gets a
> > >much better heat distribution using this configuration.
> > >
> > >A couple of other observations.
> > > This is hard to quantify, but the quality of life goes way up
> > >for people using the
> > >"justas". Before the stove is installed, the kitchens tend to be
> > >dark, and grimey with
> > >lots of sooty cobwebs everywhere. Everything including the cook
> > >and her clothing are
> > >sooty and smell of smoke. After the stoves are installed, the
> > >cooking areas ted to get
> > >cleaned and painted and both clothing and attitudes tend to be brighter.
> > > I don't know about CO emmisions, but visually the stoves seem
> > >to burn very clean.
> > >When you look at the chimney from outside the house it is almost
> > >impossible to tell
> > >whether the stove is burning or not. If you look very closely you
> > >can see the heat
> > >waves.
> > > These are very good stoves, but the target group seems to be a
> > >somewhat middle
> > >class family (by C.A.standands). I certainly think we should
> > >continue to build as many
> > >"justas" as possible, but we should also try to target the poorer
> > >part of the
> > >population by developing a much cheaper simple stove for people
> > >who will never be able
> > >to afford a $60 stove.
> > > Lets do both.
> > >
> > > Damon
> > >
> > >
> > >Ron Larson wrote:
> > >
> > >> Dean:
> > >>
> > >> Thanks for the two pictures of the "Fancy Justa" (and a
> > >reminder about your
> > >> grandmother and Quakers).
> > >>
> > >> I too was impressed by the beauty of the stoves. The
> > >ceramic tiles are
> > >> wonderful looking. Several questions (maybe for Damon?):
> > >>
> > >> 1. What is the cost of these units - and what
> > >proportion of the cost is in
> > >> making the stove a work of art?
> > >>
> > >> 2. What is the method of production? All knowledge
> > >transferred to local
> > >> artisans and in full scale production? How many out there like
> > >these two?
> > >>
> > >> 3. Any way to talk about efficiency - or
> > >wood-consumption in comparison to
> > >> the stoves they are replacing?
> > >>
> > >> 4. It seems in Picture #1 that there might be a hot
> > >spot that is being
> > >> avoided. Is this usually used for a pot - or would the users
> > >prefer a more
> > >> uniform surface temperature? It looks like maybe the tortillas (right
> > >> word?) are moved closer to the (presumably cooler) exit pipe as they
>are
> > >> finishing cooking - is a varying surface temperature maybe considered
>an
> > >> asset by the cooks?
> > >>
> > >> 5. What sort of flame path is underneath and out of
> > >sight? (What sort of
> > >> baffling?)
> > >>
> > >> 6. Have the developers ever tried using an inverted
> > >pyramid for the flame
> > >> path - in an attempt to get greater surface temperature uniformity? (I
> > >> don't think that the Ethiopian enjira could be cooked on this
> > >surface - as
> > >> the typical diameter is about 60 cm.
> > >>
> > >> Thanks in advance for any answers - and thanks for sharing the
>pictures.
> > >>
> > >> Ron
> > >>
> > >> >-----Original Message-----
> > >> >From: owner-ethos@vrac.iastate.edu
> > >> >[mailto:owner-ethos@vrac.iastate.edu]On Behalf Of Dean Still
> > >> >Sent: Thursday, March 20, 2003 4:53 PM
> > >> >To: ethos
> > >> >Subject: [ethos] Fw: justa pix
> > >> >
> > >> >
> > >> >Really nice Justa stoves. I want one! Pictures taken by Damon Ogle...
> > >> >
> > >> >Best,
> > >> >
> > >> >Dean
> > >> >
> > >> >PS: My grandmother, who died at the age of 102, lived through many
> > >> >wars. She
> > >> >once told the grandkids that everytime there was a war in her
> > >country she
> > >> >gathered all the family together and they did a very thorough Spring
> > >> >cleaning. After the First World War she became a Quaker because
> > >as soon as
> > >> >the fighting stopped Quakers from England brought food to the starving
> > >> >Germans.
> > >> >
> > >> >Subject: justa pix
> > >> >
> > >> >
> > >> >
> > >
> > >
> > >
> > >

From elk at WANANCHI.COM Sun Mar 23 09:40:58 2003
From: elk at WANANCHI.COM (elk)
Date: Tue Aug 10 18:30:19 2004
Subject: Beehive report
Message-ID: <SUN.23.MAR.2003.174058.0300.ELK@WANANCHI.COM>

Ron;

W. ref our briquetting, we do not use clay these days- it increases ash
content to unacceptable levels- at least for the local market, which uses
lump wood charcoal as the market standard.

VWB, - vendor's waste briquettes- do have over 25% ash from tramp mud & clay
that finds its way into the waste material at the vendor's site. That's our
only binder...... we add nothing else- just mill, mix in water, extrude and
dry.

For our other charcoal briquettes- made from carbonised bagasse, sawdust,
coffee parchment etc.- we use what's available locally & is most cost
efficient; molasses, gum arabic & starch are our current favourites.

I couldn't download Sjoerd's Beehive Report. My internet connection is
particularly poor at the moment. I'm interested to read about the charring
process. Could you cut & past the relevant section into an e-mail for me
(and other stover's who are connectively challenged.

Thanks;
elk

--------------------------
Elsen L. Karstad
elk@wananchi.com
www.chardust.com
Nairobi Kenya

----- Original Message -----
From: "Ron Larson" <ronallarson@QWEST.NET>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Sunday, March 23, 2003 10:05 AM
Subject: Re: [STOVES] Beehive report

> Sjoerd (cc Stovers):
>
>
> This is mainly to follow up on my note of March 19 on your very
interesting
> stoves work in Nepal (citation given again today by Tom Miles) with some
> questions:
>
> 1. It appears that your paper was designed to set down all of the
good and
> bad aspects of the various stoves you are now considering for high
altitudes
> in Nepal. You have done a nice job in doing this - but it appears that
you
> are still not quite settled on a choice - and are perhaps looking for
> comments. Is this correct? We have few discussions of stoves for heating
> and this is a good application for further discussion.
>
> 2. Assuming this is so, I've got a few questions and comments
below.
>
> 3. You first (up to p 8, through section 2.1) talk about the
Nepalese
> "beehive", which for those haven't read your material yet seems to be
> moderately successful - but with problems especially in the briquette
> manufacture.
> The part I found most interesting here was in the "charring
process" figure
> on p4. This method is similar to the "downdraft method" developed by
Elsen
> Karstad in Nairobi for sawdust, bagasse, and similar material. This is to
> ask Elsen to comment. Both of you are adding material and the pyrolysis
> front is moving upward. One difference is that yours requires a final
> period in which the material just "cooks". I think others like the Karves
> should look at this design for a possibly useful approach in their
> production of charcoal also from ag residues (and you should look at
> theirs).
> My own interest has been in producing charcoal while cooking - but
don't
> think I could use your raw materials. But I do hope you will look at ways
> to make charcoal and simultaneously use the large amount of potentially
> useful heat flared in your pyrolysis gases.
>
> 4. Next in Section 2.2 (pp 9-10) you introduce a somewhat similar
stove
> from Tibet - that you obviously prefer - and so will most on this list.
> Charcoal burning is relatively new to our list - with the nearest
equivalent
> being the stove being developed by the Karves in Pune. I hope you and
they
> will share experiences - as their introduction seems to be going very
well.
> Your figure on p 10 reminds me that you might consider preheating
of your
> air supply - by moving the air supply hole up to the top of the stove,
with
> the air then picking up temperature as it traverses down to the bottom of
> the briquettes. This is the crux of much of the "stoves" dialog on
> preheating still going on - being led by Crispin.
> But Crispin (and some others of us) are interested in separating
primary
> and secondary air and controlling both when the fuel is biomass. It
appears
> that with a charcoal-burning stove there may be a need only for the
primary
> air and I hope others will jump in on whether that is true. Anyone know
of
> any successful charcoal burning stoves where the secondary air component
is
> critical?
>
> 5. Your section 3 gives some background for making a stoves
choice and is
> very nice. I have not seen a figure like that on p 12 (giving annual fuel
> consumption as a function of altitude for a family of 5). Your low figure
> below 1000 m altitude gives about 8 kg per day which seems high - what is
> the origin of this figure?
> The right hand part of that figue shows some sort of biomass
production as
> a function of altitude - but I need help with the units. I hope Ray
> Wijewardene (Sri Lanka) and A.D Karve (Pune) will throw in some ideas on
how
> to most efficiently supply biomass on a plantation basis (I think they
will
> promote bamboo).
>
> 6. Section 3.3 (pp 13-15) is very helpful - and I recommend it to
others
> especially on making charcoal briquettes. I don't know enough to ask an
> intelligent question here - but I like your observation that the 19 holes
> gives a superior flame. Anything more on this subject would be
appreciated.
> Any pictures of flames?
>
> 7. Section 4 brings in three other stoves types:
>
> a. The Rocket on p 16. Obviously you know this well - but I hope
Larry,
> Dean and others will look over your comments and offer their comments.
They
> have recently been doing a lot with low mass insulating ceramic/brick
walls
> that you don't mention.
>
> b. The Satellite stove - p 17 I like all the improvements you
show. You
> are getting close here to the work of Lanny Henson - who has a somewhat
> similar design but with a chimney and a method of achieving "swirl" to
lower
> the overall profile. It would seem that a chimney might be a pretty
useful
> addition in high-altitude Nepal - and would avoid the necessity of outdoor
> lighting.
>
> c. The Paru stove (p 18) was new to me by this name - but the
name of Dr.
> Grover has been mentioned several times in the past with almost this same
> design (I saw two much larger versions in Zimbabwe in 1995 attributed to
> Grover). I understood that the power control was not good and wonder if
> that is still true. "Stoves" list member Auke Koopmans was listed as the
> author of this report and I hope he will tell us if this Paru stove ever
> reached a commercial stage?
> I tried to find the cited reference through REPP - but found the
paper
> missing (Tom Miles take note). But I eventually found it at
> http://www.rwedp.org/acrobat/rm56.pdf
> The description called for the addition of a few small pebbles
which stay
> red hot - and I have not previously seen this listed. Anyone with
> experience on this?
>
> I hope that we can hear more about this stove from you or others
familiar
> with it. It appears that it is designed to produce char (with full waste
> heatr utilization) and I am all in favor of that. I believe that a
similar
> design with an air port at the top to allow controllable primary air and
> downdraft might be a distinct improvement (as power level could be
> controlled - and would be sort of an inverse of what I have been working
> on). The claims in this report about clean operation are ones some of us
> have been making and I hope that you or Auke can report if there have been
> any emissions measurements on this Grover stove.
>
> 8. The final page is a very nice summary (the best I know of)
from a 1994
> World Bank report by Kirk Smith and others (I found a copy at Kirk's web
> site as: http://ehs.sph.berkeley.edu/krsmith/Publications/WB_Report.pdf
> Everyone on "stoves" should look at this list, which I reproduce
in poor
> form below (poor as Sjoerd has made bold all those items that are
pertinent
> to his need in Nepal looking at a charcoal briquette burner).
>
> 9. that concludes my thoughts on your paper. Here are a few
small
> questions that will help me/others better understand what is happening in
> Nepal:
>
> a. You used a conversion factor between the Nepalese rupee and
the Euro of
> 80 to one. What is the "minimum" or average wage in your areas of Nepal?
>
> b. Given the very high transportation costs and shortage of
biomass
> materials, it would seem that solar cookers might be a good alternative
for
> both natives and trekkers - at least for when the weather was good. What
is
> the history of any such intervention? Can you tell us more about the
> typical meal? One burner enough? etc
>
> c. Others on "stoves" have considered binders like the 30%
clay-soil which
> you didn't like. Elsen Karstad (Nairobi) uses about 15% and the Karves
> (Pune India) use only waste flour. Can you report on any tests showing
the
> results of variations in clay content?
>
> d. With your numbers for 6 MJ per briquette and 1 hour duration,
you are
> operating at about 1.6 kW. Do you now have any control over that in the
> small system? (airflow control?) How much in the Tibet version?
>
> e. You talk about particulate emission also on p5. How are you
measuring
> this? Better or worse than other types of charcoal stoves? Tami Bond
has
> done a lot of work on particulate emission from holey coal briquettes and
I
> hope she will look at your results. Any chance of getting some sent to
her
> or others?
>
> f. On page 7 you show some air control regulators, but none for
the unit
> on p 5. Is there good or only fair control for the 8-briquette unit? Can
> you estimate the Turndown ratio (ratio of max to min combustion times)?
>
>
> Again thank you for supplying this very comprehensive report. We
need more
> such thorough documentation.
> I think the Dutch development programs are some of the best and
yours is a
> good example. I hope your report will stir some dialog and that my review
> will help you and others to compare and develop new ideas - as there are
> several new areas for us in what you are doing - which I hope I have noted
> above.
>
>
> Ron
>
> End of RWL comments.
>
> The remainder is the nice check list coming from Sjoerd's last page and
> earlier from the Word Bank paper 242. Note the second list is sort of the
> reverse of the first. See Sjoerd's paper for what is bold. The full WB
> paper (60pp) goes into greater detail on many of the criteria.
>
> I wonder if anyone objects to anything on this list or can add any
more?
> For example, my comments in a different message today about beauty in a
> stove - I don't see on this list.
>
>
> Box 4. Possible Reasons for Success or Failure
> Reasons for success
> 1. Program targets region where traditional fuel and
> stove are purchased or fuel is hard to collect.
> 2. People cook in environments where smoke
> causes health problems and is annoying.
> 3. Market surveys are undertaken to assess potential
> market for improved stoves.
> 4. Stoves are designed according to consumer
> preferences, including testing under actual use.
> 5. Stoves are designed with assistance from local
> artisans.
> 6. Local or scrap materials are used in production
> of the stove, making it relatively inexpensive.
> 7. The production of the stove by artisans or
> manufacturers is not subsidized.
> 8. Stove or critical components are mass produced.
> 9. Similar to traditional stove.
> 10. The stove is easy to light and accepts different-sized
> wood.
> 11. Power output of stove can be adjusted.
> 12. The government assists only in dissemination,
> technical advice, and quality control.
> 13. The stove saves fuel, time, and effort.
> 14. Donor or government support extended over at least
> 5 years and designed to build local institutions and
> develop local expertise.
> 15. Monitoring and evaluation criteria and
> responsibilities chosen during planning stages according
> to specific goals of project.
> 16. Consumer payback of 1 to 3 months.
>
>
> Reasons for failure
> 1. Program targets region where traditional fuel or
> stove are not purchased or fuel is easy to collect.
> 2. People cook in the open, and smoke is not really
> a problem.
> 3. Outside "experts" determine that improved stoves
> are required.
> 4. Stove is designed as a technical package in the
> laboratory, ignoring customers' preferences.
> 5. Local artisans are told or even contracted to build
> stoves according to specifications.
> 6. Imported materials are used in the production of
> the stove, making it expensive.
> 7. The production of the stove by artisans or
> manufacturers is subsidized.
> 8. Critical stove components are custom built.
> 9. Dissimilar to traditional stove.
> 10. The stove is difficult to light and requires the
> use of small pieces of wood.
> 11. Power output cannot be easily controlled.
> 12. The government is involved in production.
> 13. The stove does not live up to promised
> economy or convenience under real cooking
> conditions.
> 14. Major achievements expected in less than 3
> years, all analysis, planning, and management done
> by outsiders.
> 15. Monitoring and evaluation needs are not planned
> and budgeted, or criteria are taken uncritically from
> other projects or not explicit I y addressed.
> 16. Consumer payback of more than 1 year.
>
>
>
>
>
> Ron
>
>
> >-----Original Message-----
> >From: Ron Larson [mailto:ronallarson@qwest.net]
> >Sent: Wednesday, March 19, 2003 5:59 PM
> >To: Sjoerd Nienhuys; STOVES@LISTSERV.REPP.ORG
> >Subject: RE: [STOVES] Beehive report
> >
> >
> >Sjoerd and stovers:
> >
> > The right reference for this site/cite is
> >http://www.repp.org/discussiongroups/resources/stoves/Nienhuys/Beeh
> >ive%20Stove.pdf
> >
> > Tom Miles has done a great job in adding photos and longer
> >reports like Sjoerd's.
> >
> > I haven't read this yet, but note that Sjoerd is using the
> >19-hole "holey" briquette design. It looks quite complete, with
> >reference to many of the things we talk about. Thanks to Sjoerd
> >for getting this to us.
> >
> >Ron
> >
> >
>
> <snip>
> >>
> >>Sjoerd Nienhuys
> >>Senior Renewable Energy Advisor
> >>SNV/N, Netherlands Development Organisation
> >>P.O. Box 1966, Kathmandu, Nepal
> >>Telephone: ++997-1-5523444
> >>snienhuys@snv.org.np
> >>
> >>
>
>

From ventfory at IAFRICA.COM Mon Mar 24 02:06:32 2003
From: ventfory at IAFRICA.COM (Kobus)
Date: Tue Aug 10 18:30:19 2004
Subject: Ceramic charcoal stove
Message-ID: <MON.24.MAR.2003.090632.0200.VENTFORY@IAFRICA.COM>

Crispin and all,

I apologise for throwing this in amongst all the other important discussions going on.

I made two holes (3/4 inch) halfway up the ceramic sleeve (above the level of the fuel) to provide secondary air, as advised by Crispin. I drilled them with a hole-saw, directly in line with each other. Note that the secondary air is not heated. It gave a very interesting result: Two horizontal columns of blue flames protruded from the respective holes and met in the middle. I did limit the amount of primary air in this experiment, when I don't limit the primary air flow the effect of the secondary air is less striking, but in my opinion does still clean up combustion by burning off excess CO. I will take a picture of the flame, and post it to Tom. A picture of my first prototype will follow a bit later as it is currently being used by a family and I would like to give them my second prototype before removing the first.

Kobus
ventfory@iafrica.com

From snienhuys at SNV.ORG.NP Mon Mar 24 02:16:32 2003
From: snienhuys at SNV.ORG.NP (Sjoerd Nienhuys)
Date: Tue Aug 10 18:30:19 2004
Subject: Beehive report
In-Reply-To: <NGBBKDEHILILFNJPHEFIAELECKAA.ronallarson@qwest.net>
Message-ID: <MON.24.MAR.2003.130132.0545.SNIENHUYS@SNV.ORG.NP>

RON and All,

Please see text marked > ad - 1 etc.

-----Original Message-----
From: The Stoves Discussion List [mailto:STOVES@LISTSERV.REPP.ORG]On
Behalf Of Ron Larson
Sent: Sunday, March 23, 2003 12:50 PM
To: STOVES@LISTSERV.REPP.ORG
Subject: Re: [STOVES] Beehive report

Sjoerd (cc Stovers):

This is mainly to follow up on my note of March 19 on your very
interesting
stoves work in Nepal (citation given again today by Tom Miles) with some
questions:

1. It appears that your paper was designed to set down all of the
good and
bad aspects of the various stoves you are now considering for high altitudes
in Nepal. You have done a nice job in doing this - but it appears that you
are still not quite settled on a choice - and are perhaps looking for
comments. Is this correct? We have few discussions of stoves for heating
and this is a good application for further discussion.

> ad 1. The paper analysed basically the available beehive stove with its
problems at the high altitude (over 2500m). It looked at how, on the basis
of the existing practice and available technology, improvements could be
realised. No choice has been made, but I think that combining the beehive
with the rocket stove design will improve usability as well as performance.
For outside use in high altitude areas the shield seems to be essential.
Making a light-weight (low mass) internal stainless steel chamber (locally
available) seems to be a good addition.

2. Assuming this is so, I've got a few questions and comments
below.

> ad 3-1. Some "beehive" are well made, mainly because they use fine clay.
When briquettes are used in the neighbourhood, the compacting is less
critical. When they need to be used by fussy tourists, they need to be very
well made.

The part I found most interesting here was in the "charring process"
figure
on p4. This method is similar to the "downdraft method" developed by Elsen
Karstad in Nairobi for sawdust, bagasse, and similar material. This is to
ask Elsen to comment. Both of you are adding material and the pyrolysis
front is moving upward. One difference is that yours requires a final
period in which the material just "cooks". I think others like the Karves
should look at this design for a possibly useful approach in their
production of charcoal also from ag residues (and you should look at
theirs).

> ad 3-2. This charring process is common here and works well, especially
with small-sized bio-mass. The process can be further exploited because in
urban areas plenty wood waste is available and burning wood fires remains a
smoky affair. In this case the smoke is produced in the forest, while
in-house air pollution is minimised. Many restaurant owners use the
briquettes in large tunnel shaped improved mud-cook stoves; clean fuel,
improving heat and simple to store. Reducing in-house air pollution is most
appreciated by the cook (usually women).

My own interest has been in producing charcoal while cooking - but
don't
think I could use your raw materials. But I do hope you will look at ways
to make charcoal and simultaneously use the large amount of potentially
useful heat flared in your pyrolysis gases.

> ad 3-3. We may try to insert biomass in the outside (insulating cavity)
chamber so gases enter into the burning chamber. After the biomass is
charred, it can be used in a new cooking cycle inside the burning chamber as
fire material. This way the burnable components of the smoke are not going
to waste in the forest. It is my experience, however, that if we make too
many changes at once, it will complicate the development process. Also if
the new stove is too much different from the old stove, villagers will not
easily accept the design and marketing becomes a problem.

> ad 4-1. I found that where we are struggling with some technical
applications, in China they have long solved and completely commercially
marketed the ideas in China and Tibet. Look for example at the vacuum tube
solar water heater, the low parabolic solar cooker, the bow-shaped green
houses, the Samovar cooker, the small food sizes they use in food
preparation, the Wok, use of dried food stuffs. The three briquette stove
of Tibet (4000 m) solves most problems I found in Nepal high altitude areas
(3000-4000m), so my suggestion was that local organisations look first at
that stove design and its manufacturing, instead of "inventing" new stoves.

Your figure on p 10 reminds me that you might consider preheating of
your
air supply - by moving the air supply hole up to the top of the stove, with
the air then picking up temperature as it traverses down to the bottom of
the briquettes. This is the crux of much of the "stoves" dialog on
preheating still going on - being led by Crispin.

> ad 4-2. I follow pre-heating with interest. Also refer to 3-3 above. We
may think up a perfect solution and than the villagers copy something else
from oil barrels. Observing the burning process in the briquettes (without
instruments) we notice that the better the sides are insulated the more
complete is the burning process and less ashes are produced. The two
briquette high stove will also enhance the burning, and provide longer as
well as higher heat. Wall insulation (as per rocket stove) will definitely
improve combustion. Therefore I choose these as first improvements. It
is the local NGO or research company that needs to realise the works.
When I make holes in the outside top of the Tibet stove, and on the inside
bottom, it will work. If I do this in the stove design in which I want to
char biomass (using the cavity), the smoke will get pressed out of these top
holes instead of the bottom inside holes, defeating the other objective. I
see more benefit of using the gas than preheating air.

But Crispin (and some others of us) are interested in separating
primary
and secondary air and controlling both when the fuel is biomass. It appears
that with a charcoal-burning stove there may be a need only for the primary
air and I hope others will jump in on whether that is true. Anyone know of
any successful charcoal burning stoves where the secondary air component is
critical?

> ad 5-1. Nearly three tons per year (family 5 pers) is an average figure
repeatedly assessed in Nepal by various surveys and user reports. The
figure is collaborated by surveys in Myanmar (FAO report 56). Everybody
agrees that the figure is high and the cause of severe deforestation. Some
improved cooking stove (ICS) programmes have been initiated in Nepal, some
not effective at all.

The right hand part of that figue shows some sort of biomass
production as
a function of altitude - but I need help with the units. I hope Ray
Wijewardene (Sri Lanka) and A.D Karve (Pune) will throw in some ideas on how
to most efficiently supply biomass on a plantation basis (I think they will
promote bamboo).

> ad 5-2. The table shows that at higher altitudes the imbalance between
consumption and supply is getting worse because biomass re-generation is
rapidly decreasing with the altitude. The figures are rather estimative,
because they are influenced by slope, wind, sun side, humidity and soil
condition. Anyhow all the arable land has been taken over by the farmers.
Bamboo is only in some parts an option because it is sensitive to humidity
levels as well as soil drainage, and restricted to a limited altitude range.
Villagers do not like the bamboo for firewood because of sharp edges and
difficult chopping. Bamboo when available is used in construction, which I
would prefer. Used once in thermal insulation or greenhouses it saves energy
for many years.

6. Section 3.3 (pp 13-15) is very helpful - and I recommend it to
others
especially on making charcoal briquettes. I don't know enough to ask an
intelligent question here - but I like your observation that the 19 holes
gives a superior flame. Anything more on this subject would be appreciated.
Any pictures of flames?

> ad 6 Yes, the picture on the front page is a briquette burning full blast.
The flame is so clean that I have to think of a special camera set-up to
make it visible.

7. Section 4 brings in three other stoves types:

a. The Rocket on p 16. Obviously you know this well - but I hope
Larry,
Dean and others will look over your comments and offer their comments. They
have recently been doing a lot with low mass insulating ceramic/brick walls
that you don't mention.

> ad 7-a The locally manufactured Rocket stove is of made of thick metal
and heavy, with a loose shield, and not at all appreciated by villagers.
Any separated component will not be used. The contraption must be locally
made and ceramic tiles is not an article you want to carry five days up a
hill when you are already out of breath. My observations are strongly
linked to the high altitude problems. So I think to organise a trial
testing with light-weight stainless steel and an air insulated cavity
chamber. The stainless steal pot is very much available here in all sizes.
The special advantage is that the stove can be made in components, thus no
welding required. At most of the high altitude areas in Nepal there is no
electricity.

b. The Satellite stove - p 17 I like all the improvements you
show. You
are getting close here to the work of Lanny Henson - who has a somewhat
similar design but with a chimney and a method of achieving "swirl" to lower
the overall profile. It would seem that a chimney might be a pretty useful
addition in high-altitude Nepal - and would avoid the necessity of outdoor
lighting.

> ad 7-b I first tried to include the Lanny-cut fire-box design in the
bottom opening of the ash/feeder box. But considering pre-fabrication and
assembly options, and the fact that the pot would not sink into the burning
chamber, the more complicated Lanny-cut would probably not give the
advantages.

> ad 7-c. The Paru stove brings the idea of gassifying the biomass. Because
thermal insulation of the burning chamber is created between the inner and
outer chamber, and thermal insulation is improved by restricting
air-circulation; air circulation can be reduced by filling the cavity wall
with biomass. That biomass will gassify (as per Paru stove and charcoal
burner) . When the smoke is produced it can be co-burned when led into the
bottom of the inner chamber.

I tried to find the cited reference through REPP - but found the
paper
missing (Tom Miles take note). But I eventually found it at
http://www.rwedp.org/acrobat/rm56.pdf

>ad website: correct, the reference must be the above www.rwedp.org

The description called for the addition of a few small pebbles which stay
red hot - and I have not previously seen this listed. Anyone with
experience on this?

I hope that we can hear more about this stove from you or others
familiar
with it. It appears that it is designed to produce char (with full waste
heatr utilization) and I am all in favor of that. I believe that a similar
design with an air port at the top to allow controllable primary air and
downdraft might be a distinct improvement (as power level could be
controlled - and would be sort of an inverse of what I have been working
on). The claims in this report about clean operation are ones some of us
have been making and I hope that you or Auke can report if there have been
any emissions measurements on this Grover stove.

8. The final page is a very nice summary (the best I know of) from
a 1994
World Bank report by Kirk Smith and others (I found a copy at Kirk's web
site as: http://ehs.sph.berkeley.edu/krsmith/Publications/WB_Report.pdf
Everyone on "stoves" should look at this list, which I reproduce in
poor
form below (poor as Sjoerd has made bold all those items that are pertinent
to his need in Nepal looking at a charcoal briquette burner).

9. that concludes my thoughts on your paper. Here are a few small
questions that will help me/others better understand what is happening in
Nepal:

a. You used a conversion factor between the Nepalese rupee and the
Euro of
80 to one. What is the "minimum" or average wage in your areas of Nepal?

> ad 9-a. Average income is about One Euro per day, but for most rural and
subsistence farmers that is still out of reach. It are the very low-income
people that bring a heavy toll on the forest reserves (3 ton wood
/year/family). The implication is that new stove designs must be low-cost
(less than 10 Euro) durable (stainless steal), easy to handle, repair and
maintain (no welding), and easy to understand (low-income often goes
together with down to earth simplicity) and handy (move around "satellite"
stove). The satellite is referring to the moving around, not to the end of
the Rocket. People who have cattle (also if they have a biogas reactor
that covers their cooking needs) make an open (three-stone) fire outside
the house to cook the swill or cattle food. With a good satellite stove in
which they can either burn wood, agric residue or briquettes, and they can
also make a small dish if so wanted (warm up food), they may buy the
product.
What I am trying to convey is that we would not be looking solely to the
most efficient stove, but rather to make a better product for the identified
market or problem.

b. Given the very high transportation costs and shortage of
biomass
materials, it would seem that solar cookers might be a good alternative for
both natives and trekkers - at least for when the weather was good. What is
the history of any such intervention? Can you tell us more about the
typical meal? One burner enough? etc.

>ad 9-b. One domestic burner is often OK, but for restaurants and lodges the
multi-burner and mud-tunnel (Estufa Lorena type) ICS are commonly used,
eventually with smoke water heater or back burner (GI pipes in the tunnel).
Most trekker hotel facilities have Solar Water Heater for warm water, but
freezing at night makes them to drain the equipment off (tourist) season.
These SWH we are now slowly improving. Parabolic solar cookers are
spacious, need regular re-orientation, are very wind sensitive (except the
Tibet model), are currently subsidised and are not liked at all by trekkers
or hotels. Several models exist, but cannot compete with kerosene burners
in utility.
The key words are here reliance and utility. Trekking guides cannot tell
the tourist "sorry no tea or meal because the solar cooker does not work" .
So in case a solar cooker is brought, alongside the kerosene burner is still
needed. Whether the tourist is paying Euro 25 per day or Euro 30, who
cares, not even the tourist.

With FoST and CRT in Nepal we may be look at improving the designs. I am
more busy with Thermal Insulation of houses and SWH as these give the most
savings on firewood as compared to stoves. Designing stoves for people who
do not have money to buy them is not a business venture for local industry.
Introducing more efficient stoves to subsistent farmers requires an
integrated rural development support package alongside, which is
complicated. We are working on that as well.

c. Others on "stoves" have considered binders like the 30%
clay-soil which
you didn't like. Elsen Karstad (Nairobi) uses about 15% and the Karves
(Pune India) use only waste flour. Can you report on any tests showing the
results of variations in clay content?

>ad 9-c. Clay soil binder is OK as long as the clay content is very high.
When pure clay content drops, more ashes result. Even the local villagers
will tell this. In remote areas some plastic waste shopping bags are a
possible binder (when shredded). Related to the general poverty level in
the regions, and the fact that each morsel of food or edible product is fed
to animals, there is little room for other binders. Best option is to have
a simple method of purifying the clay. The criteria of the clay content is
the stability of the brick to allow easy transportation, without
disintegrating, making a mess.

d. With your numbers for 6 MJ per briquette and 1 hour duration,
you are
operating at about 1.6 kW. Do you now have any control over that in the
small system? (airflow control?) How much in the Tibet version?

> ad 9-d. The 6MJ is merely based on the value of charcoal (mixed with
clay-soil). One of the problems of the open Khumbu stove was its inability
to control air-flow. The Tibet stove has the two-opening air-flow control.
With both vents open in the Tibet 3-briquette stove, a very hot fire is
pushed due to the height, the coal briquettes and the thermal insulation of
the wall.

e. You talk about particulate emission also on p5. How are you
measuring
this? Better or worse than other types of charcoal stoves? Tami Bond has
done a lot of work on particulate emission from holey coal briquettes and I
hope she will look at your results. Any chance of getting some sent to her
or others?

>ad 9-d . This was (allegedly) measured by RONAST -Nepal and reported to me
by CEE. The problem is manly related to the impure Lignite, but I
understand that also coal should not be burned in an open fire inside the
house. I have no measurement results on coal and our focus will be on the
charcoal stove as possible renewable energy resource, also for low land
forest areas.

f. On page 7 you show some air control regulators, but none for the
unit
on p 5. Is there good or only fair control for the 8-briquette unit? Can
you estimate the Turndown ratio (ratio of max to min combustion times)?

> ad 9-f. I have no experience of using of the depicted BBQ stove, but the
air-intake is also for firing-up the briquettes. Once burning, the
regulators can be pushed down a little. The CEE were not selling the stove
at all, this was merely a prototype, they said worked well. Making a stove
is one problem, marketing the stove and the fuel briquettes is another. The
stoves on p6 have no regulators, one of the weaknesses. Usually one
briquette is placed and let it burn, finish.

Again thank you for supplying this very comprehensive report. We
need more
such thorough documentation.
I think the Dutch development programs are some of the best and
yours is a
good example. I hope your report will stir some dialog and that my review
will help you and others to compare and develop new ideas - as there are
several new areas for us in what you are doing - which I hope I have noted
above.

Ron

End of RWL comments.

I wonder if anyone objects to anything on this list or can add any
more?
For example, my comments in a different message today about beauty in a
stove - I don't see on this list.

> ad. I agree that beauty, prestige and space utilisation are other
aspects.

Ron

<snip>
>>
>>Sjoerd Nienhuys
>>Senior Renewable Energy Advisor
>>SNV/N, Netherlands Development Organisation
>>P.O. Box 1966, Kathmandu, Nepal
>>Telephone: ++997-1-5523444
>>snienhuys@snv.org.np
>>
>>

From crispin at NEWDAWN.SZ Mon Mar 24 03:11:29 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: Ceramic charcoal stove, Maendeleo variations
Message-ID: <MON.24.MAR.2003.101129.0200.CRISPIN@NEWDAWN.SZ>

Dear Kobus

1. The "Two horizontal columns of blue flames ..." indicate that you have
unburned fuel gases and probably a high CO level reaching the pot. it is
likely that opening these holes reduced the primary air draw a little and in
effect you are creating the need for your solution. In other words, the
'need for secondary air' can be a self-fulfiling prophecy if your solution
reduces primary air feed and creates CO!

2. When you 'limit the amount of primary air ...' it creates even more of
a problem (need for secondary air) but in my experience most stoves with
only primary combustion have burnable fuel going 'up the chimney' so to
speak. It is extremely difficult to get very low CO levels without
secondary combustion unless it is a true gasifier with a gas burning head.
CO is a poison and when people light fires indoors (a very common practice
in this region) they poison themselves. Driving up the initial combustion
temperature (using draft, insulation, etc.) tends to increase the production
of NOx's which are lung irritants. In an environment of TB and reduced
immune system effectiveness these gases are real problems. Achieving the
combination of low NOx and low CO is difficult without having secondary
combustion designed into the stove. Although the talk from me has always
been about getting the secondary heated, it is not anything like the
temperature of a fire. The fire temperature should actually be held down
while still retaining complete combustion. That requires post-primary
'treatment' and effective mixing.

3. There is probably a measure of preheating of the secondary air
happening even though you did not seek it specifically because the ceramic
does get hot and the air passes through it. If you have a high temp
thermometer you could measure the air temp as it goes in.

4. If you can provide the secondary air in a way that does not allow in
excess air when you don't need it, you can vary the primary air and have a
variable energy stove, more like a Handigas cooker.

5. I think that if the Maendeleo clay stove makers in Kenya and Malawi
did exactly what you did it would improve combustion efficiency and bring
the hottest part of the flames closer to the bottom of the pot, rather than
letting them 'chill' up the sides. I would like to see the holes about 10mm
in diameter (through the clay) and angled so they pointed upwards and
inwards. I would try 30 holes to start, placed in a circle about 80mm below
the top of the stove, maybe 100mm. This angling will increase their length
and allow for more heat pickup from the clay body. At some point (hole dia
and spacing) the heat exchange is optimized reducing body losses and getting
the combustion efficiency up while allowing for a reduction of primary air
inflow, which in turn increases heat transfer as the gas velocities reduce
past the pot.

It is a very cheap and easy way to provide some preheated secondary air to a
clay 'sheltered fire'. Once the stove has been going for a while there is
considerable heat stored in the clay and some of this can be recycled into
the fire.

Clearly the Maendeleo stove would also benefit from a pot shield, made from
clay if that is all there is. This also increases (potential) draft and
increases the secondary air injection velocity promoting better mixing.
Optimized in this layout, I expect that the PHU of the Maendeleo can be
improved from its present level (about 20%) to 25 to 30%. It would still
only cost about a Dollar to build.

Good luck!
Crispin in Matsapha

From crispin at NEWDAWN.SZ Mon Mar 24 04:23:25 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: RE Beehive report
Message-ID: <MON.24.MAR.2003.112325.0200.CRISPIN@NEWDAWN.SZ>

Dear Stovers

Just this one little comment:

>Anyone know of any successful charcoal burning
>stoves where the secondary air component is critical?

As charcoal appears to be able to produce CO at a fairly low temperature it
is clear to me that without some secondary air provision, deliberate or
accidental, the combustion will suffer. The fact that 'it doesn't smoke'
when it is burning doesn't mean much as CO is clear, giving the (dangerous)
impression that combustion is complete.

John Davies' coal gasifier was tested by the Harare lab equipment
demonstrators (ProBEC) in Vereeniging and with preheated secondary air it
was running at about 150 ppm CO. That is pretty good for some of the worst
coal I have ever seen. According to my understanding of the gases produced
(a great deal of CO), there isn't a whole lot of difference between that and
burning charcoal.

Regards
Crispin

From crispin at NEWDAWN.SZ Mon Mar 24 15:39:59 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: More secondary air
Message-ID: <MON.24.MAR.2003.223959.0200.CRISPIN@NEWDAWN.SZ>

Dear Stovers

Although there has been little response to the question of the secondary air
issue, I will continue with a little analysis based on further thoughts.

To review briefly, John Davies put a secondary air preheating shroud around
the outside of the top of his stove, just below the working surface. Heat
trapped inside it increased the temperature of the secondary air. I don't
have measurements. He reported that the amount of heat transferred to the
pot (as a percentage of the heat in the coal) increased from 19% to 25%.
This is a very high figure for a coal stove in the first place as it is very
difficult to burn coal efficiently in a small fire of only a few hundred
grams so a number of things must be right.

I postulated that this showed the benefits of preheating the secondary air,
however it occurs to me that the shroud accomplished two (or more) things
simultaneously and therefore it will be difficult tease out the influence of
heat in the secondary air alone.

When the shroud is placed around the top of the stove, it inevitably raises
the temperature of what was the outside layer of the stove, reducing losses
to the outside air and probably raising the temperature of the gasses
passing round the pot - in his case a kettle. Thus, the effective increase
in the heat transfer may have been partly or entirely due to the insulating
nature of the shroud and might have very little to do with the heat in the
secondary air or improved combustion efficiency.

To prove this, one could wrap an insulating blanket around the stove in
place of the preheating shroud and see of the same or similar gain was
obtained. The insulator should not impinge on the (cold) secondary air flow
and should be in perhaps two layers so that more influence can be seen with
more insulation.

When this is tried, the gain may not have increased as much as from 19 to
25%. Let us presume the insulation gives less than a 6% increase. Then the
secondary air preheater could be replaced and the gain checked. If it is as
before, a 6% rise, then the difference between the insulated version's gain
and the secondary air preheated version's gain would be due to the secondary
air preheating alone. There may be a change in CO in the chimney.

To top it off, the insulation could be wrapped around the outside of the
secondary air preheating shroud to see if it went up still further. Again,
simple subtraction would yield the gain due to preheated air alone, if any.

On a more theoretical basis, I feel that maintaining good combustion of
gasses in a coal gasifier will be helped by inrushing hot air mixing as well
as possible just before or during burning. As the heat for doing so is
usually leaking out of the stove anyway it seems prudent to capture it and
send it back in, using the free air supply to act as an insulator. In this
way a combination of low NOx and CO can be attained simultaneously, even
using vile and erratic types of coal, and a stove without any ceramic parts
or insulation. But all that does not mean that the secondary air has to be
preheated to achieve such a clean result. The experiment has not yielded a
conclusive proof.

As I mentioned, the Vereeniging conference test showed a CO of about 150ppm
for John's coal stove, or about double that of a Vesto. The Vesto is only a
semi-gasifier and it has a far higher quality of fuel (biomass) to start
with, thus more predictability and so the better result in expectable. It
would have been useful to have a CO test with the secondary air shroud
removed to see if the effect of it was primarily insulative, heat recycling
or combustive.

At the moment my hunch is that the combustive element is the minor of the
three.

Anyone have other ideas?

Regards
Crispin

From ronallarson at QWEST.NET Mon Mar 24 23:21:26 2003
From: ronallarson at QWEST.NET (Ron Larson)
Date: Tue Aug 10 18:30:19 2004
Subject: FW: [ethos] Fw: justa pix
In-Reply-To: <3E7F9377.E643DC3C@treeswaterpeople.org>
Message-ID: <MON.24.MAR.2003.212126.0700.RONALLARSON@QWEST.NET>

Stuart et al

Thanks for the further discussion. Just a few more questions:

1. I was asking about avoiding baffles altogether - but rather using a
combustion region that instead of being of uniform cross-sectional area,
widens uniformly as one approaches the plancha - maybe even to the full
plancha width (apparently usually 22 inches). It seems that Don O'Neil may
have tried this and I wondered what his results were (or anyone elses)?
Have the stoves supported by TWP always had a "straight" combustion region -
as in all the Rockets I have seen?

2. I can conceive of a close-to-vertical central dividing surface that
might allow one to put most of the energy on one side of the plancha
(presumably away from the chimney - but not necessarily) or alternatively
(by sliding top and bottom edges separately horizontally) try for a more
uniform temperature (for different types of cooking). (I am thinking of
something that would add a few bucks to the price. Anyone heard of such a
scheme? (Think of a "Vee" in crosssection with a somewhat shorter
horizontally moveable "I" in between with the chimney on one side of the "V"
and the horizontal plancha across the top of the "V"

3. After my question about measuring efficiency on such stoves, I
remembered visiting the Ethiopian national stove lab (before it was killed
in an unfortunate budget cutback maybe 10 years ago). I saw a woman
employee who spent the entire day making the big (60 cm) enjiras on stoves
of different types. The efficiency measure was in kg of wood per kg of
enjira, I think (thereby not worrying too much about the number of enjira,
I recall - but the woman was keeping track of both and trying for a uniform
product). I wonder if the same measure wouldn't be valid for comparing
different plancha-type stoves. Any estimates by anyone on this FOM for
tortillas? Should be roughly comparable with the enjira number (which I
don't know - but might be able to find.

Stuart - thanks for your strong support for all those thousands of stoves.

Ron
-----Original Message-----
From: owner-ethos@vrac.iastate.edu [mailto:owner-ethos@vrac.iastate.edu]On
Behalf Of Stuart Conway
Sent: Monday, March 24, 2003 4:24 PM
To: Ron Larson; Stoves Discussion List; Ethos
Cc: Richard Fox
Subject: Re: FW: [ethos] Fw: justa pix

Hi Ron et al,
Let me answer some of your questions and comments below:

<snip>

From Visser at BTGWORLD.COM Tue Mar 25 06:42:17 2003
From: Visser at BTGWORLD.COM (Piet Visser)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing
Message-ID: <TUE.25.MAR.2003.124217.0100.VISSER@BTGWORLD.COM>

Dear Stovers,

This is mainly in reaction to Crispins long mail about testing.

Testing should be done with a lid on the pan and the use of a lid should
indeed be part of household management training. And this stresses the
importance of this kind of training. In most cases improved household
management could generate as much fuel saving as the introduction of an
improved stove. And an improperly used improved stove can use as much fuel
as the traditional fire.
The lid will reduce heatloss during heating up. Once the water starts
boiling, the steam will come out, unless we are using a pressure cooker.

Test results only have a meaning for the stove-pan combination tested. As
soon as a stove is used with another pan (other size, other material, other
shape) this new configuration must be tested again. And then the heat
absorbed by the pan is part of the efficiency (or PHU).

In the Netherlands (and probably elsewhere as well) standards have been
developed for gas ranges which make it possible to generate "bare"
efficiency numbers (which can be quoted in leaflets etc.). This is based on
flat bottomed pans and a fixed power/panbottom surface ratio (At the moment
I do not recall if the pan material was specified too, Piet Verhaart, do
you remember?). Because of the large variety of pans and pots used in
developing countries (material and shape), this approach is not feasible in
our field of work.
So we are stuck to a lot of rather boring testing work.

So, although I agree to a large extend to the observations made by Crispin,
I do not agree to the "SIMPLEST MEANINGFUL TEST" he proposes. Lets just use
one testing procedure and then one that produces results that can be used
to evaluate the fuel consumption of a strove-pan combination for the
preparation of tea or porridge as well as for the preparation of a complete
meal.

Best regards to all,

Piet Visser

_____________________________________________________________

Phone : +31 53 489 2897
Direct : +31 53 489 2889
Fax : +31 53 489 3116
E-mail : Office@btgworld.com
Direct : visser@btgworld.com

From crispin at NEWDAWN.SZ Tue Mar 25 10:20:02 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: Stoves testing cont
Message-ID: <TUE.25.MAR.2003.172002.0200.CRISPIN@NEWDAWN.SZ>

Dear Piet

Many thanks for the Dutch input. That sounds like a system that has been
worked out to the point where the 'number' given to a customer has real
meaning.

What would you suggest as the equivalent for us to be able to develop a
stove together over the internet?

>In most cases improved household management could
>generate as much fuel saving as the introduction of an
>improved stove.

In Christa Roth's Malawi project it appears that the household training
saves twice as much as the improved stove! A whopping 60% total.

>Test results only have a meaning for the stove-pan combination tested.

Exactly. Hence my feeling we should include the pot description when there
is a real possibility someone else may try it with a very similar stove.

>In the Netherlands (and probably elsewhere as well)
>standards have been developed for gas ranges which
>make it possible to generate "bare" efficiency numbers

Can you explain what that would be in our case(s)?

>I do not agree to the "SIMPLEST MEANINGFUL TEST"
>he proposes. Lets just use one testing procedure and then
>one that produces results that can be used to evaluate the
>fuel consumption of a strove-pan combination for the
>preparation of tea or porridge as well as for the preparation
>of a complete meal.

No problem. Can we come up with something agreeable?

Many thanks for your input.

Regards
Crispin

From lanny at ROMAN.NET Tue Mar 25 22:05:51 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:19 2004
Subject: Possible griddle burner /Re: [STOVES] FW: [ethos] Fw: justa pix
Message-ID: <TUE.25.MAR.2003.190551.0800.LANNY@ROMAN.NET>

Dear Ron and Stovers,
You mentioned a griddle burner and a "V" shape. Well it sounds like
something from the stove graveyard that may be a possible spit ball on the
ceiling so to speak. A multiple chimney rocket burner.
http://www.lanny.us/3br.html about 90KB
http://www.lanny.us/3br1.jpg a 26KB photo
Lanny Henson

----- Original Message -----
From: Ron Larson <ronallarson@QWEST.NET>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Monday, March 24, 2003 8:21 PM
Subject: Re: [STOVES] FW: [ethos] Fw: justa pix

> Stuart et al
>
> Thanks for the further discussion. Just a few more questions:
>
> 1. I was asking about avoiding baffles altogether - but rather using a
> combustion region that instead of being of uniform cross-sectional area,
> widens uniformly as one approaches the plancha - maybe even to the full
> plancha width (apparently usually 22 inches). It seems that Don O'Neil
may
> have tried this and I wondered what his results were (or anyone elses)?
> Have the stoves supported by TWP always had a "straight" combustion
region -
> as in all the Rockets I have seen?
>
> 2. I can conceive of a close-to-vertical central dividing surface that
> might allow one to put most of the energy on one side of the plancha
> (presumably away from the chimney - but not necessarily) or alternatively
> (by sliding top and bottom edges separately horizontally) try for a more
> uniform temperature (for different types of cooking). (I am thinking of
> something that would add a few bucks to the price. Anyone heard of such a
> scheme? (Think of a "Vee" in crosssection with a somewhat shorter
> horizontally moveable "I" in between with the chimney on one side of the
"V"
> and the horizontal plancha across the top of the "V"
>
> 3. After my question about measuring efficiency on such stoves, I
> remembered visiting the Ethiopian national stove lab (before it was killed
> in an unfortunate budget cutback maybe 10 years ago). I saw a woman
> employee who spent the entire day making the big (60 cm) enjiras on stoves
> of different types. The efficiency measure was in kg of wood per kg of
> enjira, I think (thereby not worrying too much about the number of
enjira,
> I recall - but the woman was keeping track of both and trying for a
uniform
> product). I wonder if the same measure wouldn't be valid for comparing
> different plancha-type stoves. Any estimates by anyone on this FOM for
> tortillas? Should be roughly comparable with the enjira number (which I
> don't know - but might be able to find.
>
> Stuart - thanks for your strong support for all those thousands of stoves.
>
> Ron
> -----Original Message-----
> From: owner-ethos@vrac.iastate.edu
[mailto:owner-ethos@vrac.iastate.edu]On
> Behalf Of Stuart Conway
> Sent: Monday, March 24, 2003 4:24 PM
> To: Ron Larson; Stoves Discussion List; Ethos
> Cc: Richard Fox
> Subject: Re: FW: [ethos] Fw: justa pix
>
>
> Hi Ron et al,
> Let me answer some of your questions and comments below:
>
> <snip>
>

From lanny at ROMAN.NET Tue Mar 25 22:53:10 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:19 2004
Subject: Griddle Cooking on the Camp Stove #6A
Message-ID: <TUE.25.MAR.2003.195310.0800.LANNY@ROMAN.NET>

Dear Stove Friends,
This is my second batch of tortillas on the Camp Stove #6A. The griddle top
is 16ga and I spot welded a ply of 10 ga ss to it to add some mass, it
weighs 7.25lb and is 11"/28 cm X 14"/36 cm.
That is almost too much mass to cook a meal for two of tortillas. They have
so little moisture to vaporize. But when I put on some wet ground beef the
temp dropped quickly. More mass would be good for cooking ground meat, to
store up a little heat, since the stove has a low energy output.
The stove is a little slow to start (about 10 or 15 min) but after it gets
hot, it functions well at low output and is easy to use. You can walk away
for 20 or 30 min and easily restart. Just push the sticks forward and blow
on the coals.
http://www.lanny.us/gr.html about 150 kb
http://www.lanny.us/gr5.jpg 18 kb

Lanny Henson

From stoves at ECOHARMONY.COM Wed Mar 26 05:07:49 2003
From: stoves at ECOHARMONY.COM (Grant Ballard-Tremeer)
Date: Tue Aug 10 18:30:19 2004
Subject: lids Re: [STOVES] Stove testing
In-Reply-To: <4.2.0.58.20030325120950.00b72720@192.168.10.1>
Message-ID: <WED.26.MAR.2003.100749.0000.STOVES@ECOHARMONY.COM>

Stovers,

On the question of lids, Piet wrote:

PV> Testing should be done with a lid on the pan and the use of a lid
PV> should indeed be part of household management training. And this
PV> stresses the importance of this kind of training. In most cases
PV> improved household management could generate as much fuel saving
PV> as the introduction of an improved stove. And an improperly used
PV> improved stove can use as much fuel as the traditional fire. The
PV> lid will reduce heatloss during heating up. Once the water starts
PV> boiling, the steam will come out, unless we are using a pressure
PV> cooker.

The lid will reduce heat loss during the boiling phase too, and the
'goodness of fit' of the lid does, I believe, have an impact on the
amount of water evaporated (depending on how vigorous the boiling).
Whether to use lids has in fact been the subject of considerable
debate: initially the VITA international testing standards recommended
the use of lids (December 1982 first edition), but they recommended
that lids are not used in the revised edition (VITA 1985). The reasons
(suggested by Baldwin 1987:262,263) are that "lids proved to be
cumbersome in practice and additionally did not reduce the scatter in
the data but rather increased it." There is some analysis of the
impact of lids (and some other variables) on emissions tests in my
thesis at www.ecoharmony.com/thesis (click on Chapter 4).

Regards
Grant

--
Grant Ballard-Tremeer PhD, visit ECO Ltd on the web at http://ecoharmony.com
64C Fairholme Road, W14 9JY, London
Tel +44-(0)20 7386 7930
Fax +44-(0)870 137 2360 and +44-(0)70 9236 7695
email grant@ecoharmony.com
HEDON Household Energy Network http://ecoharmony.net/hedon
SPARKNET Knowledge Network in Southern and East Africa http://sparknet.info
-------------------

From crispin at NEWDAWN.SZ Wed Mar 26 06:43:25 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: lids & Stove testing
Message-ID: <WED.26.MAR.2003.134325.0200.CRISPIN@NEWDAWN.SZ>

Dear Grant

>Whether to use lids has in fact been the subject of considerable
>debate: ..."lids proved to be cumbersome in practice and additionally
>did not reduce the scatter in the data but rather increased it."

That is useful info. How about taking this approach:

The lid is not used in isolation, but on a pot on a stove. Try the same
stove/pot combination with several different lids of varying masses and
materials and 'fits', or just repeat the same test to find the scatter.

How much variation would we get in the resulting PHU?

Then, take the lids off and repeat the same number tests with different wind
and breeze conditions, room temperature and humidity.

How much variation would we get in the resulting PHU?

Then, compare the test with the lids on, to a real cooking of a meal
(lids-on), and the tests with the lid off to a real cooking of a meal
(lids-on). Which is closer to an actual stove use?

I'll bet that the variation in the PHU with differing lids (which limits the
influence of room conditions a lot) is not significantly different from the
variations one gets when cooking a number of identical meals.

I'll bet that there is much less difference between, on the one hand,
cooking a meal and doing a lids-on test and on the other, cooking a meal and
doing a lids-off test, and further, that the difference between lids-on and
lids-off is much greater than the higher scatter of data encountered when
testing with lids. In principle it is more
realistic/truthful/representative to do tests with the lids on.

If the numbers produced at the very end are going to be used by people
(customers hopefully) to rate a stove's value for money, then the test
should be as realistic a measure of the stove's performance as possible when
doing what it normally does - cooking or space heating etc. I like the
Dutch approach for that reason.

I do understand that there are times when one is checking out something very
minimal in effect and one wants to limit scatter as far as possible. I am
not sure my workshop and testing ability are in that league but there are
certainly others who are. They have my admiration!

Regards
Crispin

PS Who is it in Switzerland with the little low pressure paraffin cooker?

From Visser at BTGWORLD.COM Wed Mar 26 08:40:31 2003
From: Visser at BTGWORLD.COM (Piet Visser)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids
Message-ID: <WED.26.MAR.2003.144031.0100.VISSER@BTGWORLD.COM>

Dear stovers,

Crispin,

If you want to undertake such a series of tests, I wish you "bon courage".
And I am curious to know the results, but I doubt if it is worth the efford.

In the mean time, could we agree on the following "shortcut":
* the use of a lid is more efficient, however badly it fits
* therefore we should encourage the cooks to use lids as much as possible
* therefore we should use lids in our tests
Best regards,

Piet Visser

PS. I have sent test descriptions and fuel consumption caculation
spreadsheets to our webmaster. They should be available on the following
link in the coming days:

www.btgworld.com

click "links", then

www.cookstove.net

click "reports"

"Simple waterboiling test procedure", pdf file with test description;
"Testing Protocol English", pdf file with description of test procedure and
fuel consumption calculations with formulas;
"Fuel Consumption Calculations", xls file in english
"Calcul de Consommation de Combustible", xls file in french

_____________________________________________________________

Phone : +31 53 489 2897
Direct : +31 53 489 2889
Fax : +31 53 489 3116
E-mail : Office@btgworld.com
Direct : visser@btgworld.com

From kmbryden at IASTATE.EDU Wed Mar 26 12:20:58 2003
From: kmbryden at IASTATE.EDU (kenneth mark bryden)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids
In-Reply-To: <4.2.0.58.20030326142404.00bdb5e0@192.168.10.1>
Message-ID: <WED.26.MAR.2003.112058.0600.KMBRYDEN@IASTATE.EDU>

Stovers,

The lids question is a little more complex than this -- Lids in all cases
do not make the stove less efficient. However in many cases they do not add
any efficiency.

In the heatup phase of cooking they can add some efficiency. This appears
as a reduction in the time to reach boiling.

In the cooking phase if the stove /fire has good (very good) turndown they
can result in excellent savings of fuelwood. However, if the same level of
heat is applied to the pot in both cases (pot lid on/pot lid off) there is
negligible savings with the pot lid on. We have shown this in our lab where
we measure instantaneous efficiencies, in the field, and by engineering
model. We are currently writing a paper to document these findings.

During the cooking phase with the pot lid on, at the lowest levels of
flame, the "efficiency" drops significantly.One of the keys here is to
realize that we only care a little about the efficiency and we care a lot
about how much fuel is consumed to cook dinner -- and these are not the
same issue.

Based on this the key issue for potlids is the effectiveness of the stove
at low flame, this includes turndown, stability of flame, emissions and a
variety of other issues.

I am interested in an offline discussion on this topic -- to try to resolve
the disparities in the various reports of efficiencies, there are very few
published reports but there are many (and varying) ad hoc and anecdotal
reports that have not been examined in detail. The first focus would be
agreeing on and being able to reproduce the results.

Mark Bryden

At 02:40 PM 3/26/2003 +0100, you wrote:
>Dear stovers,
>
>Crispin,
>
>If you want to undertake such a series of tests, I wish you "bon courage".
>And I am curious to know the results, but I doubt if it is worth the efford.
>
>In the mean time, could we agree on the following "shortcut":
> * the use of a lid is more efficient, however badly it fits
> * therefore we should encourage the cooks to use lids as much as possible
> * therefore we should use lids in our tests
>Best regards,
>
>Piet Visser
>
>_____________________________________________________________

___________________________________________________________
Kenneth "Mark" Bryden, Ph.D. Assistant Professor
kmbryden@iastate.edu Iowa State University
ph: 515-294-3891 3030 Black Engineering Bldg
fax: 515-294-3261 Ames, Iowa 50011-2161

From tmiles at TRMILES.COM Wed Mar 26 12:52:36 2003
From: tmiles at TRMILES.COM (Tom Miles)
Date: Tue Aug 10 18:30:19 2004
Subject: Fw: MBAULA STOVES
Message-ID: <WED.26.MAR.2003.095236.0800.TMILES@TRMILES.COM>

Please reply to the list ro directly to Hanno Synman hanno@agra.com.na
----- Original Message -----
From: Hanno Snyman
To: STOVES-request@listserv.repp.org
Sent: Sunday, March 23, 2003 11:15 PM
Subject: MBAULA STOVES

CAN ANYONE ASSIST WITH THE FOLLOWING?:

We are looking for MBAULA stoves to sell in Namibia, I believe they come from Zambia but are also available in South Africa.
Anyone with contact info please contact me.

Hanno Snyman
Divisional Manager: Safari Den
A Division of Agra Co-op
Tel: + 264 61 290 9294
Fax: + 264 61 233 060
e-mail: hanno@agra.com.na

From stoves at ECOHARMONY.COM Wed Mar 26 12:58:22 2003
From: stoves at ECOHARMONY.COM (Grant Ballard-Tremeer)
Date: Tue Aug 10 18:30:19 2004
Subject: lids & Stove testing
In-Reply-To: <006701c2f38f$17c5b120$2a47fea9@md>
Message-ID: <WED.26.MAR.2003.175822.0000.STOVES@ECOHARMONY.COM>

Hello Crispin,

Wednesday, March 26, 2003, 11:43:25 AM, you wrote:

C> The lid is not used in isolation, but on a pot on a stove. Try the
C> same stove/pot combination with several different lids of varying
C> masses and materials and 'fits', or just repeat the same test to
C> find the scatter.

C> How much variation would we get in the resulting PHU?

C> Then, take the lids off and repeat the same number tests with
C> different wind and breeze conditions, room temperature and
C> humidity.

C> How much variation would we get in the resulting PHU?

C> Then, compare the test with the lids on, to a real cooking of a
C> meal (lids-on), and the tests with the lid off to a real cooking of
C> a meal (lids-on). Which is closer to an actual stove use?

I think you will find that many of the test combinations you proposed
have already been carried out - back in the 1980s. As I wrote, this
was an issue of significant discussion at the time. In any case if you
do carry out the proposed tests, do make sure you randomize the order
of tests and get someone to carry out the tests who has not already
decided the outcome :-) In addition, if you feel a breeze while
carrying out the tests, best find somewhere sheltered! A breeze will
effect more than water evaporation rates.

C> If the numbers produced at the very end are going to be used by
C> people (customers hopefully) to rate a stove's value for money,
C> then the test should be as realistic a measure of the stove's
C> performance as possible when doing what it normally does - cooking
C> or space heating etc. I like the Dutch approach for that reason.

The purpose of the water boiling test is to compare two stoves in the
(same) laboratory to make design decisions, and select promising
designs for field testing. I would suggest using controlled cooking
tests from the field to rate a stove's value for money.

C> I do understand that there are times when one is checking out
C> something very minimal in effect and one wants to limit scatter as
C> far as possible.

Generally, greater scatter means that you will need to repeat a test
more times to detect a statistically separable result, and this does
not mean 'checking out something very minimal in effect'. From
carrying out 6 repeated tests on each of five stoves I measured the
following efficiencies: 14%, 21%, 20%, 24%, 22%. Only one of these
stoves was statistically different from the rest (the 14% of course).
So scatter can be important even for basic testing. These figures come
from www.ecoharmony.com/thesis/AppdxE.htm

All that said, by all means do use pot lids if they help you improve
your designs or select stoves for field testing. Piet's point is
rather compelling (ie. we should encourage users to use lids,
therefore we should test with lids on).

Regards
Grant

--
Grant Ballard-Tremeer PhD, visit ECO Ltd on the web at http://ecoharmony.com
64C Fairholme Road, W14 9JY, London
Tel +44-(0)20 7386 7930
Fax +44-(0)870 137 2360 and +44-(0)70 9236 7695
email stoves@ecoharmony.com
HEDON Household Energy Network http://www.hedon.info
SPARKNET Knowledge Network in Southern and East Africa http://sparknet.info
-------------------

From stoves at ECOHARMONY.COM Wed Mar 26 13:09:59 2003
From: stoves at ECOHARMONY.COM (Grant Ballard-Tremeer)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids
In-Reply-To: <5.1.0.14.2.20030326105810.01968d98@localhost>
Message-ID: <WED.26.MAR.2003.180959.0000.STOVES@ECOHARMONY.COM>

Wednesday, March 26, 2003, 5:20:58 PM, Mark Bryant wrote:

kmb> The lids question is a little more complex than this -- Lids in
kmb> all cases do not make the stove less efficient. However in many
kmb> cases they do not add any efficiency.

and

kmb> During the cooking phase with the pot lid on, at the lowest
kmb> levels of flame, the "efficiency" drops significantly.One of the
kmb> keys here is to realize that we only care a little about the
kmb> efficiency and we care a lot about how much fuel is consumed to
kmb> cook dinner -- and these are not the same issue.

Indeed, Mark. Very interesting.

In my tests pot lids reduced overall efficiency by reducing water
evaporation in the calculation of simmering efficiency, but reduced
fuel consumed during simmering by a factor of three. From an emissions
point of view, the use of a pot lid reduced total emission masses, but
increased emission factors ? since emission factors are highly
dependent on the quantity of fuel consumed. Reported here:
http://ecoharmony.com/thesis/PhDch4.htm

kmb> I am interested in an offline discussion on this topic -- to try
kmb> to resolve the disparities in the various reports of
kmb> efficiencies, there are very few published reports but there are
kmb> many (and varying) ad hoc and anecdotal reports that have not
kmb> been examined in detail. The first focus would be agreeing on and
kmb> being able to reproduce the results.

I probably can't contribute much since I don't have testing or
research facilities. I can make my data available if there is
interest.

Regards
Grant

--
Grant Ballard-Tremeer PhD, visit ECO Ltd on the web at http://ecoharmony.com
64C Fairholme Road, W14 9JY, London
Tel +44-(0)20 7386 7930
Fax +44-(0)870 137 2360 and +44-(0)70 9236 7695
email stoves@ecoharmony.com
HEDON Household Energy Network http://www.hedon.info
SPARKNET Knowledge Network in Southern and East Africa http://sparknet.info
-------------------

From crispin at NEWDAWN.SZ Wed Mar 26 10:01:48 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids - Mark
Message-ID: <WED.26.MAR.2003.170148.0200.CRISPIN@NEWDAWN.SZ>

Dear Mark

Thanks for that.

>In the heatup phase of cooking they can add some efficiency.

It is this particular test which appears to be a litmus test of how 'good' a
stove is among Stovers, even though cooks would appear to appreciate faster
match-to-useful-heat times and less fuel required during cooking.

>In the cooking phase if the stove /fire has good (very good) turndown they
>can result in excellent savings of fuelwood.

I am with you 100% there. Cooks claim that turndown is important.

>However, if the same level of heat is applied to the pot in
>both cases (pot lid on/pot lid off) there is negligible savings
>with the pot lid on.

Is this because there is a lot of water boiled out (more, or just as much)
when the lid is on negating possible savings? I notice people removing the
lid and putting in back 'skew' to let the over-boiling reduce, (wasting
heat) rather than turning down the power. A lot of people I have talked to
about this think that vigorous boiling cooks food faster. My own wife
thinks that.

>We are currently writing a paper to document these findings.

That is good news. Please keep us informed.

>During the cooking phase with the pot lid on, at the lowest
>levels of flame, the "efficiency" drops significantly.

I am suspicious that this effect might be device/stove related rather than
in principle. Can you comment? Where does the heat go if it is not into
the pot? Does the combustion efficiency reduce, perhaps, in the device you
use or are you using electric heat to simulate a fire?

>One of the keys here is to realize that we only care
>a little about the efficiency and we care a lot about
>how much fuel is consumed to cook dinner -- and these
>are not the same issue.

Well said.

>Based on this the key issue for potlids is the effectiveness
>of the stove at low flame, this includes turndown, stability
>of flame, emissions and a variety of other issues.

That is a sage summation. Good turndown with a long clean simmer is rated
highly in my region. It should simulate a propane stove.

I will try to get some PHU figures for low heats.

Regards
Crispin

From kmbryden at IASTATE.EDU Wed Mar 26 13:43:16 2003
From: kmbryden at IASTATE.EDU (kenneth mark bryden)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids
In-Reply-To: <1687512158.20030326180959@ecoharmony.com>
Message-ID: <WED.26.MAR.2003.124316.0600.KMBRYDEN@IASTATE.EDU>

At 06:09 PM 3/26/2003 +0000, Grant wrote:
>In my tests pot lids reduced overall efficiency by reducing water
>evaporation in the calculation of simmering efficiency, but reduced
>fuel consumed during simmering by a factor of three. From an emissions
>point of view, the use of a pot lid reduced total emission masses, but
>increased emission factors ? since emission factors are highly
>dependent on the quantity of fuel consumed. Reported here:
>http://ecoharmony.com/thesis/PhDch4.htm

I don't the think that pot lids reduce the efficiency during simmering by
reducing evaporation. But the jury is still out whether and under what
conditions they may reduce efficiency. I am hesitant to report tentative
results of work which is in progress and hence the conclusions may change.
So let me provide that warning here. At low simmering levels it appears
that in some cases the combustion gases are entrained with the steam from
the pot and this helps keep the hot gas flow attached to the side of the
pot with a higher velocity. As a consequence the efficiency with a pot lid
is lower. We have measured this lower efficiency and it is reproducible and
statistically significant. But I am speculating about the cause. We are
examining this issue using high fidelity modeling (CFD) to understand what
the exact cause is. I hope that we are able to report a more complete and
satisfying explanation by the end of the year.

On emissions the other factor to think about is that many stoves have much
poorer emissions performance at lower heat rates.

Mark

From crispin at NEWDAWN.SZ Wed Mar 26 11:08:19 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: Lids & Stove testing - Grant
Message-ID: <WED.26.MAR.2003.180819.0200.CRISPIN@NEWDAWN.SZ>

Dear Grant

>In any case if you do carry out the proposed tests, do
>make sure you randomize the order of tests and get
>someone to carry out the tests who has not already
>decided the outcome :-)

In this vein, I have tried only to report figures from other people rather
than my own (when there is someone to quote) however I found that when
people are 'testing my stove' they use situations that are quite different
and they get what I think are significantly different results. I find it
embarassing to make some or other claim - like a turndown ratio - and find
people saying, 'Well I tried it and I didn't get that much..." Looking into
this or similar issues with the other things I make usually leads me to
conclude that:
- they didn't know how to use it (training problem)
- they tested something else (mis-communication)
- there was something really different about how the test was carried out
(dissimilar methodology)

We make a lot of production machines that have to be assessed by the
customer who wants to know if they can make money with it. That has led to
us make 'achievable-by-an-ordinary-guy' claims for production, even though
we know an expert will get (far) more out of it. Then we don't disappoint
the semi-competent. Part of the technology always resides in the hands of
the operator, not the technology.

In stove testing there is, in my experience of it, a fair bit of tension
about performance claims and I have prefered to quote other people's
experiences. The problems I have are twofold: they don't get out what I
think is possible, and they use a variety of different methods. I have been
told by different people that 'that is the way to do a such-and-such test'
even though the tests they describe are not the same. One thing that was
widely agreed at the Vereeniging conference is that pots must not have lids
on or it misrepresents/screws-up the test.

Now I hear from people I understand and agree with, that pots should have
the lids on in all tests. Why then is there this gulf of understanding on
something so primal to the 'business' seeing that it was all discussed to
death in the '80's? Are people ignoring the conclusions (if any) or has
understanding improved over the years?

[GB-T] The purpose of the water boiling test is to compare
>two stoves in the (same) laboratory to make design decisions,
>and select promising designs for field testing.

I agree and I do that, but I wouldn't try to represent the stove to a
customer on that basis because it doesn't represent 'cooking'. That is all
I am getting at. I don't think there is a conflict, just that there appears
not to be agreement on a broad basis as to what constitutes a useful
(comparison) test of stove performance.

To give you an example, I sent a Vesto to a university Germany for 'testing'
which I thought was going to be emissions testing but which turned out to be
a rapid boiling test (I think). At least it was a boiling test, not a
'cooking test' as I proposed the other day. They did not receive any
demonstration of how to use the stove (as far as I know) and they did not
have a pot similar to what it was designed to use - apparently they are
banned in Germany. They put on a black pot from Zimbabwe with a long
handle. I think it is enamelled steel. It was quite a lot smaller in
diameter than the heat shield provided and the gap was 25 to 30mm from the
looks of the picture. These Zim pots are not obtainable here so I can't
check the figures or the performance.

The PHU for 1, 2, 3 and 4 litres in the pot was reported to be (approx) 15,
19, 22 and 26% (excluding the pot). Looking at the fuel used per test I
think it was overfilled but I don't know and the loading wasn't reported so
it is difficult to know. In other words, fuel management training might
produce a very different (better/higher) result.

So far so good and clear. At the end the report says that the stove could
not achieve 35% PHU and 26% was obtained.

Now that may seem pretty good for someone who doesn't know how to use or
load the stove correctly to get 26% but I find it misleading for me to claim
35% being possible when he can't obtain it and says so in something
'official'. The test does not reflect the fact that the pot clearance was
very large and probably not what it was designed to use, and basically, why
should it if it isn't 'usual' to do so?

This means that either there should be a 'standard' test and reproducable
result, or else a means of describing the claimed attainable PHU including
the pot and test type, like an SAE xxx test or something. Then I won't be
making claims that are not reproduceable by every Thomasina, Dick and
Harriet.

Someone told me they got 33% PHU (excl pot) cooking with dung. I believe
them. I can reproduce that, but not with a relatively small enamelled steel
pot, only with the pots we can get around here and for which the stove was
designed.

Thanks for listening.
Crispin

From crispin at NEWDAWN.SZ Wed Mar 26 14:40:14 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: RE Stove testing and lids - simmering efficiency
Message-ID: <WED.26.MAR.2003.214014.0200.CRISPIN@NEWDAWN.SZ>

Dear Mark and Grant

I picked up on the same point:

Grant said:
>In my tests pot lids reduced overall efficiency by reducing water
>evaporation in the calculation of simmering efficiency, but reduced
>fuel consumed during simmering by a factor of three.

Mark noted:
>I don't the think that pot lids reduce the efficiency during
>simmering by reducing evaporation. But the jury is still out
>whether and under what conditions they may reduce efficiency.

My take on this is that the efficiency it very slightly reduced by having a
pot skin temperature that is slightly higher due to the fact that there is
an insulating layer of air/steam on top of the 'food' under the lid. The
whole pot runs slight hotter. When the (insulating) lid is removed, the pot
will be slightly cooler and pick up a little more heat because of a higher
delta T, all other things being equal. This is a minor effect.

The bigger reason for a drop in efficiency is the method of assessing it -
that is, it is an artifact of the calculation method, not a fact about the
stove's efficiency which is probably higher when the lid is on.

When the steam is driven off the top of the water, and there is no lid, it
can drift away. This is interpreted by the calculation as 'missing water'
and therefore evidence of 'work ccomplished'. When there is a lid, esp when
the power is low, there is also evaporation of water, followed by
significant condensation on the underside of the lid. Some steam escapes as
well and is counted as 'missing water'.

Under the lid, water condenses and heat is yielded to the lid. This heat
travels through the pot lid which heats the air above and and again this
energy drifts away. However the water which transported the heat is not
'missing' and in Grant's calculation the loss to the air is being ignored,
even though there is (eventually) a transfer of heat from the lower part of
the pot to the air above the lid. This is in effect a 'heat pipe' and they
can be very efficient at moving heat from one place to another. Ignoring it
give misleading efficiency figures.

If the calculation of efficiency takes note of missing water and not of
heated air, then the formula will show an apparent drop in stove efficiency
when the pot is covered, because it is pretending that the work is not being
done, which is not true. The water is not missing but the heat is. It is
an artifact of the method of calculation, not a real drop in efficiency. If
you measured the heat gained by the air above the pot, the heat would
'reappear' and if added in, would probably show a higher efficiency than the
uncovered pot (as long as the pot was not at a roiling boil which is a
different case entirely).

The insulating effect of the lid would bring the heat transfer from the fire
to the pot down by some theoretical amount (probably not measurable) and
because it insulates the pot, conserve some heat by allowing any given
simmering level to be maintained with a slightly lower fire level. Heat
continues to be lost through the lid but because the efficiency calculation
does not include that, only lost water, it appears to drop.

Regards to all
Crispin

From Carefreeland at AOL.COM Wed Mar 26 20:46:51 2003
From: Carefreeland at AOL.COM (Carefreeland@AOL.COM)
Date: Tue Aug 10 18:30:19 2004
Subject: stove testing and lids
Message-ID: <WED.26.MAR.2003.204651.EST.>

Dear stovers,
Just a side note to this discussion. We agree that lids make quite an
efficiancy impact, on heat transfer while boiling water, on a stove. Just
imagine how much impact a lid has, on a hundred ton ladle full of MOLTEN
STEEL or IRON. I'll bet I could heat my house all winter on the heat wasted
in just a few minutes with the lid off. Now think of every other industrial
process you know of that wastes heat that way. What energy shortage?
Warm food, for thought,
Dan Dimiduk

From kmbryden at IASTATE.EDU Wed Mar 26 22:02:24 2003
From: kmbryden at IASTATE.EDU (kenneth mark bryden)
Date: Tue Aug 10 18:30:19 2004
Subject: stove testing and lids
In-Reply-To: <163.1df84457.2bb3b20b@aol.com>
Message-ID: <WED.26.MAR.2003.210224.0600.KMBRYDEN@IASTATE.EDU>

At 08:46 PM 3/26/2003 -0500, you wrote:
> Dear stovers,
> Just a side note to this discussion. We agree that lids make quite an
>efficiancy impact, on heat transfer while boiling water, on a stove.

Not quite... I think you need to reread my last note.

From kmbryden at IASTATE.EDU Wed Mar 26 22:15:58 2003
From: kmbryden at IASTATE.EDU (kenneth mark bryden)
Date: Tue Aug 10 18:30:19 2004
Subject: RE Stove testing and lids - simmering efficiency
In-Reply-To: <004501c2f3cf$a8795920$89e8fea9@home>
Message-ID: <WED.26.MAR.2003.211558.0600.KMBRYDEN@IASTATE.EDU>

At 09:40 PM 3/26/2003 +0200, Crispin wrote:
>Dear Mark and Grant
>
>I picked up on the same point:
>
>Grant said:
> >In my tests pot lids reduced overall efficiency by reducing water
> >evaporation in the calculation of simmering efficiency, but reduced
> >fuel consumed during simmering by a factor of three.
>
>Mark noted:
> >I don't the think that pot lids reduce the efficiency during
> >simmering by reducing evaporation. But the jury is still out
> >whether and under what conditions they may reduce efficiency.
>
>My take on this is that the efficiency it very slightly reduced by having a
>pot skin temperature that is slightly higher due to the fact that there is
>an insulating layer of air/steam on top of the 'food' under the lid. The
>whole pot runs slight hotter. When the (insulating) lid is removed, the pot
>will be slightly cooler and pick up a little more heat because of a higher
>delta T, all other things being equal. This is a minor effect.

I don't think the pot runs hotter - In fact I am certain it does not. There
is no difference with the pot lid on and pot lid off (as measured on a
number of pots and conditions in our lab). And so the temperature of the
water boiling in the pot is the same (as measured on a number of pots and
conditions in our lab). There are very few lids -- we haven't found any
that seal tight enough to raise the pressure inside the pot measureably.

>The bigger reason for a drop in efficiency is the method of assessing it -
>that is, it is an artifact of the calculation method, not a fact about the
>stove's efficiency which is probably higher when the lid is on.

No -- we have corrected for this and instantaneously calculate the
efficiency of heat transfer to the pot as well as the loss due to boiling

>When the steam is driven off the top of the water, and there is no lid, it
>can drift away. This is interpreted by the calculation as 'missing water'
>and therefore evidence of 'work ccomplished'. When there is a lid, esp when
>the power is low, there is also evaporation of water, followed by
>significant condensation on the underside of the lid. Some steam escapes as
>well and is counted as 'missing water'.

No -- The loss of water is the same if the power input is the same at high
or moderate power. The amount of water that condenses on the lid is only
equal to the amount of energy that can be removed by convective heat
transfer from the top of the lid the rest of the water is lost. At low
power a difference arises when the losses due to convection on the pot are
of the same magnitude as the energy lost by the boiling water. As a
consequence water can be kept boiling at lower power levels with the pot
lid on even though the efficiency is generally poorer at very low power
levels. But at any power level that an uncovered pot can be kept boiling
the losses will be the same with or without the pot lid.

>Under the lid, water condenses and heat is yielded to the lid. This heat
>travels through the pot lid which heats the air above and and again this
>energy drifts away. However the water which transported the heat is not
>'missing' and in Grant's calculation the loss to the air is being ignored,
>even though there is (eventually) a transfer of heat from the lower part of
>the pot to the air above the lid. This is in effect a 'heat pipe' and they
>can be very efficient at moving heat from one place to another. Ignoring it
>give misleading efficiency figures.
>
>If the calculation of efficiency takes note of missing water and not of
>heated air, then the formula will show an apparent drop in stove efficiency
>when the pot is covered, because it is pretending that the work is not being
>done, which is not true. The water is not missing but the heat is. It is
>an artifact of the method of calculation, not a real drop in efficiency. If
>you measured the heat gained by the air above the pot, the heat would
>'reappear' and if added in, would probably show a higher efficiency than the
>uncovered pot (as long as the pot was not at a roiling boil which is a
>different case entirely).

See the discussion above.

>The insulating effect of the lid would bring the heat transfer from the fire
>to the pot down by some theoretical amount (probably not measurable) and
>because it insulates the pot, conserve some heat by allowing any given
>simmering level to be maintained with a slightly lower fire level.

very much lower level.

>Heat
>continues to be lost through the lid but because the efficiency calculation
>does not include that, only lost water, it appears to drop.
>
>Regards to all
>Crispin

From pverhaart at OPTUSNET.COM.AU Thu Mar 27 00:28:06 2003
From: pverhaart at OPTUSNET.COM.AU (Peter Verhaart)
Date: Tue Aug 10 18:30:19 2004
Subject: Stove testing and lids - Mark
In-Reply-To: <001101c2f3a8$b8b1a3a0$89e8fea9@home>
Message-ID: <THU.27.MAR.2003.152806.1000.PVERHAART@OPTUSNET.COM.AU>

At 17:01 26/03/03 +0200, you wrote:
>Dear Mark
>
>Thanks for that.
>
> >In the heatup phase of cooking they can add some efficiency.
>
>It is this particular test which appears to be a litmus test of how 'good' a
>stove is among Stovers, even though cooks would appear to appreciate faster
>match-to-useful-heat times and less fuel required during cooking.
>
> >In the cooking phase if the stove /fire has good (very good) turndown they
> >can result in excellent savings of fuelwood.
>
>I am with you 100% there. Cooks claim that turndown is important.
>
> >However, if the same level of heat is applied to the pot in
> >both cases (pot lid on/pot lid off) there is negligible savings
> >with the pot lid on.
>
>Is this because there is a lot of water boiled out (more, or just as much)
>when the lid is on negating possible savings? I notice people removing the
>lid and putting in back 'skew' to let the over-boiling reduce, (wasting
>heat) rather than turning down the power. A lot of people I have talked to
>about this think that vigorous boiling cooks food faster. My own wife
>thinks that.

I sometimes skew the lid to prevent boiling over. Contact with ambient air
appears to decrease formation of foam.
Actually vigorous boiling takes longer, the reason is that more water is
needed to achieve the same result. I once tried to convince a lady of this
but I am not sure I succeeded.

Peter Verhaart

From crispin at NEWDAWN.SZ Thu Mar 27 02:59:30 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: RE Stove testing and lids - simmering efficiency
Message-ID: <THU.27.MAR.2003.095930.0200.CRISPIN@NEWDAWN.SZ>

Dear Mark

Thanks for the additional input. I understand the point about the
efficiency not changing when the pot is boiling vigorously. Power in, power
out, with or without a lid. I want to move on slightly. Can you clarify
something:

When you say:
>At low power a difference arises when the losses due to
>convection on the pot are of the same magnitude as the
>energy lost by the boiling water. As a consequence water
>can be kept boiling at lower power levels with the pot
>lid on even though the efficiency is generally poorer at
>very low power levels.

are you saying that when one remembers that the efficiency of the fire
itself (or the fire+stove combination) reduces as the power level is
reduced, then for any given simmer level, there is a net lowering of the
whole system efficiency because the gains from insulation provided by the
lid are less than the losses encountered when reducing the fire to
compensate for the lower power required to maintain that simmer level?

If so, then the reduction in efficiency found when adding the pot lid (at
lower, not higher powers, I agree) is an artifact of the stove, not a
principle of pot lids. If the stove were _not_ to reduce in combustion
efficiency when the power was turned down (apparently a 'given' in both your
and Grant's work), would you _still_ see a drop in overall efficiency when
the lid was added and the power reduced to compensate for the insulating. I
think this is an important question because it point out when we should look
for improvements.

I didn't quite understand this sentence:
>But at any power level that an uncovered pot can be
>kept boiling the losses will be the same with or
>without the pot lid.

Surely this only applies to higher, or as you said, medium to higher, power
levels? I proposed a few days ago that a meaningful test of a stove was to
boil a pot and then to measure how much fuel was required to keep it boiling
"with the lid off". Your point is that we could leave the lid on and it
wouldn't make any difference to that type of test, right? That would give a
'power phase' efficiency that was isolated from startup losses and to a
large extent, pot material and mass.

It appears to me that the simmering at low power is a useful test of low
power combustion efficiency, something that changes from stove to stove. If
one were to build a stove that did not reduce in combustion efficiency when
the power was turned down significantly (perhaps a gasifier?) that slight
drop in overall efficiency when using a lid might reverse.

At least it seems clear everyone agrees that lids help during the initial
heating of the pot and contents and therefore that testing and evaluations
relating to 'power-ups' should be done that way.

Regards
Crispin

From dstill at EPUD.NET Thu Mar 27 17:33:55 2003
From: dstill at EPUD.NET (Dean Still)
Date: Tue Aug 10 18:30:19 2004
Subject: ETHOS Stove Testing and Design Seminar
Message-ID: <THU.27.MAR.2003.143355.0800.DSTILL@EPUD.NET>

ETHOS Stove Testing and Design Seminar
June 2 ?6, 2003
Aprovecho Research Center
Cottage Grove, Oregon 97424
541 942-0302

Join Dr. Tami Bond, Ron Larson, Dr. Dale Andreatta, Dr. Larry Winiarski, and
others at Aprovecho for a week of sharing, experimenting and addressing
vernacular cooking stove topics. Let?s look at gasifying, charcoal making,
stoves in detail. Simultaneously, cooking stoves, like the Rocket, that are
designed to encourage initial ?complete? combustion will be tested. Using a
Enerac 3000 combustion analyzer, a HOBO CO sensor, eight thermocouples and
equipment to do Water Boiling Tests, the group will develop a shared
experience intended to foster the development of better stoves for the
needy.

Several topics of interest are:

1.) the role of preheated secondary air
2.) the effect of controlling primary air
3.) how a fan effects combustion

Anyone interested in stoves is very welcome to attend! Students are
encouraged to contribute. Let?s learn together and design better stoves! Low
cost accommodations are available in a nearby Tibetan Buddhist Monastery,
with local families, at camp grounds and in hotels in Cottage Grove. The
suggested donation for the week is $300 with a sliding scale. If the weather
permits, let's go sailing in the evenings, cook dinner using biomass. For
more details, to reserve a spot, please contact Dean Still at
dstill@epud.net or 541 942-0302.

From crispin at NEWDAWN.SZ Thu Mar 27 10:54:58 2003
From: crispin at NEWDAWN.SZ (Crispin)
Date: Tue Aug 10 18:30:19 2004
Subject: Efficiency test with the lid off at low power
Message-ID: <THU.27.MAR.2003.175458.0200.CRISPIN@NEWDAWN.SZ>

Dear Stovers

Well, I tried the lid-off low power 'boiling only' test to see what I got.
The pot was boiled first, the new wood added so that the whole test could be
done without changing the total amount of fuel in the fire. In my opinion
this is how to get the highest possible realistic PHU rating because all
work done goes into boiling water, not heating metal or clay.

Stove tested: Vesto, 275mm top opening
Pot used: 230mm aluminum flat-bottomed pot with a wire handle, 514 gm
without the lid
Gap between pot and stove body (275-230)/2 = 22.5 which is not optimal. A
250mm pot would have been better.
Heat shield: some tin foil hung loosely around the outside most of the stove
top lip extending to the level of the top of the pot (surrounding about 5/6
of it).

Method: The stove was placed on a 2gm electronic scale and zeroed. Wood
was added and lit, then the pot was put on and the water (over 3 litres) was
brought to a boil. The mass shown on the scale is then is the
wood+water+pot. Lifting up the pot gives the amount of wood remaining in
the combustion chamber. The pot mass didn't change during the test.

Reading - 514gm - remaining wood mass = water remaining in the pot.

Any time you want to do an efficiency calculation, you take a reading and
then lift the pot and take another reading then subtract the mass of the
pot.

I put in one piece of air dried wood weighing about 210 gm, dropping it onto
the remaining little fire that brought the pot to a boil. I let it get
established and then started the test. The pot was at a low boil/vigorous
simmer.

Time Mass
19:04 3728gm - 246gm wood - 514gm pot = 2968cc of water
Note: Vigorous simmer

19:08 Primary air closed to moderate the simmer

19:14 3360gm - 150gm wood - 514gm pot = 2696cc of water
Note: Low Simmer, primary air opened

19:24 3190gm - 120gm wood - 514gm pot = 2556cc of water
Note: Low Simmer, primary air open

19:28 3148gm - 110gm wood - 514gm pot = 2524cc of water
Note: Low Simmer, primary air open

19:34 3100gm - 104gm wood - 514gm pot = 2482cc of water
Note: Glowing coals, test stopped.

Note: Towards the end when the fire was nearly out, retained heat from the
combustion chamber (which weighs 1.3 kg) was probably driving the simmer as
the stove cooled with the dying fire.

It is probably most representative of the stoves characteristics to take the
first 20 minutes of the test while there was still reasonable no-lid
bubbling and 'real' simmering and visible flames from the chunk of wood.

Delta T (19:24 - 19:04) = 20 minutes
Fuel consumed (246-120) = 126gm x 16 MJ/Kg = 2,016,000 Joules
Water boiled off (2968-2556) = 412cc x 2260J/gm = 931,120 Joules
Percentage Heat Utilized (work done/fuel used) = 931,120/2,016,000 = 46.2%

It is very interesting to me that the second 10 miuntes of the test in which
the wood was burned at a lower rate, saw what appears to be a higher PHU. I
expect this because of the layout (heats the pot centre) and because of the
lower velocity of the hot gases past the pot giving more time to transfer
heat.

Second half of the test only:
Delta T (19:24 - 19:14) = 10 minutes
Fuel consumed (150-120) = 30gm x 16 MJ/Kg = 480,000 Joules
Water boiled off (2696-2556) = 140cc x 2260J/gm = 316,400 Joules
Percentage Heat Utilized (work done/fuel used) = 316,400/480,000 = 65.9%

If one estimates that the grate cooled from perhaps 450 deg to perhaps 300
during that time, retained heat from the earlier burning might have
contributed 1.3*450*150 deg = 87,750 J which means the efficiency was
actually:
Percentage Heat Utilized (work done/fuel used) = 316,400/(480,000+87,750) =
55.7%

If one considers that the wood was significantly charcoaled in the first
half and the charcoal burned in the second half, one can assume that perhaps
half the fuel used in the last half (30 gm) was charcoal meaning that it was
actually equivalent to:
(((30/2)*1.5)+30/2) = 37.5gm of wood = 600,000 J.

Note: Adding this consideration to the evaluation means the earlier 10
minutes should also be adjusted upwards by reducing the actual fuel used
because it was partly volatiles and not carbon.

This adjustment for possible charcoal burning reduces the efficiency to:
Percentage Heat Utilized (work done/fuel used) = 316,400/(600,000+87,750) =
46.0% during the second half of the test.

This is very close to the average for the whole test.

I conclude that there should be some consideration of whether wood is
gassing, or whether charcoal is burning when doing a test in a
semi-gassifier stove. The longer the test the more accurate the result will
be. The test should burn the entire piece of wood so as not to skew the
result.

Sincerely
Crispin

From ronallarson at QWEST.NET Fri Mar 28 01:57:27 2003
From: ronallarson at QWEST.NET (ronallarson@qwest.net)
Date: Tue Aug 10 18:30:19 2004
Subject: Forwarding Don O'Neal on Plancha Temperature Uniformity
Message-ID: <FRI.28.MAR.2003.015727.0500.>

Stovers and Ethos members

The following continues a discussion started in the last week on
achieving good (if desired) surface uniformity with a large flat metal
surface (plancha). We heard of work by Don O'Neal on an "inverted pyramid"
approach as one possible way to do this. Don has since sent some photos to
the Ethos list and to the stoves web site:

http://www.repp.org/discussiongroups/resources/stoves/

where Tom Miles has labeled this "JUTIAPA MOD" - which if you select takes
you to:

http://www.repp.org/discussiongroups/resources/stoves/Oneil/InvertPlancha.ht
ml

Tom has the complete version of the following discussion including the
figures which can't be shown here - so I insert some remarks to tie in to
the photos at the second web site above.

Don said

All:

I have just returned from an extended trip to Guatemala and see a lot of
interest in the inverted pyramid and some references to what HELPS is doing
in this regard. Here is an update.

1. The HELPS stove plancha is 14" by 28" and therefore has different
heating characteristics from the 22" square plancha tops. I didn't need
additional heat in the front or to the sides. Here was the original
configuration shown in my test lab. The gap under the plancha, front to
back, was 1 inch.

In this configuration the gases are collected in a slot in the back, to
prevent all gases going down the middle. Front and sides of the combustion
chamber were no problem.

(RWL): Two figures here. That on the left shows two identical original
stoves before applying the plancha. That on the right shows a graph with
two temperature vs time curves as described below.
Q1. Don - These straight line curves would tell us a lot about
efficiency if we knew the rate of fuel consumption (kg/hour or g/min). Do
you have any such information?
Q2. You talk about "holes" below - but I have an image of pots sitting
on the plancha. Can you tell us more about diameters and amounts of water
and how deep they penetrate the plancha if there is penetration.
Q3. Also tell us more about the pots (steel?, iron, aluminum?, weight,
height, diameter) and covering with lids (picking up another theme of
recent days). Could you readily run such curves alternating between lids
and no lids? Th use of such nice straight lines is very informative.
Anything special to say about your two temperature probes?

The curves show the heating rate on the front and rear pot holes. The
rate of heating on the back pot hole is about half that of the front. At
the green marker spike, the front pot starts to boil and the pots are
reversed. Back to front and front to back. The boiling pot, now on the
back pot hole continues to boil and the cooler pot, now on the front,
starts to heat at a rate approximating the original front pot. The women
seem to prefer a hotter area and a simmering area. In fact there was
little problem with this configuration until the ladies tried the 'Jutiaupa
Mod'.

2. This design was later changed to sort of an sort of a one-sided
inverted pyramid, although I never thought of it that way. Just a way of
shifting some of the heat to the back.

3. This was first done in Jutiaupa, Guatemala and has become known at
HELPS as the 'Jutiaupa mod'. Note in the right photo there is some shaping
of the pumas to direct more gases into the corners and that the ramp ends
under the back pot hole. There is still a one inch gap in front of and to
the sides of the combustion chamber and in front of the exhaust slot.

4. Word spread as all ladies liked it better. So much so that we went
back and retrofit all stoves in the field. This was a big effort but we
were interested in consistency of all installations. There are now 750
stoves in use with the Jutiaupa mod.

5. There is still a difference in heating rate front to back. Where
previously the heating rate in back was about 50% of the front, it is now
75% of the front. The front dropped a little and the back came up a
little. Test show that when considering both pots the efficiency is the
same. Efficiency test of just the front would obviously not be quite as
good.

Regards to All

Don O'Neal
HELPS International

(RWL): Don has three photos all nicely showing various aspects of this
partial "inverted pyramid" in which the use of strips welded to the bottom
of the plancha as recently described by Mark Bryden are replaced by
variations in the depth of the gap below the plancha.
Q4. You went to considerable expense to make this change. Can you
guesstimate what the cost was to take out the several baldosas and then
replace? Could you use/save some or all of the existing baldosas? The
baldosas are the ceramic tiles used for floors or roofs through out the
region - but these are specially made, I believe just for stove use - and
the interlock in a clever way.
Q5. Is there any way of quantifying the psychology with the women of
this difference in performance? How serious was the perceived gain? If
you had two types of designs, would/could/might a private sector system
have developed to modify the units?
Q6. If someone now went another step and modified further in some way
(or went back to the original) - how serious would that be perceived? Are
you discouraging such intervention? Who started this one and why?
Q7. Do you see any benefits for the rectangular shape plancha vs. the
square that others are employing?
Q8. If the surface of the plancha that was not being used was covered
with an insulation to prevent radiative and convective losses - do you have
any idea how much fuel might be saved and would/might it be worth the cost
and the time of the cooks to be manipulating thes "blocks" (which might be
volcanic material of the type noted recently by Rogerio)?
Q9. Please add anything else that members of these lists might need to
know to avoid problems that you have already overcome.
Thanks again for some very nice (and quantitative) insights on surface
temperature uniformity. Ron

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From tmiles at TRMILES.COM Fri Mar 28 22:01:41 2003
From: tmiles at TRMILES.COM (Tom Miles)
Date: Tue Aug 10 18:30:19 2004
Subject: [Biomass Cookstoves Notebook] 3/28/2003 6:46:27 PM
Message-ID: <FRI.28.MAR.2003.190141.0800.TMILES@TRMILES.COM>

Plancha stoves modifications for even heating and stove testing have been the live topics recently. We've added pages and links for:

1. Don O'Neal, Helps International. (Jutiaupa) Modifications to the Helps Plancha for better heat distribution
2. Don's Response to Ron Larson's Questions about Heating Curves for Plancha Stoves
3. Don O'Neal, Helps International, Updated Photos for the Cast and Mold Stoves
4. Piet Visser, BTG Cookstove.net, Links to Stove Testing Procedures: www.Cookstove.net! > Reports

--
Posted by Thomas Miles to Biomass Cookstoves Notebook at 3/28/2003 6:46:27 PM

From ronallarson at QWEST.NET Sat Mar 29 10:57:34 2003
From: ronallarson at QWEST.NET (ronallarson@qwest.net)
Date: Tue Aug 10 18:30:19 2004
Subject: Possible griddle burner
Message-ID: <SAT.29.MAR.2003.105734.0500.>

Lanny and all stovers:

1. Sorry for the delay in responding. Yours was just what I was looking
for. (Not sure about "spitballs" though (?))

2. To others, I recommend your site http://www.lanny.us/3br.html
and have these questions:

a. Below your last photo, you wrote: "When all 3 paths are left open It
smoked." I consider this a very important observation and wonder if you
or anyone can give an explanation.
Was this easily reproducible and repeatable and quick-acting? Lots of
smoke? A little?
Is there an easy way around this smoking problem when you have all
three open? Is this a question of doing more to keep the total air
restrictions similar as you vary the path options?

b. You also said a few sentences on: "The design needs high and low
air control and a longer fuel magazine."
I don't see how you will get air control here. Thinking of a fan? A
"flapper" valve in the three "pipes"?
Can you explain more why a longer fuel magazine is needed. Is this
related to the smoking problem?

c. You also said: "A later version split higher up allowing more
length for combustion." Is this something you would recommend? Is this
length issue related at all to the splitting - or a general observation?
Flames coming up too high now?

d. Also, lastly: "I nested this thing in some loose high temp
fiberglass insulation and it burns very clear." Can you tell us more about
this insulation. Cost? Any negatives?
Did the insulation change the character of the combustion? Anything to
be said about efficiency and your preference for steel over ceramic pipes?

Lanny - again very glad you are part of this list - lots of unexpected
past interesting work.

Ron

Original Message:
-----------------
From: Lanny Henson lanny@ROMAN.NET
Date: Tue, 25 Mar 2003 19:05:51 -0800
To: STOVES@LISTSERV.REPP.ORG
Subject: [STOVES] Possible griddle burner /Re: [STOVES] FW: [ethos] Fw:
justa pix

----- Original Message -----
From: Ron Larson <ronallarson@QWEST.NET>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Monday, March 24, 2003 8:21 PM
Subject: Re: [STOVES] FW: [ethos] Fw: justa pix

--------------------------------------------------------------------
mail2web - Check your email from the web at
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From ronallarson at QWEST.NET Sat Mar 29 11:17:23 2003
From: ronallarson at QWEST.NET (ronallarson@qwest.net)
Date: Tue Aug 10 18:30:19 2004
Subject: Griddle Cooking on the Camp Stove #6A
Message-ID: <SAT.29.MAR.2003.111723.0500.>

Lanny:

1. Again apologies for missing this one earlier.

2. A few questions on your photos:

a. Your inner "baffle" looks quite oval and off-centered in the first
photo, but is circular and looks maybe larger in the second. Are they the
same and how do you achieve circularity and centering?

b. You make some good points about the heat capacity of the griddle.
Any conclusions on whether yours is now correct or on best thickness,
etc. Could you turn the guage numbers into metric for us.

c. I was admiring the thermal characteristics of the waffle iron we are
using where I am staying (we don't use one at my home). Having two
surfaces for heat transfer is very nice - but probably not realistic for
the type of stoves we discuss. But I wonder if you or anyone has ever
tried an upper (maybe "swinging") "lid" that could serve as an insulator
when not in use for faster heat-up) but also as a way of cooking the top
surface simultaneously with the bottom.

d. I like the looks of your outer red insulating cover. Can you
describe that more? How much impact does it have?

Thanks again.

Ron

Original Message:
-----------------
From: Lanny Henson lanny@ROMAN.NET
Date: Tue, 25 Mar 2003 19:53:10 -0800
To: STOVES@LISTSERV.REPP.ORG
Subject: [STOVES] Griddle Cooking on the Camp Stove #6A

Lanny Henson

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From lanny at ROMAN.NET Sat Mar 29 19:39:22 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:19 2004
Subject: Possible griddle burner
Message-ID: <SAT.29.MAR.2003.163922.0800.LANNY@ROMAN.NET>

Ron and Stove Friends,
See below.
----- Original Message -----
From: <ronallarson@qwest.net>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Saturday, March 29, 2003 7:57 AM
Subject: Re: [STOVES] Possible griddle burner

> Lanny and all stovers:
>
> 1. Sorry for the delay in responding. Yours was just what I was looking
> for. (Not sure about "spitballs" though (?))
>
> 2. To others, I recommend your site http://www.lanny.us/3br.html
> and have these questions:
>
> a. Below your last photo, you wrote: "When all 3 paths are left open It
> smoked." I consider this a very important observation and wonder if you
> or anyone can give an explanation.
> Was this easily reproducible and repeatable and quick-acting?

LH- Yes, using any one hole worked well and you could quickly switch to any
hole. Two outlets worked if everything was hot but three did not burn clean.

Lots of smoke?

LH- Not a lot but enough to see.

> Is there an easy way around this smoking problem when you have all
> three open? Is this a question of doing more to keep the total air
> restrictions similar as you vary the path options?

LH- I think it needs a longer flame path before division.

> b. You also said a few sentences on: "The design needs high and low
> air control and a longer fuel magazine."
> I don't see how you will get air control here. Thinking of a fan? A
> "flapper" valve in the three "pipes"?

LH - 2 slide doors for combustion air control like the Camp Stove except one
above the Rocket shelf and one below the shelf.

> Can you explain more why a longer fuel magazine is needed. Is this
> related to the smoking problem?

LH- Room for charcoal, to hold long sticks more level. So you can close the
door on a short sticks.

> c. You also said: "A later version split higher up allowing more
> length for combustion." Is this something you would recommend? Is this
> length issue related at all to the splitting - or a general observation?
> Flames coming up too high now?

LH- The latest Rocket had a longer chimney and flame path with a
rectangular wye ("Y") on top for a "two burner stove top". For combustion
air control it has two slide doors. By building up some charcoal and
adjusting the air controls it got beyond red hot and orange hot closer to
yellow hot about 1000 to 1100 degC. The metal chimney crumbled after two
burns, I like it! I will use something more durable next time.
> d. Also, lastly: "I nested this thing in some loose high temp
> fiberglass insulation and it burns very clear." Can you tell us more
about
> this insulation. Cost? Any negatives?

LH- The fiberglass is just some material I salvaged and I nested the burner
in this insulation. It all fit perfectly in a metal lawn chair.

> Did the insulation change the character of the combustion? Anything
to
> be said about efficiency and your preference for steel over ceramic pipes?

LH- The insulation seemed to help. I use metal to prototype because it is
easy. More durable materials would be necessary for hot spots.
Lanny

> Lanny - again very glad you are part of this list - lots of unexpected
> past interesting work.
>
> Ron
>
>
>
>
> Original Message:
> -----------------
> From: Lanny Henson lanny@ROMAN.NET
> Date: Tue, 25 Mar 2003 19:05:51 -0800
> To: STOVES@LISTSERV.REPP.ORG
> Subject: [STOVES] Possible griddle burner /Re: [STOVES] FW: [ethos] Fw:
> justa pix
>
>
> Dear Ron and Stovers,
> You mentioned a griddle burner and a "V" shape. Well it sounds like
> something from the stove graveyard that may be a possible spit ball on
the
> ceiling so to speak. A multiple chimney rocket burner.
> http://www.lanny.us/3br.html about 90KB
> http://www.lanny.us/3br1.jpg a 26KB photo
> Lanny Henson
>
>
>
> ----- Original Message -----
> From: Ron Larson <ronallarson@QWEST.NET>
> To: <STOVES@LISTSERV.REPP.ORG>
> Sent: Monday, March 24, 2003 8:21 PM
> Subject: Re: [STOVES] FW: [ethos] Fw: justa pix
>
>
> > Stuart et al
> >
> > Thanks for the further discussion. Just a few more questions:
> >
> > 1. I was asking about avoiding baffles altogether - but rather using a
> > combustion region that instead of being of uniform cross-sectional area,
> > widens uniformly as one approaches the plancha - maybe even to the full
> > plancha width (apparently usually 22 inches). It seems that Don O'Neil
> may
> > have tried this and I wondered what his results were (or anyone elses)?
> > Have the stoves supported by TWP always had a "straight" combustion
> region -
> > as in all the Rockets I have seen?
> >
> > 2. I can conceive of a close-to-vertical central dividing surface that
> > might allow one to put most of the energy on one side of the plancha
> > (presumably away from the chimney - but not necessarily) or
alternatively
> > (by sliding top and bottom edges separately horizontally) try for a more
> > uniform temperature (for different types of cooking). (I am thinking of
> > something that would add a few bucks to the price. Anyone heard of such
a
> > scheme? (Think of a "Vee" in crosssection with a somewhat shorter
> > horizontally moveable "I" in between with the chimney on one side of the
> "V"
> > and the horizontal plancha across the top of the "V"
> >
> > 3. After my question about measuring efficiency on such stoves, I
> > remembered visiting the Ethiopian national stove lab (before it was
killed
> > in an unfortunate budget cutback maybe 10 years ago). I saw a woman
> > employee who spent the entire day making the big (60 cm) enjiras on
stoves
> > of different types. The efficiency measure was in kg of wood per kg of
> > enjira, I think (thereby not worrying too much about the number of
> enjira,
> > I recall - but the woman was keeping track of both and trying for a
> uniform
> > product). I wonder if the same measure wouldn't be valid for comparing
> > different plancha-type stoves. Any estimates by anyone on this FOM for
> > tortillas? Should be roughly comparable with the enjira number (which I
> > don't know - but might be able to find.
> >
> > Stuart - thanks for your strong support for all those thousands of
stoves.
> >
> > Ron
> > -----Original Message-----
> > From: owner-ethos@vrac.iastate.edu
> [mailto:owner-ethos@vrac.iastate.edu]On
> > Behalf Of Stuart Conway
> > Sent: Monday, March 24, 2003 4:24 PM
> > To: Ron Larson; Stoves Discussion List; Ethos
> > Cc: Richard Fox
> > Subject: Re: FW: [ethos] Fw: justa pix
> >
> >
> > Hi Ron et al,
> > Let me answer some of your questions and comments below:
> >
> > <snip>
> >
>
>
> --------------------------------------------------------------------
> mail2web - Check your email from the web at
> http://mail2web.com/ .
>

From tmiles at TRMILES.COM Sat Mar 29 20:31:29 2003
From: tmiles at TRMILES.COM (Tom Miles)
Date: Tue Aug 10 18:30:19 2004
Subject: Beehive report
Message-ID: <SAT.29.MAR.2003.203129.0500.TMILES@TRMILES.COM>

Sjoerd, Ron, Elk,

I've converted Sjoerd's report to HTML and linked it to the website so
that all should be able to access it. I added a table of contents and
updated some of the links and cost conversions. I also kept the pdf format
as an alternate for those who can manage the 1800 k file.

Find it from the main Stoves Website at
http://www.repp.org/discussiongroups/resources/stoves/

Tom

From lanny at ROMAN.NET Sun Mar 30 19:59:09 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:20 2004
Subject: Griddle Cooking on the Camp Stove #6A
Message-ID: <SUN.30.MAR.2003.165909.0800.LANNY@ROMAN.NET>

Dear Ron and Stove Friends
See LH- below
----- Original Message -----
From: <ronallarson@qwest.net>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Saturday, March 29, 2003 8:17 AM
Subject: Re: [STOVES] Griddle Cooking on the Camp Stove #6A

> Lanny:
>
> 1. Again apologies for missing this one earlier.
>
> 2. A few questions on your photos:
>
> a. Your inner "baffle" looks quite oval and off-centered in the first
> photo, but is circular and looks maybe larger in the second. Are they the
> same and how do you achieve circularity and centering?

LH-It is the same. It is just an oval shaped duct sitting over the burner
#6A, shown in the
http://www.lanny.us/cs6p.html 32k photo

> b. You make some good points about the heat capacity of the griddle.
> Any conclusions on whether yours is now correct or on best thickness,

LH- No conclusion about the thermal mass.
A tortilla has only about 16 or 17 grams of water to vaporize but 250 gr of
wet ground meat which is probably 90% moisture would have a 100 grams or
more of moisture to vaporize. I would think that you would want enough mass
to keep the temp from dropping too much but not so much mass that after
cooking you would have a lot of left over heat that is wasted.

> etc. Could you turn the gauge numbers into metric for us.

LH-
16 ga = .062 inches = 1.57 mm
10 ga = .140 inches = 3.56 mm

> c. I was admiring the thermal characteristics of the waffle iron we are
> using where I am staying (we don't use one at my home). Having two
> surfaces for heat transfer is very nice - but probably not realistic for
> the type of stoves we discuss. But I wonder if you or anyone has ever
> tried an upper (maybe "swinging") "lid" that could serve as an insulator
> when not in use for faster heat-up) but also as a way of cooking the top
> surface simultaneously with the bottom.

LH- That is exactly what I was thinking! A thermal mass on top, insulated
and hinged. One problem to solve is that metal plates tend to warp when
heated and may not stay flat enough to contact both sides of a thin
tortilla.
An insulated cover would help to heat faster and help store heat longer. And
how about a hole in the insulated cover for a pot to sit through?

> d. I like the looks of your outer red insulating cover. Can you
> describe that more? How much impact does it have?

LH- That is a 2 ply wrap of fiberglass fabric (welders blanket) to which I
added a 1 ply of aluminum foil as a air barrier. The outer insulation helps
in windy conditions and helps (the haybox effect) to hold cooking temps
longer.
I doubt that fiberglass fabric is going to be a common local material and
it does not insulate well anyway. So I need a more practical outer shell
insulation design.

Thanks for the excellent comments,
Lanny Henson

From lanny at ROMAN.NET Sun Mar 30 20:47:42 2003
From: lanny at ROMAN.NET (Lanny Henson)
Date: Tue Aug 10 18:30:20 2004
Subject: Griddle Cooking on the Camp Stove #6Aoops
Message-ID: <SUN.30.MAR.2003.174742.0800.LANNY@ROMAN.NET>

The photo should be http://www.lanny.us/cs6p.jpg a 32k photo. The oval
riser duct sits over this burner. The heat strikes the bottom of the griddle
and exits the bottom tray back to the chimney.
Lanny Henson

----- Original Message -----
From: Lanny Henson <lanny@ROMAN.NET>
To: <STOVES@LISTSERV.REPP.ORG>
Sent: Sunday, March 30, 2003 4:59 PM
Subject: Re: [STOVES] Griddle Cooking on the Camp Stove #6A

> Dear Ron and Stove Friends
> See LH- below
> ----- Original Message -----
> From: <ronallarson@qwest.net>
> To: <STOVES@LISTSERV.REPP.ORG>
> Sent: Saturday, March 29, 2003 8:17 AM
> Subject: Re: [STOVES] Griddle Cooking on the Camp Stove #6A
>
>
> > Lanny:
> >
> > 1. Again apologies for missing this one earlier.
> >
> > 2. A few questions on your photos:
> >
> > a. Your inner "baffle" looks quite oval and off-centered in the first
> > photo, but is circular and looks maybe larger in the second. Are they
the
> > same and how do you achieve circularity and centering?
>
> LH-It is the same. It is just an oval shaped duct sitting over the burner
> #6A, shown in the
> http://www.lanny.us/cs6p.html 32k photo
>
> > b. You make some good points about the heat capacity of the griddle.
> > Any conclusions on whether yours is now correct or on best thickness,
>
> LH- No conclusion about the thermal mass.
> A tortilla has only about 16 or 17 grams of water to vaporize but 250 gr
of
> wet ground meat which is probably 90% moisture would have a 100 grams or
> more of moisture to vaporize. I would think that you would want enough
mass
> to keep the temp from dropping too much but not so much mass that after
> cooking you would have a lot of left over heat that is wasted.
>
> > etc. Could you turn the gauge numbers into metric for us.
>
> LH-
> 16 ga = .062 inches = 1.57 mm
> 10 ga = .140 inches = 3.56 mm
>
> > c. I was admiring the thermal characteristics of the waffle iron we
are
> > using where I am staying (we don't use one at my home). Having two
> > surfaces for heat transfer is very nice - but probably not realistic for
> > the type of stoves we discuss. But I wonder if you or anyone has ever
> > tried an upper (maybe "swinging") "lid" that could serve as an insulator
> > when not in use for faster heat-up) but also as a way of cooking the top
> > surface simultaneously with the bottom.
>
> LH- That is exactly what I was thinking! A thermal mass on top, insulated
> and hinged. One problem to solve is that metal plates tend to warp when
> heated and may not stay flat enough to contact both sides of a thin
> tortilla.
> An insulated cover would help to heat faster and help store heat longer.
And
> how about a hole in the insulated cover for a pot to sit through?
>
> > d. I like the looks of your outer red insulating cover. Can you
> > describe that more? How much impact does it have?
>
> LH- That is a 2 ply wrap of fiberglass fabric (welders blanket) to which
I
> added a 1 ply of aluminum foil as a air barrier. The outer insulation
helps
> in windy conditions and helps (the haybox effect) to hold cooking temps
> longer.
> I doubt that fiberglass fabric is going to be a common local material and
> it does not insulate well anyway. So I need a more practical outer shell
> insulation design.
>
> Thanks for the excellent comments,
> Lanny Henson
>
>
>
>
>
> >
>

BioEnergy Lists: Improved Biomass Cooking Stoves

March 2003 Biomass Cooking Stoves Archive