[Stoves] Excess air

[Crispin Pemberton-Pigott]

Dear Andrew

 

I will keep it short so you can access it.

 

>I was only addressing the definition

 

Agreed.

 

>What you are are seeing is vagaries of the way measuring equipment makes
assumptions about how the sensor reacts to the exhaust species and produces
an output.

 

That is what we assumed right from the start and it turned out not to be the
case. I hoped it was an instrument issue. It is a formula issue.

 

So I researched how that formula is supposed to work and does work, but not
for rocket engines. If not for rocket engines, why would it work for rocket
stoves?  :) 

 

So the real-real answer is that EA represents available O2 as if it were
air. No problem that is the definition. But to get the right answer it has
to be a % of the O2 actually required at the time.

 

What is required at the time changes with the chemistry at the time. That
chemistry can be directly measured using gas analysers.

 

Interestingly, for the same level of O2 in the stack, the EA is different
under different chemical conditions. Complex pyrolysing conditions provoke
all sorts of strange chemistry so the chemically balanced approach is
required, actually. For a given device, the best combustion tends to take
place under a certain EA level, but this varies (a lot) between devices. The
BLDD6 coal stove works best with 30% EA which is a very low value and really
surprised me. I would have guessed that was not possible.

 

Regards

Crispin

 

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