[Stoves] Thickness of flame front

[AJH]

On Fri, 04 Jan 2008 13:25:32 -0800, frank wrote:

>Wondering if there is a formula or educated guess or general rule as to 
>the thickness of the primary combustion zone in a TLUD? If the fuel 
>particles are of a large diameter (say 2.5 cm) with lots of porosity I 
>would think the thickness would be greater than if it was a small 
>diameter (rice hulls) or having the pour space filled with fines. What 
>volume of fuel is always burning is what I am trying to get at.

As I differ from others in thinking how a tlud device functions I
doubt there will be much agreement but I consider it to be a surface
effect, as such it will be a very thin layer limited by the surface
shape and lack of turbulence in the primary flow.

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?

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...

AJH