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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Dear Kevin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I have had a look at all the videos and this looks promising.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I admit I cringe when I see obvious improvements that can be made with little effort so I will jump in with more advice.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The bands could be made in a way so they do not sit on the ground, or three bricks could protrude inwards so the ring sits on them. The idea is to get air under the ring towards the end of the fire.
This would increase the firepower whereas now it drops quite a lot as the fire goes inside the upper part of the ring.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">A problem might be created with this change is remnant glowing char on the bottom when the replacement fuel charge is pushed in. I would have on hand a flat sheet to use as a scoop to wipe the coals
out of that burn space. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">On top there is obviously too much cold air getting into the flames which it is worth changing. Instead of stacking bricks for a demo, can you make a brick+mud structure that encloses the fire same
for an entrance hole (liberally bigger than the ring and fuel height)? Above the ring where you push, the bricks can be made into a cylinder (polygon) so that the part of the stove now seem above the fuel and flames so there is a cylinder of brick. This will
shelter the flames from side winds, “through” winds, and create a chimney effect.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The chimney effect will draw more ait to the centre, clearly lacking in the current version.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">It like the ignition in the centre leading to an outward burning set of stalks. After it is all going well, the centre is air-starved. The way to feed air to the centre is have a relatively small
gap above the fuel on the near wide, and perhaps two additional holes on the other two thirds. With these inlets of restricted size (compared with now) and the chimney effect, it should bring jets of air to the centre. What you are looking for as you tune
the hole and gap sizes is a reduction in the height of the flames. If there is air getting in, the flames will shorten, generally. Long flames are an indication of inadequate air, especially in the centre.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">For sure you can build such a brick stove without any mortar at all just to see how it works in principle. If you plan the ring size and brick positions, you can create a top deck that will accept
the pot bottom with something small like a triangle of rebar to create the pot-stove clearance. I suggest 8mm bar to create the clearance.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">If the bar diameter is too small, you will see smoke emerging from the fuel entrance. If you get no smoke out the entrance, keep reducing the pot rest height until you do, then go up one step. Looking
inside the flame area, if you see the flames lounging around “reeling like drunkard” instead of being drawn up stiffly, and there is no gas emerging from the front, you have the perfect balance. Were you to measure the oxygen level in the exhaust past the
pot, then calculate the excess air level, you would find it is in the range of 125% -250%. Ideal would be 100%-125% for a simple stove. As it is, it is probably 500%-900%. If you can get it under control, it will speed your time to boil.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Stay well<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Crispin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Stoves <stoves-bounces@lists.bioenergylists.org>
<b>On Behalf Of </b>K McLean<br>
<b>Sent:</b> Friday, October 21, 2022 16:14<br>
<b>To:</b> ajheggie@gmail.com; Discussion of biomass cooking stoves <stoves@lists.bioenergylists.org><br>
<b>Subject:</b> Re: [Stoves] Cooking bands - Testing with wood - 42% more efficient than three stone<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">I don't think I shared <a href="https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2F5M4ntJi_JmY&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=QFPdMZwjNaNihFd6ORpQ%2B0zrwouXCdtpi%2Ba3HwTD6rI%3D&reserved=0">
this video</a> with this list. Some of the same principles are probably at play. This is a comparison of two piles of maize stalks. The traditional way of burning maize stalks in Africa is by lighting the pile on the side, as was done with the pile on the
left. The pile on the right was lit on the top. The difference in smoke is stunning.<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Oct 21, 2022 at 5:36 PM <<a href="mailto:ajheggie@gmail.com" target="_blank">ajheggie@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Good stuff Kevin, this must be a similar combustion to a Swedish Candle, a short section of trunk with multuple saw cuts axially toward the bottom.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Andrew<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, 21 Oct 2022 at 11:00, Kevin McLean <<a href="mailto:kevin@sun24.org" target="_blank">kevin@sun24.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Our testing shows that cooking bands boil water with 42% less wood than a three stone cookstove with a rock bed. Remember that rock beds make three stone cookstoves a third more efficient and reduce smoke
by more than half. <a href="https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0973082620302775&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=OG1Th8MyiU4IUGZWv%2FDCfokhcsBMTkXgTOoeMRnmNko%3D&reserved=0" target="_blank">
Here is that article</a>.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">THREE STONE W ROCK BED</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">5 litres of water</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">Time at which water boiled: 23 minutes.</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">Fuel used: 1.2kg.</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0cm"><img border="0" width="159" height="89" style="width:1.6562in;height:.927in" id="_x0000_i1026" src="https://lh3.googleusercontent.com/_euPbO3r0c5l3KczRAbIKflOnO5dIQ2J3s7yldeS8TOfgQszTdpnZYowgJ6NRSuAmR9b3_TPBg3RrK5GH8Qjf2mXq_oZJYy8pGHcb7Q-McDdA7RbtJTLUjkLti1KnSh1L0i3q0Zz7rJkgGChFA0mEXzKSDt0I8518haxVIay7oD1iVg5JtqptU3iNg"></span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">BAND</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">5 litres of water.</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">Time at which water boiled: 15 minutes.</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">Fuel used: 700g.</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black">Much less smoky than three stone with rock bed</span><o:p></o:p></p>
<p style="margin:0cm"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0cm"><img border="0" width="157" height="88" style="width:1.6354in;height:.9166in" id="_x0000_i1025" src="https://lh6.googleusercontent.com/VksVVTzfJWB0M5KnWZ6DyJWnFuAjElHzJaPZpTknVT9_S6IiNG0qnnlqdBQf-gllKBmb9MxPxZL3nGARDpoFTTbaTRvYqe-7Or5Txm50R4cuAjIV1rl2__Dv54zN_AM4vcl1PPrFU1WO_RsKroXamkWc_O40Z3ipJZ59cNpKb_UHbYKSjSzw9HrPVA"></span><span style="font-size:12.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">Cooking bands are also faster and less smoky. They do not require tending. Elephant grass stalks, maize stalks, bamboo and cassava stems can be used in bands. Biochar can be made. A pair of bands (20 cm)
costs around 1 USD. Bands with a 25 cm diameter work well in school kitchens.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt">I hope that others can test further. I worry that my guys may bring bias into their testing. And they have no training on testing. (Thanks to Norm Baker who intends to test bands with maize stalks.)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal">Kevin McLean<o:p></o:p></p>
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<p class="MsoNormal">Sun24.org<o:p></o:p></p>
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