[Stoves] Re Alexis Belonio article

[Burnham-Slipper Hugh]

> We have tested a Chinese stove that uses steam injected into the
combustion
> chamber. The jets of steam create superior mixing which results in cleaner
> burning. It may be that the steam also makes hydrogen but I think that
this is a
> side issue. It's the improved mixing without using electricity that seems
to me
> to be the important result.

When wood burns, the char initially burns with (primary?) oxygen to give carbon monoxide, because there generally isn't enough oxygen at the char surface to burn to completion. 

C + 0.5 O2 --> CO

The carbon monoxide then moves away from the fuel by diffusion and convection and burns with (secondary?) oxygen to give carbon dioxide. 

CO + 0.5 O2 --> CO2 

The rate of the carbon-monoxide-to-carbon-dioxide reaction is given by: 

[CO] x [O2]^0.25 x [H2O]^0.5 x 2.24e12 x exp(-1.8e8/RT)

where [CO], [O2] and [H2O] are concentrations of carbon monoxide, oxygen and water vapour. R and T are the gas constant and temperature. Presumably this Chinese stove burns cleaner because there is a lot of [H2O] kicking about, and all the carbon monoxide can burn to carbon dioxide with relative ease (releasing extra heat at the same time). If that is the case, injecting a jet of air won't make as big an impact as injecting a jet of steam... or am I talking out of my hat?

Happy Easter all, Hugo. 




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