[Stoves] comparative water boiling test

[Paul S. Anderson]

Stovers,

Jean-François' comments help us understand the specific CWBT 
(Comparative Water
Boiling Test).  But he also points out the usefulness of having ANY test that
is used just to make LOCAL or INTERNAL comparisons when decisions need to be
made.  The simple test can be adequate and appropriate.

The complexities of the WBT (and some other tests) stem from our desire to be
able to make comparisons of data from diverse locations.  And therein lies the
problem.  Even with a clearly defined test, there are differences from 
at least
two sources:  the fuels and the testing equipment.

I do not remember ever having seen comparative test results from 2 different
locations.  We have had 2 or even 3 sets of testing equipment present at a
single location (Stove Camps 2005 and 2006) so that we can say that the
different sets of equipment give comparable results.  But where are the data
sets from different locations that can be displayed side by side?  Stove
testing is done at Aprovecho's lab.  What other data have ever been laid out
next to those results?  Even most of the comparative data from 
Aprovecho's work
is still seen only as drafts, and the test results from Stove Camps 2005 and
2006 cannot be directly compared.

And consider the issue of fuels.  Aprovecho uses one type of wood for its
testing, and that is important for its sets of data.  But nobody else is using
that same type of wood (kiln-dried, what species?).  And others are not likely
to try to use that specific fuel, or to find it in their locations.  When Tami
and Chris go to Honduras, they do not do the stove testing with the same fuel
as is used at Aprovecho.

I arrive at two conclusions:

1.  We should do like Dr. Rozis suggests and do not worry about what fuel you
are using in the testing as long as your own sets of data are based on a
fully-described and consistent fuel type(s).  __IF__ further 
comparisons become
important, the true experts can help us compare a kilo of wood chips from
tree-type XX at 20% moisture versus a kilo of sticks from tree-type YY at 8%
moisture versus a kilo of fireballs (or briquettes) of material ZZ at 14%
moisture.  However, most of us would say "a kilo of sun-dried woody biomass is
about the same everywhere, but add a little or subtract a little 
"fudge-factor"
depending on moisture and any special characteristics of the biomass."

2.  We should not get hung up on these great emissions tests.  Nice if you can
have them done, but once your specific TYPE of stove has been measured for
emission a few times, you can pretty well know what the emissions will be like
in future testing.  So then you can focus on fuel consumption and heat 
transfer
and cook-related issues and other issues using the fuel that you 
determine to be
representative of the local fuel.  Of course, if your type of stove is 
lousy for
emissions, you might want to question why you are doing what you are doing.

Note:  There might be three "camps" of Stovers who do serious testing.  
One camp
is focused on fuel consumption ("save the forests"), a second camp is 
focused on
emissions ("IAP/health and Global Warming"), and a third camp wants to do both
fuel consumption and emissions.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson


Quoting Jean-François Rozis <rozisjf at club-internet.fr>:

> Dear Crispin,
>
> I read by chance the comment you made concerning the comparative 
> water boiling test, happy at the begining to have some exchange on it 
> and after disapointed to see some misunderstanding and confusion..
>
> So I will try to answer step by step:
> - goal of this test, only for field laboratory stove, just to improve 
> one stove or compare two stoves in correlation with specific local 
> cooking habits. No interest for me for having international test for 
> that, objective is to reduce sources of errors (different pots, fuel 
> specificity, local environment, complicated "modus operandi"..), same 
> place , same starting time, same pot, same fuel, same qty of fuel, as 
> simple to conduct as possible.
> Which one will perform better, that means with same quantity of fuel 
> will make more useful job (heating and water evaporating)
>
> - so I hope you agree with the interest for field developer of this test??
>
> - If yes, ok  it's just a problem of formula.
>
> - no need to add in calculation energy for maintaining stove pot 
> heat, loss energy and not useful for me, and when you make the 
> difference between stove with same pot, this amount is thus 
> eliminated so forget it (I saw kirk Smith also has taken it out for 
> the international WBT)
>
> - influence of cook, not evaluated in this test, only of course in 
> field test. Iif we have to maitain one test, for sure we will use 
> only field test (please a simple and comparative one of course), but 
> to see if I put higher pot rest, lower combustion chamber,.. what 
> will happen, hopefully I have not to build one hundred stoves and to 
> disseminate these ones in the field to see if I am right or not, for 
> that I need a laboratory test telling me I'm in the good way or 
> not..The final prototype will be of course validated in the field and 
> only at that time I could tell I success..
>
> - so the CWBT I presented is an indication valuable for Cambodia but 
> to be adapted for local cooking habits of course..In cambodia, saving 
> time, having for same fuel qty more power to the pot is the good way, 
> So I simplify the calcualtion in that way, evaporating water is in 
> that case useful energy proving I can cook faster so obtaining 
> approval from end user..
>
> - in other case, if you are sure to have certain power to not 
> overpass (long and lower simmering by instance), so  you can adjust 
> the simmering level (fix the power, by adjusting the quantity in fine 
> of water evaporated, same in the two stoves to be compared), so don't 
> go to DGIS to obtain formula just compare the total time to use the 
> fixed amount of fuel. The ratio will give you idea of potential fuel 
> saving, the longest lasting the better is in that case..I have to 
> precise I compare stove with same way of giving heat to the pot, not 
> one where pot is totally sunk in the stove, other only heating bottom 
> part.
>
> it's not the scenario to reproduce in each country it's the approach 
> to compare stove to be reproduced,
>
> so following this philosophy I'm sure we can write a final 
> description of this CWBT you can use in your context...
>
> to be continued
>
>
>
>
> ------------------------------------------------------------------------
> Jean-François Rozis
> Tél: 0467643816
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>



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