[Stoves] is this new?

[Crispin Pemberton-Pigott]

Dear Marc

 

>That cutaway is beautiful! Great example of "let the product speak for
itself"

That shows the importance of having a plasma cutter handy.

Since seeing counterflow in action, I understand exactly what you're
describing with the air flows. 

Good. A picture is worth 100 descriptions.

>I didn't understand your emphasis on keeping the flame near the bed with a
"descending burner" until this paragraph:

>>The secondary air is send across the surface to keep a deck of flame going
at the height of the holes. This obviates the need for adding a circular
disk at the top to 'keep the flame going'. Adding a 'concentrator' as Paul
calls it takes more material and moves the fire too far away from the heat
of the pyrolysis bed leading to unwanted flame-outs from time to time. 

Well, try building a couple of pyrolysers and see how they go. There is a
good reason gasifier buildings are always standing by with a box of matches
to toss into their latest smoke bomb.


>What's on the "to-do" list for this class of design, Crispin? Are you
looking to push it into other applications? Apply the principles to improve
existing design? (like you mentioned with advancing the Anglo SupraNova)

The application of the combustion method is potentially widespread. I think
it solves a lot of problems that otherwise require tinkering by the cook
(which they hate).  The Anglo SupraNova incorporates the secondary air
control rather easily because it is not a conventionally shaped charcoal
burning chamber. It can be improved further, I believe. We are just
'trying-it-out' with a dozen or so to see what the populace thinks about it.
The lighting cone is being introduced at the same time so there is a
double-whammy.

The stove GERES is presently teaching people how to build is very similar to
the Anglo Supra and can be modified to the same benefit. The advantage of
the metal+clay body is that the clay can break and it still stays together
(which is why a Jiko has the same arrangement). This is not a very
forward-thinking approach however. If the clay is properly constituted and
the firing correctly done, there should be no need for a metal body, unless
that portion is re-useable in future. The metal is expensive.

We will of course be sharing the developments of the Anglo/LS/Thai Bucket
stove with anyone who is interested. Cecil Cook and I will try to work with
GERES and the WB to create a regional product development collaborating
group, possible through the S4Group which concentrates on local initiatives
and local experts. I believe the whole stove can be made from clay for under
$1 and I will try that in March to see if thermal expansion of the inner
shell breaks the outer shell. I expect a fully developed clay version to
out-perform a metal Vesto.

There is a guy in Maputo who (illegally) copies the Vesto using a clay body
with a clay air tube and a metal combustion chamber. It is very efficient.
The outer wall never gets warm. It is a great charcoal stove (which is the
dominant fuel).

Regards

Crispin

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