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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 Kevin<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'>Wow. Well I had not considered either of those two. What is perhaps the logical approach is to look at the processes that could account for 100 g of gain.<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'>You can take it that the initial fire was with 5 kg of coal and then a reload with 4.6 = 9.6 kg of coal, 25% moisture, roughly 10% ash. From that we could calculate the missing fraction of fuel mass which would be most of the non-ash portion. I can’t see there being enough carbon left to pick up that much O<sub>2</sub>.<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'>There is no doubt that the reversal idea is not correct because there is a temperature record and the interior air temperature remained well above the outdoor temperature (the building is heated).<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'>Here is the set of temperatures with the Mass, test date 12 Jan 2010:<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><img width=680 height=319 id="Picture_x0020_1" src="cid:image002.jpg@01CE13DD.CC60A8F0"><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'>You can save and stretch that. The 1 deg rise in temperature to -12.5° as the sun comes up is visible at the end. The temperature in the stove is slightly higher than the air in the room. The mass curve is generally the same shape as the charts by Battacharyya for coal (with a different time scale – but remember this is coke).<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'>It was hardly an ideal set of measurements. We were just looking to see the cooling. The thermal efficiency of the stoves drops to -250% at times because it pulls in more cold air than it generates as heat – the fire just acts as a fan to throw heat from the room up the chimney.<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'>I am still prepared to write off the mass change as an instrument artifact – wind or something but it is a curious phenomenon to consider.<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'>Regards<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'>Crispin<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><o:p> </o:p></p><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>Dear Crispin</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>I can think of two possibilities for the possible weight gain:</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>1: If there was backdraft, as a result of the windy conditions, it might be possible that particles of char or creosote fell from the chimney, or were blown back, to the stove system, creating an increase in weight of the stove system. This material then burned off. Note that the weight at about 2815 is the same as at the very end of the chart, where the red line continues past 6567</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>2: The oxygen that was picked up would be not only as oxygen, but as CO2. What might have happened is that is that the ash, containing FeO could easily pick up oxygen and become oxidized to Fe3O4, and limestone components in the ash could have been calcined to CaO, which could easily react with CO2 from the atmosphere, to "airslake" back to CaCO3. The "jiggle in the weight" may be a result of "local fire" re-calcining" the lime fraction, or "re-reducing the iron components.</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>Any likelihood that either of these guesses might be accurate?</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>Best wishes,</span><span style='color:windowtext'><o:p></o:p></span></p></div><div><p class=MsoNormal><span style='color:windowtext'> <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:windowtext'>Kevin</span><span style='color:windowtext'><o:p></o:p></span></p></div></div></body></html>