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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 and Frank<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><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>What exactly is the problem that you see that requires a (very) different type of solution? The proposal is, ultimately, mass-based. Mass-based calculations of fuel energy are plagued with problems because while you can get an answer for one type of wood (with a certain error bar) as soon as you move to another fuel like palm leaves or shells or rice hull then comparisons are not fair.<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>So perhaps the reason why stoves that make charcoal need special treatment should be clarified. All biomass stoves make some char and there are fair methods of dealing with it.<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I suspect the root question being asked is ‘What is the heat transfer efficiency?”<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you want to know that, then there are ways to find out.<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If you want to know how much fuel a stove consumes, either in mass of energy, there are also ways, and it gives an answer different answer from the heat transfer efficiency question.<o:p></o:p></span></p></div><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Calculating the mass of dry fuel equivalent that is the equivalent of the energy used to cook is not helpful. We already would know the energy involved. Dividing by the energy in that type of fuel just renders the final number incomparable with stoves that use another fuel. Leave it is Joules.<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Is the intention to find the heat transfer efficiency?<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thanks<br>Crispin<o:p></o:p></span></p><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></body></html>