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Roberto and Kirk and all,<br>
<br>
Sorry for addressing a previous message to Kirk instead of to you.
So now my congratulations go to you for some very nice work!!!<br>
<br>
I like to see the whole configuration, as you have shown. That is
very important, and some results are only evident when several
components are functioning together.<br>
<br>
At the same time I tend to divide the configuration into components
to see them separately. Please correct me if I do not have them
well understood. Some components are:<br>
<br>
1. You have a concentrator disk/ring/top. What is different is
that you do NOT have any secondary air entering under the
concentrator. Interesting. So the gas flow is concentrated, but
without any (or without much) flaming of pyrolytic gases. As it
passes through the constriction and enters more open space, that is
a form of the Venturi effect. Improvements using cones or other
shapes are possible. (Continue)<br>
<br>
2. You have secondary air entering laterally above the
concentrator, and you are getting a good flame.<br>
<br>
3. When I see blue flames, I immediately suspect considerable
char-gasification (without pyrolysis). Please confirm that you
have raw biomass being pyrolyzed while you have the blue flame.<br>
<br>
4. Chimney: If the chimney is BEFORE (that is, usually below) the
pot, I like to call that a riser or an internal chimney, to
distinguish it from a commonly called chimney that is drafting AFTER
the pot.<br>
<br>
5. In either case, increasing the chimney will increase the natural
draft, which causes negative pressure (sucking) to PULL the gases
along (usually upward). One force of pulling that is impacting two
"pullable" elements: the primary air (that impacts the creation of
the combustible gases) and the secondary air (that impacts the
combustion of those gases).<br>
<br>
6. How that one pull is divided between the two entries of air is a
critical issue in TLUD stoves (and other stoves also). If BOTH
primary and secondary air are basically unrestricted (we know there
are channels and holes and fuel blocking, etc, but basically
unrestricted), the system tries to reach an equilibrium. But if it
pulls more on primary, it will make more gases and those gases will
need more oxygen (more secondary air) that might need to be from the
surrounding air, such as when a tall tongue of flame needs more air
than what can come in through the stoves manufactured secondary air
holes/slots/etc.<br>
<br>
7. So that is why it is so important to have a way to control
(restrict) the primary air. That is, when a tall chimney is
sucking strongly, most of that sucking will be available and used to
bring in secondary air through the intended secondary air entry
holes. Strong secondary air entry will cause the flame to be
LOWER, which is good because of better mixing and so that the pot
can be closer to much more of the flame (and not suspended up high
above a tall tongue of flame that can cause soot deposits). <br>
<br>
I suspect that many readers already knew what is written above.
(and some that did not know it still do not know it because they do
not read such long messages..<span class="moz-smiley-s1"><span> :-)
</span></span>..). Sorry, I got carried away.<br>
<br>
************<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<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>
<div class="moz-cite-prefix">On 10/8/2015 7:00 AM, Roberto Poehlmann
wrote:<br>
</div>
<blockquote
cite="mid:CAK_QYTz_Q+xZ8Rz2BbJA2-S-3-_bno3CckTA8vArxHNjA+F7xg@mail.gmail.com"
type="cite">
<div dir="ltr">
<div style="font-size:12.8px">Hi Kirk,</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Maybe i have named the top of the
combustion chamber with the wrong word (concentrator ring).
The combustion chamber has on top a 3 inch hole, and no
secondary holes inside the combustion chamber below the
concentrator ring.</div>
<div style="font-size:12.8px">The 3 inch hole "concentrate" the
smoke to the tube burner.</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">When the primary air control is
wide open, i can obtain a good flame with a taller internal
chimney to increase draft. Another way to increase secondary
air flow without a chimney is to add a fan.</div>
<div style="font-size:12.8px">The experiment, with a taller
chimney, also make me doubt about the importance of the
venturi effect versus the draft of a chimney. With a normal
TLUD burner (Peko Pe or Champion stove for example) you can
also have a short flame with a taller chimney.</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Another way, as you say, is to add
more than one burner.</div>
<div style="font-size:12.8px">I have made sometime ago, an
experiment with 4 similar burners on top of a 18 liter
chamber. The problem i had, is that always a burner draft
"lose" vs a stronger draft of another burner. The weakest
burner acts like a primary air control, and i never had a
"positive" draft for all of the burners at the same time. If i
restrict the weakest burner, another burner take the place
with negative draft.</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">The solution is to put a fan at
the primary air control, like Paul Olivier did, or with the
subdivision of the combustion chamber in 4 independent
chambers, each with his own burner on top. All of the 4
independent chambers can "share" the same primary air control
below.</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">I have no equipment to test
particulates or gases. The equipment are very expensive for
me. I am not a stove constructor (yet). But i thing the stove
would have very good results. Maybe you, Julian or Crispin can
contruct this burner and make some measurments to test it.</div>
<div style="font-size:12.8px">I have made some variations of the
tube, with distinct sizes and holes configurations, and i
found this is the best configuration for now (best looking
flame).</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Thanks for the photos of the
control valve. Maybe i will construct something similar.</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Here are some photos of the same
burner (tube and cone) and the same beer barrel, in another
similar configuration stove:</div>
<div style="font-size:12.8px"><br>
</div>
<div style=""><span style="font-size:12.8px"><a
moz-do-not-send="true"
href="https://www.dropbox.com/sh/af6b6gfihhw4psj/AAD6cuP8q4PMGTCDSMJqfXDGa?dl=0"><a class="moz-txt-link-freetext" href="https://www.dropbox.com/sh/af6b6gfihhw4psj/AAD6cuP8q4PMGTCDSMJqfXDGa?dl=0">https://www.dropbox.com/sh/af6b6gfihhw4psj/AAD6cuP8q4PMGTCDSMJqfXDGa?dl=0</a></a></span><br>
</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">This is a video of this stove with
a taller chimney:</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px"><a moz-do-not-send="true"
href="https://youtu.be/j6BfGrPsvt8" target="_blank">https://youtu.be/j6BfGrPsvt8</a><br>
</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">Greetings</div>
<div style="font-size:12.8px">Roberto Poehlmann</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px"><br>
</div>
<div style="font-size:12.8px">"</div>
<div style="font-size:12.8px"><span style="color:rgb(0,0,0);white-space:pre-wrap">Roberto,</span></div>
<div style="font-size:12.8px">
<pre style="white-space:pre-wrap;color:rgb(0,0,0)">Nice. I would like to see test results for particulates. It should be very clean. It looks like it is loosely based on Crispins flame tube design with holes added in the tube where the Venturi low pressure area is. The holes are at the bottom of the burner, so there is better draft and a good burning area above. If I understand correctly Crispin is using the tube differently, to concentrate the heat and increase the dwell time for the flame in that hot environment. His secondary air is all added before the flame tube. Your design looks more compact and perhaps would be a better choice for a TLUD.
There is a limit to how much gas the burner can handle. When the foil is removed and more primary air is added the burner is overloaded with gas and a tall diffusion flame forms. I have been trying to handle this problem by adding more mixing capability, and have had some improvment, but further work is needed. The problem with the mixing tubes I am using is that along the edges of the combustor, the air exiting the tubes exits at an angle instead of straight out. This holds the gasses below the burner along the edges, and adds to blowing them to the center, overloading the center of the mixer and wasting air at the edges of the combustor. This would not be a problem with your design. You might be able to use two or three of theses mixers side by side to gain a clean higher fire power.
The concentrator ring is intended to mix the wood gas and air, and the Venturi mixer is intended to mix the wood gas and the air, so you have a duplicate mixing system. I am not saying good or bad, just something I notice.
I see Julian has expressed some doubts about the Venturi concept. Good for him. I would be very happy if someone with adiquate equipment and technical ability proved or disproved the TLUD Venturi concept, either way. I perhaps will have to bite the bullet and buy a manometer with the ability to measure down to .001 inch of water column. My rather primative home made manometer did show a slight pressure drop at the mixer, but not enough to get any measurments. Our local college science department didn't seem to be interested.
Attached are some photos of the primary control valve I am currently using very successfully. It looks like something similar might work for you.
Good work Roberto,
Kirk</pre>
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