[Stoves] RE Stove testing methods

[Crispin Pemberton-Pigott]

Dear Steve

>...Grams of manure can be
>mostly rock and grams of wood can be mostly water.
> We need grams of a type of fuel or 'cooking energy'
>(whatever that is).

In my view the heat energy of the fuel should be de-rated by the amount of 
heat it takes to heat and boil away the water in the fuel.  The reason this 
is better than using dry wood is that the moisture affects how stoves work 
and it represents reality (which is good).

When you say 1 kg of wood, it is 850 gm if it is 15% water on a wet weight 
basis.  It is only reasonable that the actual heat in the wood be used when 
calculating the work done.  It is not 85% of the mass x the heat content of 
the fuel per Kg. The evaporation of the 15% also has to be taken into 
consideration because it is significant.

I agree with keeping it simple, so trying to get a tiny difference in heat 
content based on chemistry is not going to help much.  Nearly all biomass 
(dry) falls into a narrow band of 19-19.5 MJ/Kg with the major exception 
being pine at about 21.  No problem, put a heat content/Kg cell on the 
spreadsheet.

My approach is to work out how much of the dry fuel was needed to boil off 
the water. That is left was used to cook.  This most closely approximates a 
test with utterly dry wood without the attendant problems (or benefits).

Regards
Crispin