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</o:shapelayout></xml><![endif]--></head><body 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 Marc<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'>Thank you for reporting your progress. Not everyone does that.<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><div><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif;color:#1F497D'>></span><span style='font-family:"Calibri",sans-serif'>I achieved that just increasing the chimney height (about 175% of the reactor's height) and, following Crispin's notes: opening more secondary air holes below the surface of the fuel bed. I suppose this creates a some type of "pilot flame", as say Kirk, keeping high temperatures in the charcoal's surface, and thus, maintaining the flame in the transition phase.<span style='color:#1F497D'><o:p></o:p></span></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'>It has the advantage of lighting faster as well. When the flame lives close to the fuel it heats the fuel more rapidly by radiation. <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><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif'>I still don't know if this result is enough reliable and replicable, as I used the fuel itself as the main element of the control of the air flow (Crispin said) and the used fuel (almond husks) is far from being homogenic and predictable (particle size varies from 5mm to 5cm)<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='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'>I suggest you rattle the container well before each burn. Then it will settle as much as possible.<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><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif'>Note to Kirk : it didn't work for me the "basket method" proposed by Julien. Maybe it can work for others fuels and other drafts, as I only tried it once with a shorter chimney (about 100% of the reactor's height)<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='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'>Personally I don’t think a ratio is a good design approach. You need a certain vertical space to burn the gases before you attempt heat transfer. A total of 125-150mm is normally OK assuming you have the fuel deck covered with secondary air and it is burning hot near the fuel bed. If you bleed in secondary air through a lot of small holes, there will be no secondary air in the middle. Some try to compensate for this by putting in a vertical tube. That tube is a sign that he secondary air entrance has not been handled correctly. It is a common ‘solution’ to a problem that should not be there in the first place. Try to avoid it.<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><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif'>What I want in this case is: to heat an light-mass earth oven, with mininum attend to the fire, fast temperature gain at the begining, keeping constant temperature at about 200ºC, and maximum time of use (and, of course, smokeless and clean!). In this very specific case, I choose to burn the charcoal, as I gain about 50% more time to cook and don't worry about refuelling the reactor.<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='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'>In that case you should continue with the current layout, meaning where the secondary air holes. I have an extra 3 x 8mm holes low on the side of the fuel chamber to maintain a pilot flame no matter what happens with the fuel. <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><div><p class=MsoNormal><u><span style='font-family:"Calibri",sans-serif'>Some bad smells</span></u><span style='font-family:"Calibri",sans-serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif'>Although no visible smoke was produced in the process, it did some bad smell. <span style='color:#1F497D'><o:p></o:p></span></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'>The smell is most likely condensed volatiles that did not get burned. Before you do anything else, get the combustion looking good. See the message today to Saloop. It all applies to your stove as well. After you have the flame correctly places, then we will discuss smell. There may be none at all because the cause is poor mixing or too much secondary air.<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><div><p class=MsoNormal><u><span style='font-family:"Calibri",sans-serif'>Last smoke to remove</span></u><span style='font-family:"Calibri",sans-serif'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif'>At the very end of the process, when the char has been already pirolised and very little lefts, I had smoke. It was a different smoke, very light and odorless, and lasts about 2 minutes. <span style='color:#1F497D'><o:p></o:p></span></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'>It is still smoke and is most likely high in carbon. It means the flame went out or went out over a portion of the surface. I need to know more about the times involved – when the char started to burn and so on – to say more.<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-family:"Calibri",sans-serif'>I suspect it is the last remains of CO gases, which are not enough to mantain the flame. <span style='color:#1F497D'><o:p></o:p></span></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'>Excessive air from all sides can put out the fire by cooling it. It definitely had high CO in that condition.<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-family:"Calibri",sans-serif'>Maybe the solution is to open a third layer of secondary air entrance very near to the bottom, as Crispin suggested?<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><div><div><p class=MsoNormal><span style='font-family:"Calibri",sans-serif;color:#1F497D'>That can help. I suggest about 60mm above the bottom. Try it. You can always close it with a short bolt.<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<br>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></div></div></div></div></body></html>