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Hugh,<br>
<br>
Thanks for the reply. I am forwarding it to the Stoves Listserv.
<br>
<br>
The impact of the air being drawn in (creating a draft onto the
ignited stick) should be able to be checked by shielding the flame
from the direct draft.<br>
<br>
To all: How can we get copies of these messages to Heath Putnam
for his input?<br>
<br>
Paul<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 3/22/2018 5:41 PM, Hugh McLaughlin
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:333746150.5410391.1521758463596@mail.yahoo.com">
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<div id="yui_3_16_0_ym19_1_1521756600094_10264">Paul,</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10270"><br>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10389">I am
unconvinced. One of the comments (the first - Arthur Noll)
provides an explanation - it is the air being drawn into the
base (primary air inlets) that stimulate the burning at the
bottom.</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10542"><br>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10543">Hugh<br>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10513"><br>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10514">Noll's comment
is copied below:<br>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10390"><br>
</div>
<div dir="ltr" id="yui_3_16_0_ym19_1_1521756600094_10503">That
is interesting, but I'm not convinced that pyrolysis products
are coming out of the bottom. You don't see any smoke coming
out the bottom until you put the flaming stick in there. The
stick could be producing the smoke that hits the bottom of the
can, turns sideways and joins the flow of air, much of which
is rising up the sides between the containers, while smaller
amounts are going in to the wood. If it were correct that
products of pyrolysis were going down and then up, I would
expect to see a significant amount of smoke coming out the
bottom and up the sides all the time, not just when the stick
was put in. And I would expect to see soot and tar
precipitating out on the surfaces between the containers.
Pyrolysis produces a combination of gases, smoke, soot and
tar. It is messy. I have built these stoves and this area is
always clean, even after many burns, just like what you have
is clean. I have always felt that the smoke, tar and gas from
the pyrolosis was rising up, and the preheated air coming out
the secondary air holes, going into this mixture of flammable
gas and vapor, made the jets of flame. I don't think it makes
any difference whether you have a jet of air going into a mass
of flammable gas or if you have a jet of flammable gas going
into a mass of air, both can give you a jet of flame.
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10580"><span></span></div>
<div class="qtdSeparateBR"><br>
<br>
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<div dir="ltr"><font size="2" face="Arial"> On Thursday,
March 22, 2018 9:05 AM, Paul Anderson
<a class="moz-txt-link-rfc2396E" href="mailto:psanders@ilstu.edu"><psanders@ilstu.edu></a> wrote:<br>
</font></div>
<br>
<br>
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<div id="yiv9198720191">
<div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal;"
align="center"><b style=""><span
style="font-size:14.0pt;color:black;">Explanation
of downdraft in the fuel chamber of TLUD (UP
draft) stoves.</span></b></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:0in;margin-bottom:.0001pt;text-align:center;line-height:normal;"
align="center"><span
style="font-size:12.0pt;color:black;">Paul S.
Anderson, PhD<span style=""> </span>21
March 2018</span></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:0in;margin-bottom:.0001pt;line-height:normal;"><b
style=""><span
style="font-size:14.0pt;color:black;"></span></b><span
style="color:black;">Stovers,<span style="">
</span>Previously I wrote:<br>
*******************<br>
This link takes you to [what I am calling Video
A.)<br>
</span><a rel="nofollow" target="_blank"
href="https://www.youtube.com/watch?annotation_id=annotation_1962734105&feature=iv&src_vid=wzN-cYR84_Y&v=b0vM9aD78XY"
moz-do-not-send="true"><span style="color:blue;">https://www.youtube.com/watch?annotation_id=annotation_1962734105&feature=iv&src_vid=wzN-cYR84_Y&v=b0vM9aD78XY</span></a><span
style="color:black;"><br>
Same fellow. and showing clearly UPdraft.
Side by side comparisons. Well worth watching.
<br>
That is dated 2015. I hope that somebody will
delve into this further.</span></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:0in;margin-bottom:.0001pt;line-height:normal;"><span
style="color:black;">*****************************</span></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:0in;margin-bottom:.0001pt;line-height:normal;"><span
style="color:black;"> First, we all should thank
Heath Putnam for his research and for reporting
it publicly. He also provided an earlier video
that lh cheng saw and called to our attention:<br
style="">
</span><a rel="nofollow" target="_blank"
href="https://www.youtube.com/watch?v=wzN-cYR84_Y"
moz-do-not-send="true"><span style="color:blue;">https://www.youtube.com/watch?v=wzN-cYR84_Y</span></a><span
style="color:black;"> </span></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:12.0pt;line-height:normal;"><span
style="color:black;">This I am calling Video B.
Although dated earlier, it is better to watch
Video A first.<br>
<br>
After sleeping on this question last night, I
think I have an explanation. And it also would
explain what Nate Mulcahey presented as the
"Everything Nice Stove" which he claimed was not
a TLUD stove and claimed to be a downdraft flow
of the pyrolytic gases (or Opposite draft).
Putnam's work shows (but does not explain) the
answers about downdraft in updraft TLUD stoves.
<br>
<br>
The big clue (revealed in video (A) above) is
the difference between the two trial units. The
difference is a sealed bottom that enables a
"co-mingled air supply zone" for somewhat
restricted primary and secondary air versus
abundant secondary air that arrives separately
from the supply of primary air. <br>
<br>
If the primary air entry is direct or very
nearly direct and sufficient even with a small,
restricted flow, it will sustain the migratory
pyrolytic front (MPF), and all the air and gases
will flow upward. This is the CLASSIC
description of TLUD operation.<br>
<br>
But consider the case of a TLUD-design stove
that has a closed bottom (or is sitting
reasonably tightly on a flat surface that
prevents entry of abundant air) AND also has
somewhat limited entry (via 4 holes in Putnam's
glass outer cylinder) of air for <b><u>BOTH </u></b>primary
and secondary air into a space (a "co-mingled
air supply zone") from which BOTH types of air
must be drawn. Therefore, the only exit is
upward. The only DRAFT for the stove is powered
by the flame of the burning gases at the top.
<br>
<br>
Consider the case of a functioning TLUD stove
when the MPF is below a layer of charcoal about
3 to 6 cm down from the top, with another 7 to
12 cm of raw fuel below the MPF. The pyrolysis
occurs, and the hot gases tend to rise upward
through the layer of char and into the zone of
the cooking flame. But the flame requires
secondary air, which can only come up in the
ring (annulus) between the two cylinders, and it
does come up. This is the vast majority of the
total supply of air (about 5 units for secondary
to 1 unit of primary air). In fact, that
natural draft by the flame is pulling the air
from the "co-mingled air supply zone" (that one
place of air supply which is also feeding the
primary air). There is therefore a reduction
of air pressure below the MPF, and that means
less movement of the primary air upwards. <br>
<br>
The result is that there is sufficient lower
pressure that SOME of the pyrolytic gases move
downward. Probably some swirling also, or some
channels of gases going down but with SOME (at
least some) primary air (the O2 is the important
part) moving to the MPF. <br>
With a little bit of time, some of the pyrolytic
gases reach the entry holes of the primary air
and leak outward into the "co-mingled air supply
zone" where there is fresh air entering and
where those gases can be combusted (as shown in
the Putnam demonstration in Video B).
Impressive. And if there is no flame down
there, those pyrolytic gases can be pulled
upward to become part of the upward flowing
secondary air THAT IS NOW PRE-MIXED (-but rather
diluted to some unknown amount -) WITH
COMBUSTIBLE GASES. Nice trick, and you can see
Putnam's demonstration of a taller, stronger
flame (Video A). This is important.
Pre-mixing is to be encouraged. But it should
be understood and done intentionally to attain
consistent results. <br>
<br>
BUT in the described simple setup, production of
the pyrolytic gases is suffering. There is a
somewhat deficiency of primary air. That could
be forgiven (or overlooked or ignored) except
for one very important factor:<br>
<br>
When the downdraft is occurring, the stove user
loses some control over the fire. The draft
from the burning gases is now regulating (in
part) the operations of the TLUD stove. The
normal control of a TLUD fire is by closing off
some primary air, or using a small fan, but
these are no longer as effective because of the
co-mingled air. As the flame at the top
changes when there is downward flow (shown by
Putnam), there is a ripple effect to the air
flows. Adjust, then adjust again, and then
adjust again. <br>
<br>
You can look at the Champion TLUD (only one hole
for primary air entry) or the Quad or the Troika
(by Awamu) with only one entry for primary air,
or some of the other more established true TLUD
stoves. The Peko Pe by Wendelbo also keeps the
two air sources separate. Then look at
Putnam's variation and at the Everything Nice
stove and see how the primary and secondary air
are comingled and subjected to the draft created
at the top of the stove.<br>
<br>
Also consider what would happen if there
actually was sufficient downward draft for the
FULL reversal of the air flow in the fuel
chamber. At the top there is flame. And how
is there any O2 surviving in that flame so that
it could go downward enough to go through the 3
to 6 (and deeper) layer of hot charcoal in order
for O2 to reach FROM ABOVE the top side of the
MPF and to sustain that MPF for sending gases
further downward? And then those pyrolytic
gases would need to go out through what were the
primary air inlet holes, and then be mixed with
secondary air (but never catching fire because
somehow there was not a spark there, even at the
end of the batch with red-glowing coals????),
and then rising in the annulus between the two
cylinders, and only when entering the area of
the main flame would those gases combust. But
this supposition of FULL reversal of the air
flow is impossible because there are no
pyrolytic gases moving upward from the MPF. </span></div>
<div class="yiv9198720191MsoNormal"
style="margin-bottom:12.0pt;line-height:normal;"><span
style="color:black;">Conclusion: In a TLUD
stove, there can be PARTIAL downward drafting of
the created pyrolytic gases when caused by
natural draft of secondary air to counteract the
flow of primary air. This is educational, but
what is possible is not necessarily desirable or
practical. <br>
-- <br>
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD<br>
Email: </span><a rel="nofollow"
ymailto="mailto:psanders@ilstu.edu"
target="_blank" href="mailto:psanders@ilstu.edu"
moz-do-not-send="true"><span style="color:blue;">psanders@ilstu.edu</span></a><u><span
style="color:blue;"><span style=""> </span></span></u><span
style="color:black;">Skype: paultlud Phone:
</span><a rel="nofollow" href=""
moz-do-not-send="true"><span style="color:blue;">+1-309-452-7072</span></a><u><span
style="color:blue;"><span style=""> </span></span></u><span
style="color:black;">Website: </span><a
rel="nofollow" target="_blank"
href="http://www.drtlud.com/"
moz-do-not-send="true"><span style="color:blue;">www.drtlud.com</span></a></div>
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