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<div class="moz-cite-prefix">Dear Marc, Julien, and all Stovers,<br>
<br>
There has been some good discussion (and hands-on work) about the
combustor on the TLUDs. Here are some miscellaneous comments.
<br>
<br>
1. Marc wrote:<br>
<blockquote type="cite">(the paper says that the hole of the
concentrator ring should be 70% of combustion chamber diameter.
In terms of area, it means about 50% combustion chamber area)</blockquote>
I think that is mis-stated. Most concentrators holes are about
half of the diameter of the full ring (fuel chamber diameter).
For 6 inch diameter fuel chambers, the size most used for holes is
3 inch diameter (plus or minus half inch is fine). That hole is
only 25% of the area of the whole disk. Dean Still (at Stove
Camp) said that his is with a 4" dia chamber has a 2" hole (if I
remember correctly). <br>
<br>
2. Marc also wrote:<br>
<blockquote type="cite">I never liked (for cooking purposes) the
single-thick flame that comes out of the concentrator ring that
use most of the TLUD's designs, because you get a narrow
over-heated spot in the bottom of the cooking pot, and in a
result of that, you don't get a good heat distribution in the
pot.<br>
<br>
I made a new "diffuser" burner, which gives a circular flame
area, instead of a single one.<br>
<br>
<a href="http://youtu.be/mhl6tt2A4T0">http://youtu.be/mhl6tt2A4T0</a><br>
<br>
<div id="inlineImage0" style="display: inline-block"><span
contenteditable="true"></span><span contenteditable="true">
</span></div>
<br>
Anyone knows any other works on this aspect?<br>
</blockquote>
<br>
The use of an annulus (ring) of gases for combustion (vs. the
central flame of concentrators) was in the very first item ever
written about what is now known as TLUD stoves. See:<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.drtlud.com/wp-content/uploads/2013/12/woodgas-stove-reed-larson-1996.pdf">http://www.drtlud.com/wp-content/uploads/2013/12/woodgas-stove-reed-larson-1996.pdf</a><br>
<br>
And that stove has difficulties with maintaining flame around the
entire annulus when the supply of gases is not high. What I
think I have been reading by the recent researchers is to have
something like a concentrator and then an annulus, ALL below the
pot. I hope that can help solve the issues.<br>
<br>
Paul<br>
<pre class="moz-signature" cols="72">Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a>
Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
On 8/25/2014 2:04 AM, Marquitusus wrote:<br>
</div>
<blockquote cite="mid:DUB127-W427BA97716075785FE230CA8DF0@phx.gbl"
type="cite">
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<div dir="ltr">Hi Julien,
<div><br>
</div>
<div>Thank you for the info. and the paper.</div>
<div><br>
</div>
<div>Yesterday I was applying all this information to my new
burner design. I realized that, according to this paper, the
holes should be bigger if I wanted not to reduce the draft. I
assumed my new burner act as the typical "concentrator ring",
and make its empty area to be the same size as the paper
recommends (the paper says that the hole of the concentrator
ring should be 70% of combustion chamber diameter. In terms of
area, it means about 50% combustion chamber area)</div>
<div><br>
</div>
<div>What I can say since now, regarding the firsts test with
this new burner, is that apart from the distribution effect,
it mantains the mixing effect (pyrogas+secondary air) of the
classical concentrator ring. I have observed that the flames
coming out of the secondary air entrance holes, tend to
concentrate in the center of the burner, just in the bottom of
the area wich is not open. Then they make a spin movement, and
finally find its way through the empy areas.</div>
<div><br>
</div>
<div>I suppose this movements in the bottom part of the burner,
very near the base of the flames, contribute to the mixing
process. But, as you say, I haven't tried it under difficult
conditions, so I cannot say it would be desirable in all
conditions.</div>
<div><br>
</div>
<div>Following your thoughts, I also think we should have to
find the optimal distance between the ring and the secondary
air intake. In this sense, <span style="font-size: 12pt;">I
think that it should be desirable to mantain this distance
as short as possible, in order to not losing heat through
the sides. If we put a long mixing/expanding tube (chimney),
we will have a very large emitting heat area. If we find
there is no alternative, then we'll have to think about
insulating all this area. That is the reason why I try to
mantain chimneys as short as possible. What do you think
about it?</span></div>
<div><span style="font-size: 12pt;"><br>
</span></div>
<div>All the best,</div>
<div>Marc</div>
<div><br>
</div>
<div><br>
<br>
<div>
<hr id="stopSpelling">Date: Sun, 24 Aug 2014 09:56:59 -0400<br>
From: <a class="moz-txt-link-abbreviated" href="mailto:winter.julien@gmail.com">winter.julien@gmail.com</a><br>
To: <a class="moz-txt-link-abbreviated" href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</a><br>
Subject: [Stoves] Trying new burner for TLUD's<br>
<br>
<div dir="ltr">
<div>Hi Marquitusus;</div>
<div><br>
</div>
<div>Your burner looks like an interesting idea. It is
worth checking to see if it will operate under difficult
conditions, such as low pyrogas production from fuel
> 12% (wet wt.) moisture. </div>
<div><br>
</div>
<div>I have been testing various options such as annular
rings for pyrogas, concentrator disks (not rings cf.
Anderson and Wendelbo), and swirls. The problems with
burners emerge with the fuel I described above. What I
find is that (1) objects over the top of the TLUD
reactor that prevent secondary air descending toward the
fuel bed, and (2) swirls generated near the base of the
gas flame, don't work well under difficult TLUD
operating conditions. I am going to post the results of
experiments on these shortly.</div>
<div><br>
</div>
<div>The conclusion I have reached (for the burners I have
tested) is that it is best not to interfere too much
with the bottom of the gas flame.</div>
<div><br>
</div>
<div>However, once the gas fame is well established,
modifying it higher up in the burner to create
turbulence or spread the flame could be a good idea.
Therefore, I think your idea has merit. If you haven't
already done so, you may want to experiment with the
distance your disk is above the secondary air intake,
i.e. is there sufficient space for the gas flame to
expand.</div>
<div><br>
</div>
<div><br>
</div>
<div>Based on the work by </div>
<div><br>
</div>
<div>Birzer, C; Medwell, P; Wilkey, J; West, T; Higgins,
M; MacFarlane, G; Read, M. 2013. An analysis of
combustion from a top-lit up-draft (TLUD) cookstove.
Journal of Humanitarian Engineering, 2(1). </div>
<div><a moz-do-not-send="true"
href="http://www.ewb.org.au/jhe/index.php/jhe/article/view/11"
target="_blank">http://www.ewb.org.au/jhe/index.php/jhe/article/view/11</a></div>
<div><br>
</div>
<div>you should check to see that the size of your disk,
relative to the burner outer diameter, doesn't slow down
the TLUD reaction too much.</div>
<div><br>
</div>
<div><br>
</div>
<div>All the best,</div>
<div>Julien.<br clear="all">
<br>
-- <br>
</div>
<div dir="ltr">Julien Winter<br>
Cobourg, ON, CANADA<br>
</div>
</div>
<br>
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</blockquote>
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