[Stoves] TLUD stove design change

[Crispin Pemberton-Pigott]

Dear Frank

Many thanks for you report. Can I ask that you observe something: I have
noticed many times that if the number of particles occupying the space
(width/diameter) of the container is less than 5 (bigger particles) things
do no go well.

So I have this idea that the particle diameter and in a way the space
between them (recognizing that flakes are different from balls) is a major
determinant of the quality of the burn. I have settled on the number 6. If
the particle size is larger than 1/6th of the diameter, things are not going
to work well. This applies to TLUD and downdraft stoves.

In order to burn large chunks in a small stove, a completely different
approach is needed, basically making a refuellable retort which is described
by your suggestion.

It seems the Dia/PSize is fundamental for many types of simple burner.

Regards
Crispin