<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
Dear Kirk and all,<br>
<br>
Kirk wrote to "All" but it seems to have come only to my address.
So I am sending to the Stoves Listserv Kirk's message (including his
attachment drawing), to which I provide my response after his
message has been read.<br>
PSA<br>
<div class="moz-forward-container">-------- Forwarded Message
--------
<table class="moz-email-headers-table" cellspacing="0"
cellpadding="0" border="0">
<tbody>
<tr>
<th nowrap="nowrap" valign="BASELINE" align="RIGHT">Subject:
</th>
<td>RE: [Stoves] Explaination of downdraft in TLUD updraft
stoves ---was--Re: Mis-information</td>
</tr>
<tr>
<th nowrap="nowrap" valign="BASELINE" align="RIGHT">Date: </th>
<td>Sun, 1 Apr 2018 00:13:11 -0700</td>
</tr>
<tr>
<th nowrap="nowrap" valign="BASELINE" align="RIGHT">From: </th>
<td>Kirk H. <a class="moz-txt-link-rfc2396E" href="mailto:gkharris316@comcast.net"><gkharris316@comcast.net></a></td>
</tr>
<tr>
<th nowrap="nowrap" valign="BASELINE" align="RIGHT">To: </th>
<td>Paul Anderson <a class="moz-txt-link-rfc2396E" href="mailto:psanders@ilstu.edu"><psanders@ilstu.edu></a></td>
</tr>
</tbody>
</table>
<br>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta name="Generator" content="Microsoft Word 15 (filtered
medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:Helvetica;
panose-1:2 11 5 4 2 2 2 2 2 4;}
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Verdana;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:#954F72;
text-decoration:underline;}
pre
{mso-style-priority:99;
mso-style-link:"HTML Preformatted Char";
margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";
color:black;}
span.HTMLPreformattedChar
{mso-style-name:"HTML Preformatted Char";
mso-style-priority:99;
mso-style-link:"HTML Preformatted";
font-family:"Courier New";
color:black;}
span.apple-tab-span
{mso-style-name:apple-tab-span;}
span.apple-converted-space
{mso-style-name:apple-converted-space;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style>
<div class="WordSection1">
<p class="MsoNormal">All,</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have been trying to think how down-draft
might be possible in this stove. I am not convinced that the
Venturi effect alone could do it working against the draft.
The attached drawing might explain how it is possible. What
do you think?</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Kirk H.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sent from <a
href="https://go.microsoft.com/fwlink/?LinkId=550986"
moz-do-not-send="true">Mail</a> for Windows 10</p>
<p class="MsoNormal">________________________________________</p>
<p class="MsoNormal">Reply by Paul is below:<br>
</p>
<p class="MsoNormal"><br>
</p>
<p class="MsoNormal">Kirk and all,<br>
<br>
I have previously posted my thoughts that the co-mingled
primary/secondary air (two purposes of air that are not with
separate entrances) means that the venturi effect is causing a
lowering of air pressure inside the bottom part of the sealed
fuel chamber. <br>
</p>
<p class="MsoNormal"><br>
</p>
<p class="MsoNormal">To test that hypothesis on paper, take your
diagram and place a number of small (2 - 3 mm) holes into the
bottom of the fuel chamber (and therefore with access to
ambient air). It will be functioning as a normal TLUD stove,
not as a downward sucking (DS) stove. To test that
hypothesis in the real world, have a functioning DS stove with
maybe 6 holes in the bottom, closed off with screws. Remove
one screw. observe. Remove a second screw and observe.
Remove more and more screws. That is one test. <br>
</p>
<p class="MsoNormal"><br>
</p>
<p class="MsoNormal">Prediction, the DS function will weaken
with the removal of each screw, until there is an equilibrium
of air pressure inside the bottom of the chamber, and then
(maybe with one more screw being removed) the primary air will
rise through the fuel. Be alert that there might not be any
glowing pyrolysis (normally at the MPF) to allow the creation
of a MPF (pyrolytic front) as in a normally operated TLUD
stove. Be prepared to re-gnite the upper flame (if needed) to
prevent a smoke event.<br>
<br>
The second test is to have a cold start of a "DS stove with
open bottom-holes" that is loaded with fuel, and do a standard
top ignition. And watch to see if the TLUD or DS process
occurs. <br>
<br>
I think that I am correct. The venturi effect on those lower
side hole can still be operational, but it will be pulling out
sideways some of the true primary air that is entering from
the bottom. The result will be no reduction of the air
pressure inside the fuel chamber, and TLUD operation will
dominate.<br>
<br>
Paul</p>
<p class="MsoNormal">__________________________<br>
</p>
<p class="MsoNormal"><o:p> </o:p></p>
<div
style="mso-element:para-border-div;border:none;border-top:solid
#E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal" style="border:none;padding:0in"><b>From:
</b><a href="mailto:psanders@ilstu.edu"
moz-do-not-send="true">Paul Anderson</a><br>
<b>Sent: </b>Saturday, March 24, 2018 6:34 AM<br>
<b>To: </b><a href="mailto:stoves@lists.bioenergylists.org"
moz-do-not-send="true">Discussion of biomass cooking
stoves</a>; <a href="mailto:gkharris316@comcast.net"
moz-do-not-send="true">gkharris316@comcast.net</a><br>
<b>Subject: </b>Re: [Stoves] Explaination of downdraft in
TLUD updraft stoves ---was--Re: Mis-information</p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD</pre>
<pre>Email: <a href="mailto:psanders@ilstu.edu" moz-do-not-send="true">psanders@ilstu.edu</a></pre>
<pre>Skype: paultlud Phone: +1-309-452-7072</pre>
<pre>Website: <a href="http://www.drtlud.com" moz-do-not-send="true">www.drtlud.com</a></pre>
<div>
<p class="MsoNormal">On 3/24/2018 7:39 AM, Ronal W. Larson
wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">Kirk et al<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span">
</span>You have it partially correct - but we are not
talking about a TLUD. There is no MPF (Moving Pyrolysis
Front). Rather, the pyrolysis gases are created by the
downward flowing (very) hot gases.. <o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal">Incorrect. There is no way for the very
hot gases that are the flame at the top to go downward WITH O2
through a substantial layer of hot charcoal and then reach the
raw biomass fuel at temperatures that are going to cause
full-fledged pyrolysis (at least above 400 C) and continue
downward to exit through what are called "primary air inlets"
(but are claimed to be outlets).<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span">
</span>Besides N2, there is a fair amount of CO2 - but no
O2. Much more gas comes out the bottom than enters (all
valuable pyrolysis gases) . Possible only because of the
Venturi effect - not iimportant in TLUDs.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span">
</span>See <a
href="http://www.charcoalproject.org/2010/05/a-man-a-stove-a-mission/"
moz-do-not-send="true">http://www.charcoalproject.org/2010/05/a-man-a-stove-a-mission/</a>
.<o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal">My very quick look at this did not find
speciic content about proving the downdraft issue. (If
anyone finds specific content, please call it to my/our
attention.)<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">and:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><a
href="https://foodtank.com/news/2017/05/nathaniel-mulcahy-worldstove-talks-clean-cooking-stoves/"
moz-do-not-send="true">https://foodtank.com/news/2017/05/nathaniel-mulcahy-worldstove-talks-clean-cooking-stoves/</a><o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal">Also an Info item, not a science item. <br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">and <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span">
</span><a
href="https://www.youtube.com/watch?v=QsH_Gh-n2Mg"
moz-do-not-send="true">https://www.youtube.com/watch?v=QsH_Gh-n2Mg</a><o:p></o:p></p>
</div>
</blockquote>
<p class="MsoNormal">This is the FORCED AIR Lucia stove and is
not relevent to the current conversation.<br>
<br>
See further down my reply to Noil (or was the Neil), and
Crispin and Kirk.<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-tab-span">
</span>I will look for more technical descriptions. Note
these above emphasize the biochar part of cooking.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Ron<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">On Mar 24, 2018, at 1:52 AM, Kirk
H. <<a href="mailto:gkharris316@comcast.net"
moz-do-not-send="true">gkharris316@comcast.net</a>>
wrote:<o:p></o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">All,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">I like Noll’s remarks. If
down-draft was occurring the gasses would cool as
they pass through the unburned fuel and so the
vapors would condense and become smoke. There would
be lots of smoke exiting the primary holes. This is
not happening in the video. Creosote would soon
coat the entire bottom and annulus portions of the
stove and clog the primary air openings. Creosote
may also coat the unburned fuel and so restrict the
air flow. Also the unburned fuel would get hotter
and hotter and possibly begin pyrolysing in mass.<o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
</blockquote>
<p class="MsoNormal">VERY good point. Something that can be
studied via observation without lots of expensive equipment.<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Paul’s question about how air
would get to the MPF from above is unanswered. The
air would have to pass through the flame. This may
be possible because the flame is a gas and gasses
are permeable. But as the air passes through the
flame, the oxygen would get used up so only nitrogen
would descend into the fuel and the MPF would go
out.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Crispin remarks that it would
have to be an air restricted situation for
down-draft to occur and only around the edges. This
sounds true, and you would not get much fire power
in an air restricted situation. And remember how
TLUDs go out when turned down too much? Would
whatever this is have the same problem?<o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
</blockquote>
<p class="MsoNormal">Yes, such a flow is to be considered. I
visualize it as a donut. Primary air upward through the donut
hole and then some pyrolytic gases downward as an annulus (the
sides of the donut. Also to be studied.<br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">With adequate primary air to keep
the MPF going, adequate secondary air, and an open
top the gasses inside would be actively interacting
with the outside atmosphere. All the gases,
including near the edge of the chamber are hotter
than the atmosphere and subject to rising via
buoyancy, although perhaps at different rates. <span
class="apple-converted-space"> </span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">It is unlikely that it is
down-draft. <span class="apple-converted-space"> </span><o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
</blockquote>
<p class="MsoNormal">CLARIFICATION: Downdraft has at least two
meanings. One can be the movement of gases, such as some
pyrolytic gases moving downward in the fuel column (what we
are discussing). The other is as in a downdraft gasifier
there the hot gases exit the gasifier by going downward
THROUGH the bottom layer of red-hot (white hot) charcoal.<br>
<br>
So the wording could be It is unlikely that it is
down-draft [gasification] Which it is not in this case.
OR <span class="apple-converted-space">It is unlikely
that [there] is down-draft [of some gases within the column
of fue.]. (which is what is being discussed.) </span><br>
<br>
<span class="apple-converted-space">NOTE: This is te the most
vigorous TECHNICAL-BASED DISCUSSION on the Stoves Listserv
for quite some time. I like it!!</span><br>
<br>
<span class="apple-converted-space">Paul</span><br>
<br>
<o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Kirk H.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Sent from<span
class="apple-converted-space"> </span><a
href="https://go.microsoft.com/fwlink/?LinkId=550986"
moz-do-not-send="true"><span style="color:#954F72">Mail</span></a><span
class="apple-converted-space"> </span>for Windows
10<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0in 0in 0in">
<div>
<p class="MsoNormal"><b>From:<span
class="apple-converted-space"> </span></b><a
href="mailto:psanders@ilstu.edu"
moz-do-not-send="true"><span
style="color:#954F72">Paul Anderson</span></a><br>
<b>Sent:<span class="apple-converted-space"> </span></b>Friday,
March 23, 2018 6:09 PM<br>
<b>To:<span class="apple-converted-space"> </span></b><a
href="mailto:wastemin1@verizon.net"
moz-do-not-send="true"><span
style="color:#954F72">Hugh McLaughlin</span></a>;<span
class="apple-converted-space"> </span><a
href="mailto:Stoves@lists.bioenergylists.org"
moz-do-not-send="true"><span
style="color:#954F72">Stoves and biofuels
network</span></a><br>
<b>Subject:<span class="apple-converted-space"> </span></b>Re:
[Stoves] Explaination of downdraft in TLUD updraft
stoves ---was --Re: Mis-information<o:p></o:p></p>
</div>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Hugh,<br>
<br>
Thanks for the reply. I am forwarding it to the
Stoves Listserv. <span
class="apple-converted-space"> </span><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>
<br>
<br>
<o:p></o:p></p>
</div>
<pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD</pre>
<pre>Email: <a href="mailto:psanders@ilstu.edu" moz-do-not-send="true"><span style="color:#954F72">psanders@ilstu.edu</span></a></pre>
<pre>Skype: paultlud Phone: +1-309-452-7072</pre>
<pre>Website: <a href="http://www.drtlud.com/" moz-do-not-send="true"><span style="color:#954F72">www.drtlud.com</span></a></pre>
<div>
<div>
<p class="MsoNormal">On 3/22/2018 5:41 PM, Hugh
McLaughlin wrote:<o:p></o:p></p>
</div>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div id="yui_3_16_0_ym19_1_1521756600094_10264">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif">Paul,</span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10270">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10389">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif">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.</span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10542">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10543">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif">Hugh</span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10513">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10514">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif">Noll's
comment is copied below:</span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10390">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
<div id="yui_3_16_0_ym19_1_1521756600094_10503">
<div>
<p class="MsoNormal" style="background:white"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif">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.<span class="apple-converted-space"> </span></span><o:p></o:p></p>
</div>
</div>
<div>
<p class="MsoNormal"
style="margin-bottom:12.0pt;background:white;background-position:initial
initial;background-repeat:initial initial"><span
style="font-size:10.0pt;font-family:"Verdana",sans-serif"> </span></p>
</div>
<div>
<div>
<div>
<div>
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:10.0pt;font-family:"Arial",sans-serif">On
Thursday, March 22, 2018 9:05 AM, Paul
Anderson<span
class="apple-converted-space"> </span><a
href="mailto:psanders@ilstu.edu"
moz-do-not-send="true"><span
style="color:#954F72"><psanders@ilstu.edu></span></a><span
class="apple-converted-space"> </span>wrote:</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"
style="margin-bottom:12.0pt;background:white;background-position:initial
initial;background-repeat:initial initial"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif"> </span></p>
<div>
<div id="yiv9198720191">
<div>
<p class="MsoNormal"
style="text-align:center;background:white"
align="center"><b><span
style="font-size:14.0pt;font-family:"Helvetica",sans-serif">Explanation
of downdraft in the fuel chamber
of TLUD (UP draft) stoves.</span></b><o:p></o:p></p>
<p class="MsoNormal"
style="text-align:center;background:white"
align="center"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif">Paul
S. Anderson, PhD 21 March 2018</span><o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif">Stovers,
Previously I wrote:<br>
*******************<br>
This link takes you to [what I
am calling Video A.)<br>
<a
href="https://www.youtube.com/watch?annotation_id=annotation_1962734105&feature=iv&src_vid=wzN-cYR84_Y&v=b0vM9aD78XY"
target="_blank"
moz-do-not-send="true"><span
style="color:#954F72">https://www.youtube.com/watch?annotation_id=annotation_1962734105&feature=iv&src_vid=wzN-cYR84_Y&v=b0vM9aD78XY</span></a><br>
Same fellow. and showing
clearly UPdraft. Side by side
comparisons. Well worth
watching. <span
class="apple-converted-space"> </span><br>
That is dated 2015. I hope that
somebody will delve into this
further.</span><o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif">*****************************</span><o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif"> 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>
<span
class="apple-converted-space"> </span><a
href="https://www.youtube.com/watch?v=wzN-cYR84_Y" target="_blank"
moz-do-not-send="true"><span
style="color:#954F72">https://www.youtube.com/watch?v=wzN-cYR84_Y</span></a> <span
class="apple-converted-space"> </span></span><o:p></o:p></p>
</div>
</div>
<div style="margin-bottom:12.0pt">
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif">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. <span
class="apple-converted-space"> </span><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. <span
class="apple-converted-space"> </span><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<span
class="apple-converted-space"> </span><b><u>BOTH<span
class="apple-converted-space"> </span></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. <span
class="apple-converted-space"> </span><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. <span
class="apple-converted-space"> </span><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. <span
class="apple-converted-space"> </span><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. <span
class="apple-converted-space"> </span><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. <span
class="apple-converted-space"> </span><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
class="apple-converted-space"> </span></span><o:p></o:p></p>
</div>
</div>
<div style="margin-bottom:12.0pt">
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif">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. <span
class="apple-converted-space"> </span><br>
--<span
class="apple-converted-space"> </span><br>
Doc / Dr TLUD / Prof. Paul
S. Anderson, PhD<br>
Email: <span
class="apple-converted-space"> </span><a
href="mailto:psanders@ilstu.edu" target="_blank" moz-do-not-send="true"><span
style="color:#954F72">psanders@ilstu.edu</span></a><u><span
style="color:blue"> <span
class="apple-converted-space"> </span></span></u>Skype:
paultlud Phone:<span
class="apple-converted-space"> </span><span
class="MsoHyperlink">+1-309-452-7072</span><u><span
style="color:blue"> <span
class="apple-converted-space"> </span></span></u>Website: <span
class="apple-converted-space"> </span><a
href="http://www.drtlud.com/"
target="_blank"
moz-do-not-send="true"><span
style="color:#954F72">www.drtlud.com</span></a></span><o:p></o:p></p>
</div>
</div>
<div>
<div>
<div>
<div style="margin-bottom:12.0pt">
<div>
<p class="MsoNormal"
style="background:white"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<p class="MsoNormal"
style="margin-bottom:12.0pt;background:white;background-position:initial
initial;background-repeat:initial initial"><span
style="font-size:12.0pt;font-family:"Helvetica",sans-serif"> </span><o:p></o:p></p>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
<p class="MsoNormal"><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif">_______________________________________________<br>
Stoves mailing list<br>
<br>
to Send a Message to the list, use the email address<br>
</span><a
href="mailto:stoves@lists.bioenergylists.org"
moz-do-not-send="true"><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif;color:#954F72">stoves@lists.bioenergylists.org</span></a><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif"><br>
<br>
to UNSUBSCRIBE or Change your List Settings use the
web page<br>
</span><a
href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org"
moz-do-not-send="true"><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif;color:#954F72">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org</span></a><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif"><br>
<br>
for more Biomass Cooking Stoves, News and
Information see our web site:<br>
</span><a href="http://stoves.bioenergylists.org/"
moz-do-not-send="true"><span
style="font-size:13.5pt;font-family:"Helvetica",sans-serif;color:#954F72">http://stoves.bioenergylists.org/</span></a><o:p></o:p></p>
</div>
</blockquote>
</div>
<p class="MsoNormal"><br>
<br>
<br>
<br>
<o:p></o:p></p>
<pre>_______________________________________________</pre>
<pre>Stoves mailing list</pre>
<pre><o:p> </o:p></pre>
<pre>to Send a Message to the list, use the email address</pre>
<pre><a href="mailto:stoves@lists.bioenergylists.org" moz-do-not-send="true">stoves@lists.bioenergylists.org</a></pre>
<pre><o:p> </o:p></pre>
<pre>to UNSUBSCRIBE or Change your List Settings use the web page</pre>
<pre><a href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org" moz-do-not-send="true">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org</a></pre>
<pre><o:p> </o:p></pre>
<pre>for more Biomass Cooking Stoves, News and Information see our web site:</pre>
<pre><a href="http://stoves.bioenergylists.org/" moz-do-not-send="true">http://stoves.bioenergylists.org/</a></pre>
<pre><o:p> </o:p></pre>
</blockquote>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:black"><o:p> </o:p></span></p>
</div>
</div>
</body>
</html>