[Terrapreta] heat energy: stoves vs. thermo biopiles

[Sean K. Barry]

Hi Duane,

Ah yes, you and Jeff are quite right.  My mistake.  HHV contains the energy in the steams

Regards,

SKB
  ----- Original Message ----- 
  From: Duane Pendergast<mailto:still.thinking at computare.org> 
  To: 'Sean K. Barry'<mailto:sean.barry at juno.com> ; jeff0124 at velocity.net<mailto:jeff0124 at velocity.net> ; 'terrapreta'<mailto:terrapreta at bioenergylists.org> 
  Sent: Saturday, November 24, 2007 6:39 AM
  Subject: RE: [Terrapreta] heat energy: stoves vs. thermo biopiles


            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<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 Davis<mailto:jeff0124 at velocity.net> 

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

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

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




-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/terrapreta_bioenergylists.org/attachments/20071124/2b89ef8a/attachment.html