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<div class="moz-cite-prefix">Kirk,<br>
<br>
<blockquote type="cite"><font face="Arial" size="2">Also I note
that as the fire rises, it narrows and comes to a point,
meaning that it is accererating. <br>
</font></blockquote>
<font size="2"><font face="Arial">Perhaps. But it also can mean
that there </font></font>is insufficient mixing, resulting in
the central part needing more time and height to reach to air with
oxygen.<br>
<br>
I like your example about the boulder. I agree that VERY little
pressure difference is needed.<br>
<br>
Paul<br>
<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 4/21/2014 12:40 PM, kgharris wrote:<br>
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<div><font face="Arial" size="2">Hi All,</font></div>
<div> </div>
<div><font face="Arial" size="2">Thoughts on buoyancy have been
grinding around in my head, and I have had some good ideas for
experiments. I have not been able to work with these because
of another situation. I sent a TLUD with turn-down capability
to Aprovecho for testing, but they were only able to get a
turn down ratio of 1.7 to 1. I was able to get 3.3 to1 before
I sent it. My assumption is that during shipment some of the
sealant broke off and the stove is leaking too much air into
the reactor. Now I am building a stove which does not require
so much sealing by moving the primary adjustment from the
outside directly to the bottom of the reactor. It is a plate
of metal that can cover the bottom of the reactor and can be
pivoted down to allow adjustment of the air flow, thus
eliminating several potential leak points. This is a major
redisign and is taking some time.</font></div>
<div> </div>
<div><font face="Arial" size="2">My first thoughts to the
responses to my earlier writing about buoyancy was to be
sceptical of what was said. I could not believe that anything
smaller than .01 inches of water column could drive a fire the
size of what I see comming out of our TLUDs. Further thought.
has given me a mechanism which might be able to do this.
Pushing a boulder takes a lot of force. One must overcome
both inertia and friction. If the boulder was made of
styrofoam it would take a lot less force because the lighter
material has less inertia and friction with the ground. The
fire gasses are very hot and of VERY low density, so very
little force is required to move them. Also, unlike the
boulder, the friction forces are close to zero. These two
things could allow a tiny push from the air to move the fire
gasses, and buoy them up. </font></div>
<div> </div>
<div><font face="Arial" size="2">Also I note that as the fire
rises, it narrows and comes to a point, meaning that it is
accererating. If the fire could be kept slower in the
combustor, then the combustor could be shorter, thus possibly
getting a better burn with a shorter stove. Dr. Larson has
been talking about making shorter stoves for safety reasons.
The down side I see is that at Aprovecho I learned that heat
transfer into the pot is improved by a fast fire which can
penetrate the surface layers of air under the pot. Slowing
the fire down might counter this effect. </font></div>
<div> </div>
<div><font face="Arial" size="2">Kirk H.</font></div>
<div><font face="Arial" size="2">Santa Rosa, CA. USA</font></div>
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