<div dir="ltr">Kirk,<div class="gmail_extra"><br><div class="gmail_quote">I'll try and respond to your comments but it may take more than one try.</div><div class="gmail_quote">I lack the numbers and formula to backup my comments, but its fun to waive my arms around with pretense.<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff">
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">On the question of obstruction, I have to disagree
with you. </font><font size="2" face="Arial">The Venturi mixer I am working on
reduces the open area to .5 that of the fuel reactor
chamber. Your design reduces the open area from 12 inch dia
to 2 inch dia which is 113 sq in to 3.14 sq in. That is .028 the open
area of the fuel reactor chamber, which is much more restriction than I am
using.</font></div></div></blockquote><div>Fair enough. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> You must be getting an incredible velocity through the 2 in pipe,
which would be giving you a substantial drop in pressure via the Venturi
effect. </font></div></div></blockquote><div>I think this Venturi effect would occur at the restriction at the base of the 2 inch pipe not at the top where it is straight.</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> It would be very interesting to get pressure measurements
throughout your stove (with the secondary air entrance open/closed, and
compared to a straight wall stove of the same height for a control). Your
placement of the secondary air entrance is perfect to use the Venturi pressure
reduction for mixing.</font></div></div></blockquote><div>I don't think so, same as above reason. The low pressure is caused by the chimney above, there is no solid restriction to cause a venturi effect. The incoming secondary air could be construed as a restriction. ???</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> I have not found tangential secondary air mixing to
work very well, but I am guessing that the increased pressure difference makes
it work for you. </font></div></div></blockquote><div>In this case its a marginal difference at best. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> </font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">I very much like the way you have found to
<strong><u>pre-mix</u></strong> the wood gas with the secondary air. I had
thought it would be much more difficult to achieve this. You have cleverly
increased the wood gas velocity so it is faster than the flame
can burn back, and thus give the gasses time to pre-mix before they
burn.</font></div></div></blockquote><div>"Cleverly" implies precognition. There was none. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> When the mixture ignites in the mixing area, the high
gas velocity just pushes the flame out. Or perhaps there is
always a small amount of flame in the mixing zone,</font></div></div></blockquote><div>After initial ignition there is no flame in the mixing zone. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> but the gasses are moving so
fast that the majority of gas doesn't burn until it reaches the burning
area. Or perhaps the gasses mix and begin combusting, but because of the
gas velocity they don't have time to burn completely in the mixer area.
Even well mixed gasses take time to burn. </font></div></div></blockquote><div>Not much time. I have previously described a paper thin flat horizontal disc of blue flame. It could also be described as a soap film. This is where a flame front of premixed gasses has a matching flame speed to the gas flow. It is a hard flamr to stabilize, but it appears to be only a molecule thick and could be described as very fast. No unlike a candle flame on a space shuttle in appearance but not in it function.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> The only way I can see that
there would be no flame in the mixing area is if the mixture is below ignition
temperature.</font></div></div></blockquote><div>Yes. It needs a spark.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff">
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">It appears to be a rapid mixing technique,
though you have designed for narrow and tall whereas I designed for wide and
short. Both will find their place. The height of the
cone that accelerates the wood gas plus the height of the mixer
plus the height of the cone to decelerate the mixture and hold the flame adds up
to some height. That is not a negative if it works for the
application. </font></div></div></blockquote><div>Your work has more relevance to this list. Mine, so far is mostly a teaching tool for a class of one.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> </font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">How do you use the flame for cooking? A grill
over the top? A sunken pot?</font></div></div></blockquote><div>I don't. It would have to be in a box with a chimney off to the side. Likely to complex and fussy and ambitious for the real world. </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff">
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">What is the fire power? </font></div></div></blockquote><div>I need to put this on a scale sometime. I used to have an intelligent guess but I forgot what it is.</div><div>8 inches deep by 12 inches diameter, wood pellets, 40 lbs/ ft3 @ 8000 btus/lb, apply assumption , 20% weight char residue @ 13000btus/lb, duration -3 hours.... Anyone:)</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> The constriction must
be creating a back pressure that is slowing pyrolysis, and thus fire
power. This might be countered by the large diameter fuel reactor chamber
providing a large pyrolysis front and lots of wood gas. </font></div></div></blockquote><div>Controlled mostly by under air primary supply with a top end maximum limited by the two inch pipe.</div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div><font size="2" face="Arial"> It is natural
draft and with how much turn-down?</font></div></div></blockquote><div>I need a scale to know. </div><div><br></div><div>Off to work,</div><div>More later.</div><div>Still under 60:)</div><div>Alex </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div bgcolor="#ffffff"><div> </div>
<div><font size="2" face="Arial">I agree with you on the concern for material
life. Your design allows the materials some cooling by giving off
heat to the outside. My design holds the material in the heat. The
only cooling I get is from the secondary air entering and picking up some of the
heat. Things often glow red hot. Material life will be a serious
concern for my design, but this is the twenty-first century, and materials
science has progressed. Possible solutions include making the mixers
from ceramics or other heat resisting material, and designing for cheap and easy
replacement of the heat stressed parts.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">Very nice concept! Thank you for
sharing.</font></div>
<div><font size="2" face="Arial"></font> </div>
<div><font size="2" face="Arial">Kirk H.</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"><b>From:</b>
<a title="aenglish444@gmail.com" href="mailto:aenglish444@gmail.com" target="_blank">alex
english</a> </div>
<div style="FONT:10pt arial"><b>To:</b> <a title="stoves@lists.bioenergylists.org" href="mailto:stoves@lists.bioenergylists.org" target="_blank">Discussion of biomass cooking
stoves</a> </div>
<div style="FONT:10pt arial"><b>Sent:</b> Thursday, September 29, 2016 4:22
AM</div>
<div style="FONT:10pt arial"><b>Subject:</b> Re: [Stoves] Rapid mixing</div>
<div><br></div>
<div dir="ltr">Kirk,
<div>Its quite wonderful what you have demonstrated. A holy grail of sorts.
The durability and complexity, and ultimately this is the cost, of the
structure you have placed in the flame/gas path will determine its future
usefulness. Interesting solution none the less.</div>
<div><br></div>
<div>Here is a recent video of my premixed blue tlud-gas flame. Its all
geometry, no obstruction.</div>
<div><a href="https://www.youtube.com/watch?v=jnV1e60NTss&feature=youtu.be" target="_blank">https://www.youtube.com/watch?<wbr>v=jnV1e60NTss&feature=youtu.be</a></div>
<div><br></div>
<div>Alex<br>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Sep 28, 2016 at 12:05 PM, kgharris <span dir="ltr"><<a href="mailto:kgharris@sonic.net" target="_blank">kgharris@sonic.net</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT:rgb(204,204,204) 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex" class="gmail_quote"><u></u>
<div lang="EN-CA" bgcolor="white">
<div><font face="Arial">Crispin and All,</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Some clarification: By radial mixing I
assume you mean the method in the lower photo where the air travels
inward, radially. By helical mixing I assume you mean swirling
gasses by using fan blades like in the top photo. Neither of
these represents a conclusion on my part. Your opening
sentence put me on guard immediately because it defines your techniques as
my conclusion. A more accurate starting sentence for your
response would have been 'Here are two techniques to look at that have
worked for me'. My thinking is not limited to these two
ideas. </font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Your techniques are what I was looking for, ideas for
rapid mixing.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial">Kirk H.</font></div>
<div><font face="Arial"></font> </div>
<div><font face="Arial"></font> </div>
<div><font face="Arial"></font> </div>
<blockquote style="BORDER-LEFT:rgb(0,0,0) 2px solid;PADDING-LEFT:5px;PADDING-RIGHT:0px;MARGIN-LEFT:5px;MARGIN-RIGHT:0px" dir="ltr">
<div style="FONT:10pt arial;font-stretch:normal"><font size="3">-----
Original Message ----- </font></div>
<div style="BACKGROUND-COLOR:rgb(228,228,228);FONT:10pt arial;font-stretch:normal;background-size:initial;background-origin:initial;background-clip:initial"><font size="3"><b>From:</b> </font><a title="crispinpigott@outlook.com"><font size="3">Crispin Pemberton-Pigott</font></a><font size="3"> </font></div>
<div style="FONT:10pt arial;font-stretch:normal"><font size="3"><b>To:</b> </font><a title="stoves@lists.bioenergylists.org"><font size="3">'Discussion of biomass cooking stoves'</font></a><font size="3">
</font></div>
<div style="FONT:10pt arial;font-stretch:normal"><font size="3"><b>Sent:</b> Tuesday, September 27, 2016 8:09 PM</font></div>
<div style="FONT:10pt arial;font-stretch:normal"><font size="3"><b>Subject:</b> Re: [Stoves] Rapid mixing</font></div>
<div><br></div>
<div>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Dear
Kirk<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">I
think your conclusion is correct – that you can shorted the height of the
combustion zone with radial or helical
mixing.<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">I
provide two photos with this in mind, though accomplished in completely
different ways. The first is (for a wood burner, not pellets) is to put
the mixed below the fuel, to continuously create a series of ‘induced
vortices’ a few of which pass through the fuel and provide mixing by
spinning. A vortex tends to perpetuate itself so all that is needed is to
get a few going all the time.<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><img style="MIN-HEIGHT:2.833in;WIDTH:3.145in" src="cid:09FB0192762A4BDA9EACFDD25FC626DC@phyllisPC" width="302" height="272"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">The
material is a low chrome stainless steel. The production is in three
stages: blanking, punching the cuts, then
forming.<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><font size="3"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt">The second method
of shortening the flame is to use the secondary air entering the fire as a
method of driving the flames horizontally. This should be done in a
‘divided’ manner, not a ring of air, so that it breaks up the rising gases
into manageable jets. This kind of short clean burn can only be done with
preheated secondary air – 300-500</span><span style="FONT-FAMILY:tahoma,sans-serif;FONT-SIZE:11pt">˚</span><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt">C works
well.<u></u><u></u></span></font></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><img style="MIN-HEIGHT:3.145in;WIDTH:3.145in" src="cid:55273154DB1C4F3FA2B12AA3BD463CD8@phyllisPC" width="302" height="302"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><u></u></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">The
fire above is burning pellet gas (as a TLUD) though it also works for wood
if the gas generation is consistent. Consistency requires very good air
control. The amount of is required to achieve this is so low that it
pretty much rules out having an open bottom with fuel sticking out.
<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Readers may recall Julien in Coburg combined the injection of air
and placement of the air feed in the gas stream. A problem commonly
reported with that approach is the cooling of the metal by the air can
interfere with the combustion.<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Readers may also recall Dr Nurhuda in Indonesia achieved a downward
turning flame consistently in his recent stoves reducing the flame height
basically to zero. All of these approaches can assist the provision of
lower height stoves – a major challenge for typical Indian rural
households where cooks won’t compromise on the cooking height.
<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Everyone should try these approaches and report what works well.
<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Regards<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><font size="3">Crispin<u></u><u></u></font></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<p class="MsoNormal"><span style="FONT-FAMILY:calibri,sans-serif;FONT-SIZE:11pt"><u></u><font size="3"></font><u></u></span> </p>
<div>
<p class="MsoNormal"> ……<u></u><u></u></p></div>
<div>
<p class="MsoNormal"><font size="3"><span style="FONT-FAMILY:arial,sans-serif;FONT-SIZE:10pt">Not to be
distracted from the purpose of this list, I have a thought about wood
stoves. A small natural draft wood burning cook stove that mixes the
wood gas with secondary air in 2 cm has a considerable advantage over
a stove that may take 20 cm or more. It's a little
like transistors, which gave advantage over vacuum tubes in
electronics. Rapid mixing can enable a small wood stove to burn
quick and clean at both <strong><u><span style="FONT-FAMILY:arial,sans-serif">high and low</span></u></strong>
power levels. Witness the excellent numbers for the Wonderwerk
TLUD-ND stove which uses a rapid Venturi mixing technique.
Combined with the user friendly power level controls, the principles
used in the Wonderwerk stove hold considerable potential. Rapid
mixing seems to me to be a very good area for research. I
wonder how many rapid mixing techniques will be found over the next
few years? I intend to
contribute.</span><u></u><u></u></font></p></div>
<div>
<p class="MsoNormal"><u></u><u></u> </p></div>
<div>
<p class="MsoNormal"><font size="3"><span style="FONT-FAMILY:arial,sans-serif;FONT-SIZE:10pt">List, keep writing
about wood stoves, don't be
distracted.</span><u></u><u></u></font></p></div>
<div>
<p class="MsoNormal"><u></u><u></u> </p></div>
<div>
<p class="MsoNormal"><font size="3"><span style="FONT-FAMILY:arial,sans-serif;FONT-SIZE:10pt">Kirk
H.</span><u></u><u></u></font></p></div></div>
<p></p>
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