# 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.
Write-up is coming :) Putting in some effort so that it's a useful resource for folks in the future. Marc Paré B.S. Mechanical Engineering Georgia Institute of Technology | Université de Technologie de Compiègne my cv, etc. | http://notwandering.com On Sat, Mar 17, 2012 at 1:55 PM, Crispin Pemberton-Pigott < [email protected]> wrote: > 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 <[email protected]> > wrote:**** > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > >
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