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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Dear Paul <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'>At some point Alexis changed from or was it to a premixed flame. A premixed flame is like what you get from a standard gas stove which entrains air in the gas in the long tube leading to the round burner. <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'>If the flame is premixed it is shorter.<o:p></o:p></span></p><p class=MsoNormal><b><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p> </o:p></span></b></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>You might write to Alexis to ask what the present configuration is. I know that he has too much excess air in the current models and it was caused by the switch from one to the other – I just can’t remember at this time which it was. The burner was created for, I think, an unmixed flame and he switched to premixed. That means the air supply for the flame should have been reduced the amount added in the premixing, leaving the flame in a high EA condition reducing the temperature and heat transfer efficiency.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Alexis demonstrated the new one at the Bangkok meeting for the GACC Roadmap.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><p class=MsoNormal>Stovers,<br><br>I have left below the previous discussion by Ron and me. And I thank him for his thoughtful comments. <br><br> But to keep things short, here is a reply to some issues raised (much snipped and with order sometimes changed:<br><br>1. Ron wrote: <o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><b>I think the diffusion process is substantially similar, in both normal and “inverted” flames. </b><o:p></o:p></p></blockquote><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><b>Are there other TLUD photos around I can look at, that show the flame appearing between secondary air holes - not over them?</b><o:p></o:p></p></blockquote><p class=MsoNormal>Inverted flames are conical just like regular flames. Looking downward at them, the parts that are over and below the air coming in are the thinnest and the flame can appear to be absent. But it certainly is there. Meanwhile, the parts of the flame on the two sides of the cone are seen as much more yellow because of looking downward through side-wall of the cone, which can appear to be "thicker." AND, because the sidewall flames of two adjacent inverted cones are close together, the flames are joined and appear to be attached to the walls of the fuel canister. <br><br>2. Paul A. Wrote: <br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal> In the TLUD gasifiers, the secondary air holes are sufficiently close together that the inverted flames are filling the space between the apertures of the incoming gas (which is actually air).<o:p></o:p></p></blockquote><p class=MsoNormal>I should have written ".... the incoming <i><u>NON-combustible</u></i> gas (which is actually air). " Sorry for the confusion. The INVERTED flame is still the mixing of two gases (air and combustible gas), but with the air in the center of the cone.<br><br>3. Alexis Belonio's most known stoves are with "natural flames" with the combustible gases being injected vertically into a zone of air, with his burners looking much like a regular burner of gas fuel. But Alexis was discussing with me the inverted flame situation, so my comment was correct when I wrote: <o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>And also, Alexis Belonio was advocating in January 2014 at the Aprovecho Open House about some form of spreading the gases that need to reach the secondary air that is coming in from the sides. <o:p></o:p></p></blockquote><p class=MsoNormal>Paul<br><br><o:p></o:p></p><pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD <o:p></o:p></pre><pre>Email: <a href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a> <o:p></o:p></pre><pre>Skype: paultlud Phone: +1-309-452-7072<o:p></o:p></pre><pre>Website: <a href="http://www.drtlud.com">www.drtlud.com</a><o:p></o:p></pre><p class=MsoNormal>On 5/3/2014 2:34 PM, Ronal W. Larson wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal>***** change of topic ***********<br><br>I comment on Ron's statement: <o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>By looking closely, counterintuitively, the flames seem attached NOT over the gas apertures, but rather between them. I think this is true in all cases but can’t see the case C “attachment” points. Except in private dialogs with Paul O, I have not seen this stated before in print - and don’t know if it should be encouraged or discouraged. <o:p></o:p></p></blockquote><p class=MsoNormal>I think this has been considerably discussed or at least observed. <o:p></o:p></p></div></div></blockquote><p class=MsoNormal><span class=apple-tab-span> </span><b>[RWL: If anyone can provide a link, that would be much appreciated. Paul Olivier and I never found a write-up - and it still baffles me. Are there other TLUD photos around I can look at, that show the flame appearing between secondary air holes - not over them?</b><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal>It relates to the phenomenon of the "inverted flame" in which the air enters a zone of combustible gases instead of the combustible gases entering a zone of air (which is the case of common gas burners on stoves. <o:p></o:p></p></div></div></blockquote><p class=MsoNormal><span class=apple-tab-span> </span><b>[RWL: Well, I think there is another explanation. Paul Olivier has his gas flamelets enter into air - not the "inverted flame”, which I agree is or could be substantially different. But the Olivier/Belonio flamelets (very short - not the typical long flames of most TLUDs) look remarkably similar to small match or candle flames. I think the diffusion process is substantially similar, in both normal and “inverted” flames. I think the results obtained by Jim Jetter showing low particulates and CO with many TLUD tests indicate the regular and inverted flames can’t be widely different. The emissions are arguably superior with TLUDs - and (maybe) independent of whether these flames seem to originate from over or between holes.</b><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal>In the TLUD gasifiers, the secondary air holes are sufficiently close together that the inverted flames are filling the space between the apertures of the incoming gas (which is actually air).<o:p></o:p></p></div></div></blockquote><p class=MsoNormal><span class=apple-tab-span> </span><b>[RWL: As noted above, I mostly operated with a continuous circumferential narrow slit - and never saw this - which is why I used “counterintuitively” Has anyone ever seen this with a natural gas multi-hole burner? My discussions with Paul Olivier centered on the importance of radiation - possibly coupled with the fact that pyrolysis gases have a chemistry (not try for methane) which gives you a smaller number of reaction particles at the end than going in. Makes for a helpful pressure difference. (This holds for whether there is gas entering air or air entering gas.)</b><o:p></o:p></p></div><div><p class=MsoNormal><span class=apple-tab-span><b> </b></span><b>Re the last clause <i>("which is actually air")</i> needs more discussion. There has to be some gas there in order to have a flame. If there were still eight input ports, but appreciably smaller, would we see the same thing? Does it have to do with a big air speed through the input ports?</b><o:p></o:p></p></div><div><p class=MsoNormal><span class=apple-tab-span><b> </b></span><b>I think there is a doctoral thesis lurking in here somewhere. There may be some optimum of hole diameters, spacings, shapes, separations, etc - to get the best flames (better “flamelets”).</b><o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><b>Ron<br><br></b><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><div><p class=MsoNormal><span class=apple-tab-span> </span><br>Paul A.<br><br><o:p></o:p></p><pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD <o:p></o:p></pre><pre>Email: <a href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a> <o:p></o:p></pre><pre>Skype: paultlud Phone: +1-309-452-7072<o:p></o:p></pre><pre>Website: <a href="http://www.drtlud.com/">www.drtlud.com</a><o:p></o:p></pre><p class=MsoNormal><o:p> </o:p></p></div></div></blockquote></div></div></blockquote><p class=MsoNormal><o:p> </o:p></p></div></body></html>