[Stoves] RE: Charcoal Rocket

[Crispin at newdawn.sz]

Dear Dean

If the dilution is known, what is it?  For example, how much oxygen is in 
the same sample?

>From that, the excess air ratio can be calculated and as there is little 
hydrogen in the charcoal, an estimate of the CO2 can be calculated from the 
missing oxygen or else it can be hydrogen compensated as well.

If the sample was not drawn from the flame (ensuring that there is no nearby 
air diluting the sample) I still don't see what you can determine from a CO 
reading in ppm in diluted air.  Air that came through the stove or air from 
the room?

The effect of the insulated chimney might be to first pull a lot of excess 
air through (giving a low initial ppm reading) followed by all the fuel 
trying to burn at once (the diameter being too small to supply what is 
needed = high CO) followed at the end by the fuel burning down (getting out 
of the way) and allowing a high excess air to pass through again, diluting 
the CO and giving a low ppm reading.  None of that tells us how good the 
combustion was, not even how diluted the sample was.

The stove in the video looks like a case of too much fuel burning in the 
middle of the cook without adequate air.  If there were adequate air 
supplied one would normally expect to see a shortened flame.  The long flame 
and high CO indicates very low oxygen available.

The normal CO emission from a pretty clean-burning has the inverse of the 
profile you describe: high at first when the combustion is poor (lighting), 
low when there are some volatiles or else when it is still really hot, and 
high again at the end as the cold incoming air chills the coals and quenches 
the flames.

I think it is essential to have the same test with a CO/CO2 ratio so we 
would be able to determine if the tall thin chamber is doing what needs to 
be done.

Best regards
Crispin


----- Original Message ----- 
From: "Dean Still" <dstill at epud.net>
Sent: Friday, June 23, 2006 2:00 AM
Subject: RE: [Stoves] RE: Charcoal Rocket


Dear Crispin,

The CO levels are under a hood in which the dilution is known. In this way
ppm can be compared and a mass of pollutant per weight of fuel determined.

Best,

Dean




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