[Stoves] Wet wood better?

[Kevin Chisholm]

Dear Crispin

"A stove should be optimized to operate with the fuel it is likely to 
encounter in the area of implementation (Grant B-T's point)."

Grant's point is so fundamentally obvious to a methodical Stove Designer, 
that it should not even need mentioning. A stove designed for one fuel type 
is very unlikely to give similar results when operated with a different fuel 
type.

The work proposed by Frank to categorize the various fuels could be very 
helpful to stove designers, buyers, and operators.

Imagine the simplicity of a situation where stove performance was rated 
based on fuel types defined by Frank's work.  Imagine the following:

"This stove has been designed to operate on fuel types 53, 75 and 91. When 
on these fuels, it will give an efficiency of 63% and emissions of XX grams 
per hour. It will operate on fuel types 24, 28, 37 and 84 with no more than 
a 10% deterioration in efficiency and a 12% deterioration in emissions....."

Look at how simple life would be for Stove Buyers, NGO's, etc.

Best wishes,

Kevin

----- Original Message ----- 
From: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com>
To: "Stoves" <stoves at listserv.repp.org>
Sent: Friday, December 29, 2006 12:35 PM
Subject: Re: [Stoves] Wet wood better?


> Dear David W
>
>>Makes sense to us, and would give a little bit more "real conditions" to
>>the lab testing.
>
> This is a very important issue because if a stove is designed to burn real
> wood and tested with something else, obviously the results will not be
> compatible.  The issue is immediately before us as we go into ETHOS with a
> view to establishing performance benchmarks for emissions and stove
> performance.
>
> If it is true that moist (15%) wood has lower emissions than very dry 
> wood,
> this might only be true for certain stove types (like the ones tested to 
> get
> that result) or it may be true for all stoves, or all stoves of a certain
> group like non-gasifiers.
>
> Grant Ballard-Tremeer is very much in favour of real world emissions 
> testing
> and I certain lean in that direction myself.  There is on problem with 
> that
> /in extremis/ whch is that labs do infact develop stoves and we need to 
> have
> a handy measure of design changes.  We can't go to the field to check each
> little tweak.
>
> If it is possible, under normal circumstances, to get wood down to 15%
> moisture by following the advice of stove programme trainers (i.e. keeping
> it out of the rain and store it for a month or two) then we are onto
> something valuable.
>
> It may be that certain stoves, for example all spoon-fed stoves like a
> gasifier that is refuelled with a few pellets or a Rocket stove or a Lion
> stove in which the fuel is fed in every few minutes, perform best with 
> very
> dry wood, or at least are no bothered by very dry wood.  This is certainly
> not the case for a stove like a Tsotso, Vesto, gasifier or even a 
> livingroom
> fireplace.  They do not tolerate very dry fuel well at all.
>
> If a stove is optimised for emissions and thermal performance using fuel
> that is not available in the field, obviously there will be a 'failure to
> meet expectations', especially on the emissions front.  A stove like a 
> Lion
> which has measured air flow would produce a lot of smoke if the fuel were
> suddenly to bo so dry that it nearly explodes into a cloud of wood gas.
> While one could argue that the operator should compensate by withdrawing 
> the
> fuel that is burning too quickly while watching the smoke level, this 
> misses
> the point.
>
> A stove should be optimised to operate with the fuel it is likely to
> encounter in the area of implementation (Grant B-T's point).
>
> I have a feeling we with labs are all going to have humidors with a lot of
> wood inside....
>
> Regards
> Crispin