[Stoves] Belonio burner top on TLUD stoves was Re: radiant heat capture, total heat measurement

Crispin Pemberton-Pigott crispinpigott at gmail.com
Sat Mar 17 01:55:03 CDT 2012


Dear Alexis and Paul

 

Thanks so much for the very open discussion and open design of the burners.
Alexis, when we met in Thailand you mentioned that you have switched to a
premixed flame and if you recall we did talk a bit about the top end of the
version of the stove you demonstrated.

 

Is it correct that you are now using a premixed flame? I have been in
extensive conversation with Paul O about the burner for some time and it
seems at present to be a blend of premixing with secondary air and as Paul
says, some tertiary air for the final burnout.

 

The difference in performance that Paul mentioned and which got some much
discussion going about heat transfer from the hot dome could have at least
three quite different origins and there is a lot of merit in tracking down
the difference. The first might be that the structure under the pot on
Paul's present configuration is much more closed than the one I saw in
Thailand. That could account for all the difference in the boiling time. A
second possibility is the reduction in excess air either through the burner
where flames are present or between the flames and the final departure of
the pot and stove structure, by which I mean the outer ring. Until the hot
gases leave the pot and vent into the room, the air present in that gas
stream is technically part of the combustor. If there is a lot of cold air
entering the region under the pot, then it is counted as excess air in the
heat exchanger.

 

Paul, thanks for putting the pictures of the development work you are doing.
It is helpful for those who would like to work on stoves with minimal
equipment to see how things work and what has been tried. It saves a lot of
reinventing.

 

With regard to the heat transfer from a radiant dome, Marc has been doing
some calculations which I hope he will post here when he is confident in the
method. That should settle the question as to whether or not a large
increase in performance can be obtained by changing hot, relatively non-IR
radiant gas into IR emitted from a wide gauze surface.

 

It is well worth remembering that because a flame is pale blue in the
visible range, that does not tell us what it is emitting in the IR which is
invisible to human eyes. Looking through a translucent flame is not really a
measure of emissions of heat. If you point an IR gun at a flame it will
register a high temperature, even if it is as inaccurate as an unshielded
thermocouple.

 

I agree with the others that the discussion about heat transfer has been a
good exploration of the subject. I appeal to Marc not to hide his light
under a bushel. These discussion also need numbers and methods so the
reality of things becomes widespread.

 

Regards

Crispin

 

 

++++++

 

Alexis,

Here is the drawing of your burner:
http://dl.dropbox.com/u/22013094/150%20Gasifier/Drawings/005.pdf
Here is the drawing of the burner housing:
http://dl.dropbox.com/u/22013094/150%20Gasifier/Drawings/006.pdf
The housing is not easy to make without large pressing equipment.

The housing is placed over the burner.
The two parts are welded together at the four points where they touch.
http://dl.dropbox.com/u/22013094/150%20Gasifier/Boiling/IMG_1024a.JPG

446 stainless, as the drawings suggest, is too expensive.
Making both parts in cast iron could be considered.
But cast iron normally involves a considerable thickness.

I foresee a third part that fits above the burner housing.
This part is embedded within the counter-top.
This third part restrains the flow of excess air, and it shields the flames
from wind.

Thanks.
Paul

On Sat, Mar 17, 2012 at 9:16 AM, alexis belonio <atbelonio at yahoo.com> wrote:

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