[Stoves] Fuel Testing

[AJH]

On Wed, 04 Oct 2006 10:12:51 -0500, psanders at ilstu.edu wrote:

>Assuming 20% moisture (so that the numbers are both high enough and also
>realistic for many fuels in many areas), then the energy would only be 80% of
>18.6 MJ/kilo = 14.9, and then the loss of 0.54 MJ from the water results in
>14.4 MJ.  That is a significant loss.

Yes I calculate the same
>
>However, can we disregard (for the moment, at least) that moist wood is only
>very slighly larger in physical size (volume) than is dry wood?

Yes, in general wood's volume remains about constant down to 30%mc and
then loses up to 10% as it reaches bone dry, so for most purposes you
can neglect the change in volume.

>  If dry and
>moist wood are the same size, then the container of fuel (1.1 liter size in my
>case) could have the same full measure of wood chips (or fireballs, etc) AND
>include the extra weight of the 20% moisture.  This leads to saying that the
>moisture causes only 2.9% reduction in the useful thermal energy, when dealing
>by volume, not by weight.

Yes except if it's on a wet weight basis of 20% mc I get 3.6%, I get
2.9% if the mc is measured on a dry weight basis.


In deference to David Whitfield's comments about armchair experts I
have avoided commenting on the validity of testing methods as I have
never worked in a laboratory nor have I experience in the field of
dependence on biomass cooking.

AJH