[Terrapreta] heat energy: stoves vs. thermo biopiles

[Duane Pendergast]

          Sean,

 

As I recall from tests done with a "bomb" calorimeter as part of my
engineering education, HHV referred to the amount of energy available when
the steam portion of the products of combustion of a dry fuel is condensed.
LHV referred to the energy available if the steam is not condensed.

 

Wikipedia confirms I've not lost all.

 

http://en.wikipedia.org/wiki/Higher_heating_value

 

That's a little different concept than that of using energy to drive off
moisture pre-combustion - and I see Jeff Davis has already responded to this
effect. Oh well - repetition is the best teacher.

 

Duane

 

-----Original Message-----
From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Sean K. Barry
Sent: November 23, 2007 11:51 PM
To: jeff0124 at velocity.net; terrapreta
Subject: Re: [Terrapreta] heat energy: stoves vs. thermo biopiles

 

Hi Jeff,

 

Yes, I think you are right.  The lower heating value (LHV) is used versus
the higher heating value (HHV) because there is usually energy lost in
driving water out of the feedstock before any energy can be used from the
combustion.  This assumes that 100 C heat is not usable.  However, if there
is a use for relatively low quality heat (e.g. green house warming in cold
climes), then 100 C might be usable.  

 

Also, if a feedstock is dry then the LHV and HHV are closer in practice.
The HHV is, I believe, actually measured as heat generated from the
combustion of "bone dry" (0% moisture content) feedstock.

 

Regards,

 

SKB

----- Original Message ----- 

From: Jeff <mailto:jeff0124 at velocity.net>  Davis 

To: terrapreta <mailto:terrapreta at bioenergylists.org>  

Sent: Friday, November 23, 2007 8:16 PM

Subject: Re: [Terrapreta] heat energy: stoves vs. thermo biopiles

 

 

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