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<body class='hmmessage'><div dir='ltr'>Thanks a lot, Lanny.<div><br></div><div>Very usefull, now we can tune the ND gasifier more accurate to fit diffrent types of biomass and sizes of fuel.</div><div><br></div><div>Do you have any experience or comments of the venturi effect?</div><div><br></div><div>Otto<br><br><div><div id="SkyDrivePlaceholder"></div><hr id="stopSpelling">From: lannych@bellsouth.net<br>To: stoves@lists.bioenergylists.org<br>Date: Sun, 14 Apr 2013 13:51:18 -0400<br>Subject: [Stoves] Airflow For Biomass Fired Appliances- Natural Draft Stoves<br><br>
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<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">I am going through my stove notes while I am sitting here!
</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">It will be a couple of weeks before I can work, so you may have to
suffer my stove topics a little longer. <span style=""> </span>Smile</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">I am putting together some thoughts about natural draft and
combustion airflow. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Do you see anything that needs to be corrected or expanded on, or
added? Other than grammar/spelling.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">I would like to avoid words and terms that can not be understood by
the average person or someone not good with
English.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Your criticisms and comments are appreciated.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"></font></span> </p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><strong><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span><span style="FONT-SIZE:18pt;"><font face="Calibri">Airflow For Biomass Fired Appliances- Natural Draft
Stoves.</font></span></strong></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Good combustion airflow is important for natural draft cookers, but
the air pressure from natural draft is very low. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Restrictive airflow paths in a stove can be a problem for air
volume and for getting combustion air to the best place for clean
combustion.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Draft and airflow:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Draft is important for natural
airflow:</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Draft is like reverse gravity, hot air flows
up.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Heat powers the draft, the more heat, the more air
flow.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Draft height effects air flow. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Heat can be siphoned or moved around a cooker like water can
be siphoned, if there no leaks in the stove.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Restriction reduces airflow for natural draft
designs:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">The more turns, or changes in direction you have, the more
restriction you get.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Quicker the turn, more the
restriction.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Smaller the holes, more the
restriction.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Chaotic air flow creates more
restriction.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Losing the momentum of the airflow through the system can reduce
airflow.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Restriction can increase air velocity which can be good at the
right place.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Restriction of the air flow can be used to limit excess
air.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Restriction of combustion air can be used to control the
fire/heat.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Things that help
airflow:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Fewer changes of direction. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Longer turn radius for the air flow</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Pathways that are less restrictive than small
holes.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">An orderly flow path with less turbulence helps air
flow</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Momentum or a continuous flow without starts and stops helps
airflow.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Air flow and clean
combustion:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">The flow path needs to lead to the place where the combustion air
can best be used.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">There should be enough velocity to mix the gases and possibly blast
fuel. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">The combustion air needs to be focused on the combustion zone in a
way that shortens the flame height. More like the way a TLUD with a fan works.
</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Flames should be complete before touching a surface, like a pot or
a griddle. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Air flow and excess air:
</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Excess air needs to be minimized; </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Unnecessary air dilutes the heat and carries the heat away with the
exhaust.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Air flow and “radiant
view”:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Air flow can be used to shorten flame height which puts the fire
closer, where there can be a larger radiant view.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">The larger the “radiant view” of the pot to the radiant heat source
the better. </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><strong>Air flow and Stove
construction:</strong></font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Focused airflow can shorten flame height so you can use a shorter
stove body, less materials to build the stove, and less materials to soak up the
heat, and less surface area to loose heat.</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"> </font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri">Lanny Henson</font></span></p>
<p style="LINE-HEIGHT:normal;MARGIN:0in 0in 0pt;" class="ecxMsoNormal"><span style="FONT-SIZE:18pt;"><font face="Calibri"><span style="FONT-SIZE:18pt;"><font face="Calibri">Criticism is the friend of correctness and the enemy of foolishness
-LH</font></span></font></span></p></div>
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