[Stoves] Particles and particle types (was Charcoal Making Stove)

[Tami Bond]

Hi all,

Unorganized collection of random thoughts:

If you like you can call these things 'aerosols' which means a solid or 
liquid particle suspended in a gas.

Some particles are not visible to the eye. Black particles seem harder 
to see than white particles, especially when you are in an enclosed 
environment. Very small particles do not interact with light efficiently 
(but they don't have much mass).

I think of 3 kinds of particles
1. ash (the solid fireflies) which are so large that they are only 
lofted when there is a lot of velocity (fans or buoyancy).
2. white smoke-- unburned fuel, or fuel that was transformed a bit 
before being volatilized
3. black smoke-- made in a flame-- quite near the flame front. Flame is 
buoyant and thus draws volatile-laden air through it, removing white 
smoke but making black smoke-- not in equal proportions, as some of the 
white smoke (unburned fuel) gets consumed to make non-particulate products.

I guess it's not as simple as black and white, but that's a first cut.
Smoke particles are mostly carbon-- white or black-- at least according 
to our measurements. We use absorption, scattering, 'elemental/organic 
carbon' analysis to differentiate. I have also measured composition with 
XRF (x-ray fluorescence) and ion chromatography; didn't see much. But 
remember that this was dry, clean wood, and wet, nasty wood could be 
different.

You can combust unburned fuel by keeping it *really* hot and mixing 
well. Time, temperature, turbulence.
Harder to get rid of black smoke below ~1200 C; it just doesn't oxidize 
fast enough. There is combustion literature on this topic.
Dilution quenches everything. If you're down to 500 C, probably won't do 
much of anything, so you have to get it at the flame front.

cheers,
Tami