<div dir="ltr"><div class="gmail_default" style="font-size:small">Thanks, Crispin,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">You advice fits nicely into my overarching principle: "Keep it simple, stupid."</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">The bricks will be made out of whatever material is used locally, invariably high mass. The insulative mud is only a thin veneer spread onto the bricks by the women. </div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">If I understand you correctly, wouldn't it be advantageous to mud the exterior but not the interior. That would allow the bricks to quickly absorb heat, release less heat to the outside and therefore give back more of the invested heat to the fire chamber? </div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">The dung/char test won't work without modification as this stove is only designed to burn wood.</div><div class="gmail_default" style="font-size:small"><br></div><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Kevin</div><div dir="ltr"><i><br></i></div><div dir="ltr"><i>Kevin McLean, President</i></div><div dir="ltr"><div><i>Sun24</i></div><div><i><a href="https://sun24.solar" target="_blank">https://sun24.solar</a><br></i></div><div><i>Tampa, Florida, USA</i></div><div><i><span title="Call with Google Voice"><span title="Call with Google Voice"><span title="Call with Google Voice">+1 (813) 505-3340</span></span></span></i></div><div><br></div><div> <img src="https://docs.google.com/uc?export=download&id=13teZQbnv_6ek6JkEy-4n0yyUVTrl3M2W&revid=0B8zNcWsuiuj3N2RuVFFYL3EvdElxR1lDcm9QQVlaL0F4VnVFPQ" width="200" height="200"> <img src="https://docs.google.com/uc?export=download&id=0B8zNcWsuiuj3b3RmUG1jbnpVeVU&revid=0B8zNcWsuiuj3c3pzVjJGdXk5R0dGdXNuVlBUZlQvTnR1NDdRPQ" width="200" height="148" style="font-size:12.8px"></div><div><br><i><span title="Call with Google Voice"><span title="Call with Google Voice"><span title="Call with Google Voice"><br></span></span></span></i></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><br></div><br><div class="gmail_quote"><div dir="ltr">On Fri, Aug 17, 2018 at 6:45 PM Crispin Pemberton-Pigott <<a href="mailto:crispinpigott@outlook.com">crispinpigott@outlook.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span>Dear Kevin<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Mud is quite insulative without adding anything. Before assuming
<i>anything</i> please check to see if there is some advantage to having a lower density stove body (which will definitely be physically weaker) before recommending it. Make sure the amount of new fuel required to perform some task is consistently less before
assuming it is “better” in some way.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Many tests have shown that on average, a high density combustor core outperforms “insulative” chambers unless the cooking time is very short. The reason is that heat must emerge from the walls at
a high rate during the late fire cooling period. If this effect is achieved, the CO burns out more completely, the invested heat (some of it) is returned) and the char burns more completely.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>If the stove body is ‘insulating’ the gain in thermal efficiency is brief and only at the beginning, give or take a few Watts. Unfortunately an insulating body, even if it contains a large amount
of invested heat, cannot give it back to the fire chamber at a rate high enough to sustain the combustion as late or as long. Depending on the stove configuration, the efficiency gain for having a high density combustion chamber is about 1/12<sup>th</sup>
of value which is considerable: 26% v.s. 24%, for example.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>When burning dung the effect is far more noticeable to the eye, without measuring anything. The thing to check is how much ‘char’ there is in the large lumps of ash when the fire is out. Using a
high mass, dense brick lining for the chamber, it is possible to get dung to burn so completely that you will not find more than one piece of char the size of a pea after burning 5 kg of fuel. All that is left is a fine white ash.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>An example (including all drawings) of such a stove is available
<a href="http://www.newdawnengineering.com/website/library/Stoves/Kyrgyzstan/KG%20Model2.5/" target="_blank">
here</a>.<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span>Regards<u></u><u></u></span></p>
<p class="MsoNormal"><span>Crispin<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Stoves <<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>>
<b>On Behalf Of </b>K McLean<br>
<b>Sent:</b> Friday, August 17, 2018 2:05 PM<br>
<b>To:</b> <a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a><br>
<b>Subject:</b> [Stoves] Ash mixed with clay to mud in brick stoves<u></u><u></u></span></p>
<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">In Africa, we are teaching women to make rocket stoves out of 11 standard bricks and a piece of rebar. You can see it here, called a 3-layer stove: <a href="https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.google.com%2Fdocument%2Fd%2F1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y%2Fedit%3Fusp%3Dsharing&data=02%7C01%7C%7Cf927dbb0d7754fd5fc1808d6046c458f%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701260400084277&sdata=q3ZC6QPL34O6NXpg%2FqzGd5yz7Aj%2B%2BA64aN7AZ4YvyQw%3D&reserved=0" target="_blank">https://docs.google.com/document/d/1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y/edit?usp=sharing</a><u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><u></u> <u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Do any of you have experience mixing wood ash with clay soil to make the "mud" more insulative? The women like to mud in these stoves. We want to determine whether to suggest they mix ash into the mud.<br clear="all">
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<p class="MsoNormal"><span style="font-size:12.0pt">Thank you,<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Kevin<u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt">Kevin McLean, President</span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt">Sun24</span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt"><a href="https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsun24.solar&data=02%7C01%7C%7Cf927dbb0d7754fd5fc1808d6046c458f%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701260400084277&sdata=h9jZkm7w837YU3VnK7bQX%2BGLgGlD5dSBX07TX7YYLrU%3D&reserved=0" target="_blank">https://sun24.solar</a></span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt">Tampa, Florida, USA</span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt">+1 (813) 505-3340</span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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<p class="MsoNormal"><i><span style="font-size:12.0pt"><a href="mailto:info@sun24.solar" target="_blank">info@sun24.solar</a></span></i><span style="font-size:12.0pt"><u></u><u></u></span></p>
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