[Stoves] Efficiencies for the rich and poor.

ajheggie at gmail.com ajheggie at gmail.com
Fri Oct 4 14:40:58 MDT 2013


[Default] On Thu, 3 Oct 2013 14:54:21 -0700,"Frank Shields"
<frank at compostlab.com> wrote:
>The results show a rapid decrease in weight that
>then stabilizes around the 400c and mostly completed at 450c. Using
>Thermogravimetric analysis (TGA) on biomass can separate the fuel into two
>distinct and repeatable fractions. The one fraction between ambient
>temperature to 450c we know will be used during cooking as once this
>restively low temperature is reached it has volatilized. It needs no oxygen
>from outside and gets it all from the fuel to form a gas then secondary air
>to completely combust.  

My understanding is that the pyrolysis is only weakly exothermic
between 330 and 450 but the reactions driving this are mostly cracking
of pyrolysis products within the bits of wood. There may be small
amounts of free oxygen from air in interstitial spaces of the wood
that will react with nascent char and produce a small part of this
heat but any oxygen already bound to the wood molecule will not
contribute to oxidation overall as it is has already given up its bond
energy.

AJH



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