[Stoves] Thickness of flame front

[frank]

Dear Andrew,

>
>It begs the question how long would a 2.5cm piece of wood have to
>dwell above the pyrolysis front to reach an equilibrium with the
>temperature of the off gas?
>  
>
If the combustion zone height is constant (say 4 cm) the 2.5 cm wood 
would be zero at the top of the zone and 2.5 at the bottom as the zone 
moved downwards. A triangle.  That would mean half is already burned in 
that area at one time (I think) and the rate it moves down depends on 
the 1) oxygen it gets 2) cooling  effect  from air moving the heat up 
and away (conductivity)  based on narrowness of the void space and 3)  
how fast the surface can get up to temperature  with heat being drawn 
into the particles (size of particle).  At least that is the way I am 
looking at it today.

>I hope you're keeping a record of all these questions because one day
>we may have a couple of weeks in a lab together...
>  
>
If you are ever in this area you are very welcome to vortex a test tube 
or two or three.... I would enjoy showing you around and we could design 
some tests.

>AJH
>
>
>  
>
Regards
Frank



-- 
Frank Shields
Soil Control Lab
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