[Stoves] Philips Stove. Was Re: Jatropha press cake as a fuel

[Paul van der Sluis]

Dear Paul A., Tom M.

I haver made quite a lot of models and several sizes of stoves. The 
current size is based on optimizing combustion cleaniness and user 
feedback.
Many types of wood have been used, both here in Europe and in India. The 
biggest difference I have seen is that Indian wood used is of low quality, 
probably with
lot's of bark and gives more ashes than what I am used to.

Doing the same combustion experiments in Tom Reeds stove is more difficult 
because the thermal mass of that stove is much smaller (at least the one I 
have seen).
The addition of the wood should not lower the combustion chamber 
temperature to below about 400 Celcius because in that case the secondary 
flame will be
extinguished and emissions rise dramatically (at least until the flame 
re-ignites)


The main effect from the air from the lower holes is to prevent charcoal 
built up. The charcoal will 'vaporize' according to"

C + 1/2 O2  --> CO

And this CO will burn at the secondary air holes. This can clearly be seen 
as a typical blue-pink flame as soon as the wood pyrolisis itself has 
stopped and the more or less
yellow flame has disappeared. Note here, that a yellow flame can surely 
burn cleanly (just like a wax candle burning)

Of course part of the air will hit wood. That is also why increasing the 
size of the primary airflow holes increases the thermal power of the stove 
and the emissions.

Using the stove in the traditonal top-lit manner is not recomended because 
in that case the heat cannot reach the thermoelectric generator. 
For start-up there is one small rechargeable battery. After about 5 
minutes the thermoelectric generator takes over to power the fan and 
recharges the battery for the next run.


Regards,

Paul.

 

Dr. P. van der Sluis 
Philips Research Laboratories Eindhoven