[Stoves] Excess air and combustion efficiency - the data

[Crispin]

Dear Friends

For those who want to really bend their calculator buttons, here as numbers 
from a cold start and hot start of a STOws Concrete Cooker.  One problem is 
that when the EA goes above 1000%, it cannot be shown on the screen so the 
real EA is indoubt at 1000%.

The boiling point is marked.  After the water boils, the fire is reduced 
substantially.  If the water gets near the allowable minimum of 3 deg below 
boiling, the fire is rekindled.  The effect on EA and CO/CO2 ratio is 
pronounced and immediate showing that a hot high-mass stove has considerable 
powers to reduce emissions.

During the simmer it was often the case that only the charcoaling embers 
were required to keep the pot hot, and thus the numberes look more like a 
charcoal stove than a wood stove.  In practise it is likely that this is 
what people will do (leave it alone), rather than tend the stove constantly 
to maintain a very small fire.  At this early stage it is not clear what the 
effect on CO/CO2 ratio would be of choking the air supply tight(er) during 
simmering.

Have fun!

Regards
Crispin

STOws Concrete Cooker, 5 litre water boil and 45 minute simmer.  Fuel: Wood 
ignited by paper.

Cold Start
      340% 4.3%
      345% 4.3%
      447% 5.2%
      583% 10.3%
      284% 2.9%
      288% 3.3%
      344% 4.3%
      755% 13.3%
      333% 2.8%
      583% 12.7%
      656% 14.1%
      525% 7.5%
      382% 4.0%
      438% 4.2% Boiling
      618% 7.5%
      600% 6.3%
      568% 5.9%
      538% 4.0%
      618% 4.4%
      1000% 11.7%
      618% 3.3%
      875% 4.9%
      913% 8.5%
      989% 7.9%
      1000% 17.1%
      1000% 11.2%
      1000% 10.6%
      1000% 9.2%
      1000% 8.4%
      840% 4.3%
      438% 2.8%
      1000% 8.5%
      1000% 10.5%
      1000% 9.2%
      1000% 6.0%
      800% 3.0%


Hot start

      389% 5.9%
      438% 8.3%
      512% 7.0%
      296% 2.4%
      389% 3.4%
      292% 3.8%
      288% 1.9%
      583% 7.8% Boiling
      656% 12.2%
      840% 7.2%
      913% 3.9%
      1000% 10.0%
      1000% 10.0%
      1000% 9.4%
      1000% 9.4%
      1000% 10.6%
      1000% 13.1%
      1000% 11.8%
      1000% 9.6%
      1000% 7.0%
      1000% 4.5%
      356% 2.1%
      565% 4.4%
      840% 18.0%
      1000% 4.5%
      1000% 11.0%
      1000% 9.8%
      1000% 8.3%
      1000% 8.0%
      1000% 6.7%



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