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<DIV><FONT size=2 face=Arial>All,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>These are good discussions on burning CO and
swirl. I know that Aprovecho has developed a good charcoal stove based on
experimentation by labratory manager Sam Bentson. My own experience is
much less but I do see in my TLUD combustor blue CO flames in the Venturi gas
mixer after the hydrocarbon flames have gone out. I do not know how
thurough this burning of CO is. My speculation is that thoroughly mixing
adiquate air with the CO, and keeping a flame going above the coals, as per
Sam's findings,</FONT><FONT size=2 face=Arial> does a good job of
burning CO for those who want to burn the char.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Swirl is a method I use for getting more dwell
time for the flame in the combustor section of the stove. Swirl is not
used for mixing because the gasses are thuroughly mixed by the Venturi gas mixer
before they pass through the stationary fan. Also swirl is not a
good mixing method because it will seperate cooler denser gasses from hotter
less dense gasses like a centrifuge. I do not use turbulance for mixing
because I believe the Venturi method is more thorough, though I agree with Dr.
Larson that adding turbulance will improve combustion in a non-Venturi
burner. As with any mixing method, the Venturi method can be overwhelmed
if to much wood gas is run through it, in agreement with Dean Still's
statements. So far my 6' diameter combustor can operate efficiently up to
about 3 kw. Above this both the mixer and stationary fan are not
adiquate. Adding more mixing capacity by adding more Venturi
mixers helps with mixing, as three stove camp participants who helped me,
Roberto, Steve and Cody showed me last week at Aprovecho's stove
camp. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The stationary fan has 6 blades and the shape
of each blade is a smooth curve. By the Coanda effect a flame up
to 3kw can cling to the back side of the blade and leave the blade's trailing
edge at a good flat angle. A higher power flame produces so much
buoyancy that the flame is seperated from the blade early and goes off at a
fairly steep, not so good angle. A new stationary fan design suggested by
Dr. Larson may solve this problem and with additional Venturi mixers
give the combustor the capability to handle higher power levels.
We shall see.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Best to all,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Kirk</FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"
dir=ltr>
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=deankstill@gmail.com href="mailto:deankstill@gmail.com">Dean
Still</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">Discussion of biomass cooking
stoves</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, August 04, 2015 9:58
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Stoves] Request to get
partners in a possible TLUD stove improvement project</DIV>
<DIV><BR></DIV>
<DIV dir=ltr>Ron,
<DIV><BR></DIV>
<DIV>IMO, swirl is not as powerful a cleaner stove technique compared to 1,)
limiting the rate of woodgas being made or 2.) the generated mixing ability.
We start by limiting the rate of reactions by decreasing primary air. Then add
higher velocity jets of secondary air.</DIV>
<DIV><BR></DIV>
<DIV>Swirl is great but I think that it is gravy. May be wrong!</DIV>
<DIV><BR></DIV>
<DIV>Best,</DIV>
<DIV><BR></DIV>
<DIV>Dean</DIV></DIV>
<DIV class=gmail_extra><BR>
<DIV class=gmail_quote>On Tue, Aug 4, 2015 at 6:13 PM, Ronal W. Larson <SPAN
dir=ltr><<A href="mailto:rongretlarson@comcast.net"
target=_blank>rongretlarson@comcast.net</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>
<DIV style="WORD-WRAP: break-word">Dean:
<DIV><BR></DIV>
<DIV><SPAN style="WHITE-SPACE: pre-wrap"></SPAN>I want to emphasize - no
making of a new stove intended. This is to be only an addition to
stoves that (hopefully, but not necessarily) have already been tested.
Looking for a breadth of existing designs. Hopefully these are already
in the best “balance” they could achieve. This is to see whether that
can be improved.</DIV>
<DIV><BR></DIV>
<DIV><SPAN style="WHITE-SPACE: pre-wrap"></SPAN>What have you seen in swirl
approaches?</DIV>
<DIV><BR></DIV>
<DIV><SPAN style="WHITE-SPACE: pre-wrap"></SPAN>What have you seen in
turbulence enhancers?</DIV>
<DIV><BR></DIV>
<DIV><SPAN style="WHITE-SPACE: pre-wrap"></SPAN>Thanks for the quick
feedback.</DIV>
<DIV><BR></DIV>
<DIV>Ron</DIV>
<DIV><BR></DIV>
<DIV><BR>
<DIV>
<DIV>On Aug 4, 2015, at 6:52 PM, Dean Still <<A
href="mailto:deankstill@gmail.com"
target=_blank>deankstill@gmail.com</A>> wrote:</DIV><BR>
<BLOCKQUOTE type="cite">
<DIV dir=ltr>Hi Ron,
<DIV><BR></DIV>
<DIV>In my opinion, reducing emissions in a TLUD or any stove requires
testing with emissions equipment. The great stove combines many factors
working together. "Swirl" is only one part. Kirk gets good results when
everything is in balance. "Swirl" is not powerful enough to overcome
problems in the balance.</DIV>
<DIV><BR></DIV>
<DIV>I completely agree that anyone with tin snips and emission equipment
and perseverance can make low emission stoves. If you are lucky it
takes a shorter time. So what? Even if you are unlucky it happens
eventually. Drink more coffee.</DIV>
<DIV><BR></DIV>
<DIV>Best,</DIV>
<DIV><BR></DIV>
<DIV>Dean</DIV></DIV>
<DIV class=gmail_extra><BR>
<DIV class=gmail_quote>On Tue, Aug 4, 2015 at 5:40 PM, Ronal W. Larson
<SPAN dir=ltr><<A href="mailto:rongretlarson@comcast.net"
target=_blank>rongretlarson@comcast.net</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>Stove list cc Kirk<BR><BR>
From what I can understand, the lowest emission (particulates, CO
is easy) values from TLUDs have been from stoves designed and tested
(last week) by Kirk Harris. One reason seems to be that he has
achieved a swirl, using (as described on this list often) a fan blade
shape.<BR><BR> I recall a few other uses of
the term “swirl”, but know of no significant tests like those by
Kirk.<BR><BR> In recent conversations, Kirk
has agreed to be part of an off-list TLUD stove group to investigate a
different means of achieving swirl. It seems to be cheap and applicable
to most TLUD stoves.<BR><BR> The main
advantage of a swirl is more flame time spent in the stove; to get
low emissions, hot gases, not flames, need to be hitting the cook
pot.<BR><BR> The proposed approach also
should increase turbulence. I do not recall any TLUD that tried to
achieve turbulence (to get the mixing needed for shorter path
lengths and more complete combustion). Anybody know of designs to
achieve turbulence other than added disk or washer shapes?<BR><BR>
The reason for not saying much now is to save list
members’ time and energy. This is not a guaranteed
approach.<BR><BR> Anyone joining should
want to see this open-source (no patents).<BR><BR>
Anticipated time commitment for a first design - a few hours with
tin snips. Metal cost a buck or two. Probably can work with
clay as well.<BR><BR> If anyone knows of past
swirl or turbulence experiments (or modeling) in TLUDs, your input now
could save Kirk and I (and anyone else wanting to join) a lot of time -
especially if those results were negative.<BR><BR>Ron<BR><BR>
feel free to call <A href="tel:303-526-9629"
target=_blank value="+13035269629">303-526-9629</A>, if that would
help.<BR>_______________________________________________<BR>Stoves
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clear=all>
<DIV><BR></DIV>-- <BR>
<DIV>
<DIV dir=ltr>
<DIV>Dean Still</DIV>
<DIV dir=ltr>Executive Director
<DIV>Aprovecho Research Center</DIV>
<DIV>PO Box 1175</DIV>
<DIV>76132 Blue Mountain School Road</DIV>
<DIV>Cottage Grove, OR 97424</DIV>
<DIV><A href="tel:%28541%29%20767-0287" target=_blank
value="+15417670287">(541)
767-0287</A></DIV></DIV></DIV></DIV></DIV>_______________________________________________<BR>Stoves
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clear=all>
<DIV><BR></DIV>-- <BR>
<DIV class=gmail_signature>
<DIV dir=ltr>
<DIV>
<DIV>Dean Still</DIV>
<DIV dir=ltr>Executive Director
<DIV>Aprovecho Research Center</DIV>
<DIV>PO Box 1175</DIV>
<DIV>76132 Blue Mountain School Road</DIV>
<DIV>Cottage Grove, OR 97424</DIV>
<DIV>(541) 767-0287</DIV></DIV></DIV></DIV></DIV></DIV>
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