<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Paul, cc Nathan and list</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Thanks for bringing up the two subjects of a) separately controlling secondary air, and b) oily (mostly seed?) fuels.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I agree that we should be controlling secondary air, but I am pretty sure that we should and can do this with the same controller as for the primary air. Most TLUDs already can and should control primary air, but make no effort to control the secondary air. My reason for preferring to use one controller for both is that the ratio of primary to secondary should always be the same if we want (or can live with) a fixed ratio for excess air. One controller is cheaper and is easier for the cook. Anyone disagree?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>On the subject of using Jaropha seeds, I am pretty sure that we would need a larger amount of “secondary” air than for non-oily fuels, but that there still could be a single air controller (just with a larger SA/PA ratio [ maybe goes from about 6:1 up to 7:1 ??]. Note that these oils cannot combust as they pass through the hot charcoal above the downward moving pyrolysis front (no oxygen in that stream). But I presume the temperature is enough for them to arrive above the char as quite a different set of gases. So, I’d like to hear more about what Nathan found. Any cite we can look up?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I agree with the rest of Paul’s comments. TLUDs are not yet a mature technology - but it is growing up; it is not standing still.</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Apr 29, 2017, at 8:14 AM, Paul Anderson <<a href="mailto:psanders@ilstu.edu" class="">psanders@ilstu.edu</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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To all, 29 April 2017 [This note contains some
new content and explanations for the advancement of TLUD stoves.]<br class="">
<br class="">
1. Ron: I and probably some others have successfully used dung
as the input fuel into TLUDs. I am not recommending dung, but if
it is being burned, then a TLUD is preferred for cleaner burning.<br class="">
<br class="">
2. AD: I agree with Ron that the TLUD stoves are better with both
light and hard (heavy) wood than direct burning of them in any
direct-burning (ICS) stove.<br class="">
<br class="">
3. Main point, to Neil and all: TLUDs are not burning wood
directly. TLUDs turn wood into gases. THEN the gases are
burned. So poplar, maple, maize cobs, dung, etc. are ALL becoming
gases first. THEN the burning of those gases might be somewhat
different (but not as much as the direct burning of those diverse
fuels). <br class="">
<br class="">
TLUD stoves are just arriving into their "young-adult stage." In
contrast: not infancy, not childhood, maybe still "youth", but
certainly not full maturity, and a long way from the "old age" of
the ICS "Inproved or Inadequate" direct-burning cookstoves. This is
because we are still learning about better and better ways of mixing
the combustible gases with the incoming secondary air (SA) (This
is where the BURNING takes place to make the heat that goes to the
pot. TLUDs are DIRECTLY burning GASES, not solid fuels. )
(Please see my "Classification of Stove Technology and Fuels"
documents (1-page and 4-page versions) at
<a class="moz-txt-link-freetext" href="http://www.drtlud.com/2017/04/11/classification-stove-technologies-fuels/">http://www.drtlud.com/2017/04/11/classification-stove-technologies-fuels/</a>
)<br class="">
<br class="">
The <u class="">solid </u>wood and dung etc are an intermediate stage of
the fuel. Sort of a "storage" stage. Then pyrolysis "transforms
solids into gases plus charcoal". The created gases are then burned
SEPARATELY (by centimeters and seconds, but certainly separately)
from where the gases were created. We do not have clear terminology
for this, in layman's terms. The closest might be "gas burning
stoves that make their own gases." <br class="">
<br class="">
So, what development is happening in the early "young-adult" stage?
Control of primary air, learning about solid "intermediate" fuels,
and improving combustion of the gases, as well as "new clothes" with
sizes and mateials. <br class="">
<br class="">
Consider this: We have known of FA (forced air or fan assisted)
TLUD stoves from the 1990s. And there has been much progress. But
NO TLUD on the market has SEPARATE controls for "variable flows" of
primary air (PA) and secondary air (SA). THAT control is what will
make the difference regarding Neil's initial question that pointed
to differences in the initial fuels (and therefore differences in
the resultant gases and quantities of gases that are being burned.)
<br class="">
<br class="">
Note that TLUDs can be made with different flows of PA ans SA by
changing the sizes and number of holes. That is a form of "tuning"
the TLUD for a specific fuel. This works great for one initial
fuel, but only good but acceptable with other fringe fuels. I am
NOT referring to that work as being "variable flows". I am
referring to when the user can change the flows, even during one
batch of fuel.<br class="">
<br class="">
There has been some researach (mostly unreported and set aside) on
variable control of primary and secondary air, using fans. I have
experimented several times. The "million-dollar-grants" have had
laboratory equipment with controlled and measured separate air
flows. Nathan Puffer did it when we were looking at Jatropha SEEDS
as a fuel. Seeds give off additional gases from the vaporization
(not pyrolysis) of combustible vegetable oils (carbohydrates), which
are much more plentiful in seeds than in stems and branches and
leaves, thereby overwhelming the insufficient supply of SA in a
"regular" TLUD-FA. <br class="">
<br class="">
There is a good reason to not have separate control of PA and SA.
That reason is the user, the cook. To need to "dial-in" the right
flow of SA (assuming PA flow stays the same) is, for the most part
and for most non-scientist cooks, an extra task that could easily be
done incorrectly. And there are the financial reasons of increased
cost and maintenance. <br class="">
<br class="">
But with "separate air-flow control" (not an established term and
NOT justifying an acronym like SAC, as in TLUD-SAC), Neil or anyone
could put many very different initial fuels into a TLUD and have
greater control of the burning of the gases. <br class="">
<br class="">
More work is needed before TLUD stoves can reach their full
potential, while growing in "young-adulthood". Today (2017), maybe
40% of what can be known about TLUD stoves is now known (but not
necessarily put into practice by stove manufacturers). <br class="">
<br class="">
(This note is being placed at the EPosts section of my website
<a class="moz-txt-link-abbreviated" href="http://www.drtlud.com/">www.drtlud.com</a> so that it can be accessed continually instead of
only one time on the Stove Listserv.) <br class="">
<br class="">
Paul<br class="">
<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>
<br class="">
</div>
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