[Stoves] side fed = gassification , no se

[Crispin Pembert-Pigott]

Dear Richard

>With the  briquettes in a simple side fed rock stove , such as developed by
Rok Oblak and replicated widely, I think we are pretty close! 

Yes, this is on the right track. If people can't operate the stove for
continuous periods they will reject it. We can't count on people being
desperate all the time as an adoption mechanism.

For the briquettes, the holey version seems to be the most suitable answer.
It is possible to have parallel fires in a plancha stove with a standard
sized small briquette that can also be used in smaller stoves. I think we
should consider making them a lot taller using the 'extrusion' method I
mentioned re the marula nuts, but without the change in dimension. The
compression should be two staged. It would give a continuous extrusion. This
approach greatly reduces the labour and speeds the process of forming the
units. There is a direct parallel with oil seed pressing. The old presses
used a contained that was filled and pressed. Then it was removed, emptied,
refilled and pressed again. In practise it was necessary to press the seeds
three times (for marula). It took longer to dig out the nuts than fill the
container. The 'episodic' press approach has a closable plate at the end
which is left closed until the oil (or water in this case) is expelled. Then
the plate slides back and the mechanism is operated again to eject a portion
of the formed briquette. In the oil press, the pressing motion of the piston
is vertically down.

For chopped fuel, a diagonal hopper and cross draft fire seems best. There
are working examples of that layout. 

There is a new patent on a method of getting heat from the bottom of a
hopper and combustor into a cooking plate which could be applied in a
commercial model.

Experiments with crossdraft fires in Mongolia showed an 80% reduction in PM
emissions without really improving the stove at all. That was amazing. There
is a lot of room for improvement and innovation.

Regards
Crispin