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<div class="moz-cite-prefix">Crispin, Julien, Joe,<br>
<br>
A few weeks ago a message (below) from Crispin contained this
message:<br>
<blockquote type="cite">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">@Paul
S Anderson, what do you think of us putting together a chart
with a diameter/flow plot for different levels of draft? <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
</blockquote>
Although such a chart might be interesting, it is a bit beyond my
comfort level, and the work would fall to people with such
abilities, such as Crispin, Julien, and Joe. I am not able to
"appreciate" it enough, and I am not sure how it would be used in
improving cookstoves. But I and many others are all open to
further discussion.<br>
<br>
Paul<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>
On 7/23/2014 6:07 PM, Crispin Pemberton-Pigott wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Dear
Julien<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">This
is a good and helpful report with a lot of practical
experience built in.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">On
slide 7 it says “However, heating air decreases its density,
so air velocity must increase to maintain the quantity of
oxygen mixing with pyrogas.”<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">It
is probably worth mentioning, because it is against common
sense, that increasing the temperature reduces the density
but increases the viscosity. Getting the right size hole is
not quite as simple as a pro-rata change in area. That plus
of course the shape of the entry hole changes the flow (a
lot). <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">@Paul
S Anderson, what do you think of us putting together a chart
with a diameter/flow plot for different levels of draft? <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Question:
In slide 18, it gives the burn rate per unit time per unit
volume. I can’t grasp that easily. Is the density somehow
detectable in there? What is the mass loss rate in g/minute?
While I realise that meaningful interpretation requires
knowing the volume of fuel involved, I was trying to
calculate the water mass out of the burn rate to see what
the ‘real burn rate’ was. It is difficult to do that as the
mass per unit time is not the metric.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Is
there some other way you can report the burn rate for
different fuel moisture levels?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">It
would be helpful, if you stick to the mg/minute/cm<sup>2</sup>
and first factor the mass loss raw data for the moisture
content so it is mg<sub>DRY</sub>. In that way we can
calculate the fuel burn rate and then, using the moisture
level, calculate the true realisable energy (potential)
value.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Performing
this calculation sometimes gives surprises. From the look of
the curves, the energy available drops as well as the burn
rate. This is intuitive but not always the case. One thing
to take a lesson from is the investigation which shows that
15% moisture fuel usually has lower PM emissions in most
devices than 10% or 5%, but increasing it above 15% more
sees the level rise. For each stove type there is an
optimum. <o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">For
the TLUD’s with a different burner design, there is probably
a different optimal moisture level.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Thanks
for sharing the presentation.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Crispin<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">Hi Stoves;<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">In May, I reported to this listserv on
some tests I had done with a menagerie of gas burners.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/2014-May/008665.html">http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/2014-May/008665.html</a><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">My tinkering has continued, and some
results are attached as a pdf that show some interesting
features of ND-TLUDs. For example, the best I could do
for a turndown was about 2x, and turndown is very
sensitive to primary air supply.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">These tests follow from the earlier
work were is was shown that placing a concentrator disk
below the secondary air inlets did not result in a flame
concentrated above the aperture in the disk. Instead,
pyrogas moved radially outward to the underside of the
secondary air holes, and became entrained in the jets of
secondary air. <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">In addition, I was using gas burners
that were 1.2 x larger than the diameter of the TLUD
combustion chamber so as to get more space to manipulate
secondary air, and more space for the gas flame to
develop. This work suggested that is was possible to
increase the diameter of the gas burner even further. The
current trials put this to the test. Here is an abstract
of the study:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">ABASTACT<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Gas burners for a natural draft,
top-lit updraft gasifier (ND-TLUD) were assessed for
visible flame characteristics and their effect on
gasification rate. Two main design options were tested:
diameter of the burner and preheating secondary air.
Burners were tested on wood chip fuel that varied in
moisture content, and primary air was adjusted to get very
low to maximal rates of gasification. Preheating
secondary air had no visible effect on the gas flame nor
did it alter gasification rate. Increasing the size of
the gas burner from 1x to 1.2x the diameter of the TLUD
significantly improved gasification rate, reduced flame
height, and reduced visible smoke production. Further
increasing burner diameter to 1.5x TLUD diameter didn’t
cause a further increase gasification rate, and made the
reaction unstable at low rates of primary air and high
fuel moisture contents. Increasing the diameter of
burners to at least 1.2x looked very promising for
improving TLUD operation. Burners of 1.5x may be suitable
for TLUDs that only run at high gasification rates.
Larger diameter burners will likely cause less air
pollution, and should be tested for CO and particulate
emissions.<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">Increasing the size of gas burners
could be tested with some of Jock Gill's ideas for
increasing flame temperature in the burner.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><a moz-do-not-send="true"
href="http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/2014-May/008843.html">http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/2014-May/008843.html</a> <o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">All the best,<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">Julien.<o:p></o:p></p>
</div>
</div>
</div>
<br>
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