[Stoves] Belonio burner top on TLUD stoves was Re: radiant heat capture, total heat measurement
rongretlarson at comcast.net
rongretlarson at comcast.net
Fri Mar 16 16:32:23 CDT 2012
Crispin etal (couldn't get to "Alexis")
1. I had a small off-list exchange a few days ago with Andrew H. who also thought (on this list) that Paul Olivier had obtained a pre-mixed flame. The exchange went this way, with my talking to Andrew:
" Below you describe Paul's flame as premixed. Unless something has changed (Paul?), I believe the flamelets are of the diffusion type - all secondary air is above the "Belonio burner".. "
Paul responded a few days ago.
"Ron, you are right.
Air comes into contact with the gas only after it exits the burner holes.
Air does not come into contact with gas before it exits the burner holes.
Pau l "
2. It now seems critical to better understand everything about the secondary air flow, which obviously is different from Belonio's. Paul responded a few days ago on this - but I didn't follow his answer. This is to request a bit more from Paul - since that detail MAY have been the cause of the halving of boil-time. (I can think of several other causes.) I am interested in the gap dimensions - that are probably in the drawings sent to his machine shop. I probably could find these in the "stoves" archives, but am sure it will be easier for Paul to repeat that construction detail - and to affirm that the tests were with exactly this and wth no other changes..
But I also hope Paul can make a more direct comparison new test between his and the earlier Belonio boil-time data. Paul, is that new test possible for you?
Thanks in advance.
Ron
----- Original Message -----
From: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com>
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>, "Paul Olivier" <paul.olivier at esrla.com>
Cc: zong at ilstu.edu, "Belonio - Philippines" <atbelonio at yahoo.com>, "Corey Berman" <bizurman at gmail.com>, "Hugh McLaughlin" <wastemin1 at verizon.net>, "Bob Fairchild" <solarbobky at yahoo.com>, 'Alexis', "Chua He" <chuazh at gmail.com>
Sent: Friday, March 16, 2012 10:56:09 AM
Subject: Re: [Stoves] Belonio burner top on TLUD stoves was Re: radiant heat capture, total heat measurement
Dear Paul A
I think quite a bit more experimentation is needed before copying the top
end of Alexis' burner. The evolution is that it was not a premixed flame and
the structure was built with that in mind. The change to a premixed flame
was not matched by a change in the structure. The result is that there is a
very high excess air rate passing through the underside and emerging by the
pot. This has the effect of heating a lot of air an lowering the gas
temperature beside the pot.
I feel that a 30% improvement in heat transfer efficiency can be achieved by
addressing this issue.
I have noticed that stove builders fall roughly into two groups: those who
build high neat transfer efficiency stove bodies but with mediocre
combustion, and those who make really good combustion but neglect the detail
of getting good heat transfer. In some cases there is a sort of blind
adherence to the idea that a fuel is 'clean' and there is no need for
either. 'Clean burning means efficient,' which is nonsense.
We should all be paying a lot of attention to both aspects of stove
building: efficient combustion and efficient heat transfer. One does not
automatically derive from the other.
Regards
Crispin
-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul S.
Anderson
Sent: Friday, March 16, 2012 6:07 PM
To: Discussion of biomass cooking stoves; Paul Olivier
Cc: zong at ilstu.edu; Belonio - Philippines; Corey Berman; Hugh McLaughlin;
Bob Fairchild; Alexis; Chua He
Subject: [Stoves] Belonio burner top on TLUD stoves was Re: radiant heat
capture, total heat measurement
Dear all,
Paul Olivier commented: (full message is still below, with link to a
photo)
> ..... which has always led me to wonder why the Belonio burner hole
> pattern was not adopted on natural draft units.
> If a burner housing were added, I think the unit I experimented with
> would work much better.
Paul O. raises an excellent point. I think that the moderate complexity of
the Belonio hole pattern and secondary air inlet (contrasted to simple
concentrator hole) has kept me and probably most others from experimenting
with it. Perhaps we incorrectly associated it too much with the forced air
(Fan Assisted = FA) aspects of Belonio's rice husk gasifiers.
Very little is known about the tops of TLUDs except that some amount of
constriction is needed to force the mixing of air and gases.
I hope that the engineers (such as Bob Fairchild and student
engineers) and others who are now working on TLUD stove issues will
seriously consider the Belonio top and related enhancers of combustion of
the gases.
Paul (Paul A.; not to be confused with Paul O.)
--
Paul S. Anderson, PhD
Known to some as: Dr TLUD Doc Professor
Phone (USA): 309-452-7072 SKYPE: paultlud Email: psanders at ilstu.edu
www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf (excellent ref.)
My website specific for TLUD information: www.drtlud.com = www.DrTLUD.com
Quoting Paul Olivier <paul.olivier at esrla.com>:
> Kevin,
>
> You say:
> *# OK!! A 50% reduction in boiling time is very significant.
> What can you now tell us that will enable us to apply it to other stoves
> and combustion conditions?*
>
> I once did an experiment in which I made the 150 Belonio about half its
> original height.
> I then filled it with chunks of wood and put a Belonio burner on top.
> This was a natural draft unit without a fan.
> This is what it looked like:
> http://dl.dropbox.com/u/22013094/150%20Burner/Image2097.jpg
> But looking back on this, I see that there were so many problems with this
> burner,
> even aside from the fact that it had no burner housing.
>
> You raise an interesting question, though, which has always led me to
wonder
> why the Belonio burner hole pattern was not adopted on natural draft
units.
> If a burner housing were added, I think the unit I experimented with would
> work much better.
> The central problem that I see with a natural draft unit is an uneven
> upward flow of primary air.
> At times too much CO2 is created, and some burner holes lose their flames.
> Also I would imagine that the inlet of primary air has to be strictly
> control to get a consistent outlet of gas at the burner.
>
> A natural draft TLUD is very complicated,
> and I truly marvel at those who get them to work on such a broad variety
> of fuels.
>
> Thanks.
> Paul
>
> Thanks.
> Paul
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