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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link="#0563C1" vlink="#954F72"><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 Kirk<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><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>></span><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>It occurs to me that you may be fixating on your created negative here. <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'>I am <i>really</i> sure I did not create the ‘negative’ here. I am trying to save you from spoiling a really good design in an attempt to ‘get a better number’ on an invalid metric from which there is no physical foundation. As Jiddu noted here, it takes another wise good measurement and divides it by a random number. In the case of your ‘Tier 3 rating’ for specific fuel consumption, it mislead you, apparently, into thinking that you ‘did not achieve’ what you should have.<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:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>></span><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Did you notice the high power indoor PM2.5? At 0.7345 mg/min it is very low, and that is a positive. <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'>Yes this is a good value, but it is a measurement relevant to indoor air quality. If I make your stove exactly half the capacity I would cut the emissions rate in half by producing half the emission mass. What does this prove? For practical purposes, the emission rate should be per MJ delivered into a pot so we know if we are getting somewhere with the performance. Better heat transfer, better combustion efficiency, whatever, if the amount of heat getting into the pot is more per unit of PM mass emitted, that is ‘better’.<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'>If you have a 10 kW stove that emits twice as much as your stove, then the ventilation rate of the kitchen should/could be increased by a factor of two. Then the exposure for the cook is the same. Thus it is not a useful metric to report the emitted mass per minute only, you have to show what you are getting accomplished for that result. If I made a stove that was half the power and has the same mass emitted per minute, are those stoves equal? It would take it twice as long to accomplish any task, but the ‘per minute’ rating would be the same. What do we learn from that about stove performance?<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:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>></span><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>Also, all other results are very good. When your test methods are ready I will be happy to test accordingly. Until then I can only show the quality of this stove by the current standards. I am looking forward to also show the quality of this stove by your standards, when available.<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'>The method you refer to as ‘mine’ is widely available and used in multiple projects and countries. It is used by the national standard for Mongolia. It was developed by experts from about a dozen developing countries over a period of three years. No one has to use it, of course. People can do what they want. What is important is using metrics that are valid indicators of something about the stove that is meaningful for some policy or purpose. <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'>PM mass emitted per minute assists air quality – either indoor or outdoor depending on where it is emitted. Airshed modellers use mass per minute as an input for either allocating an airshed’s capacity or to predict air quality under various weather regimes.<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'>Engineering numbers for stove performance usually pertain to an efficiency of accomplishing something, for example CO mas per MJ of energy delivered into a cooking vessel or a living space. In a similar manner, the amount of energy taken from the available source per MJ delivered into the pot of room is relevant.<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'>For user experience, the convenience of not working much to prepare the fuel, fast lighting, controllability and heat per sq cm in the pot are all important parts of the cooking experience. Cleaning, disposal of wastes and ease of maintenance are also on that list – nothing to do with the engineering numbers (except the heat flux).<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'>In Mongolia the national standard includes a number of metrics which the cooking stove market doesn’t seem to notice. One is the kw/unit volume of the combustion chamber which I though was pretty interesting. Basically it is a measure of how hard the system and materials are pushed. <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-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>></span><span style='font-size:10.0pt;font-family:"Arial",sans-serif'>This stove or one like it will be at Aprovecho for Stove Camp in August. You are all welcome to be there to examine and test it. You will find a good stove, described during testing as "rock solid".</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>I look forward to being about to build and or teste one this year. Thanks for your efforts. And again thanks for putting new ideas into the public domain. Not everyone is doing this. Some out of necessity (investors) some out of a generosity of spirit. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>It will be great if someone takes it to market and demonstrates the benefits it brings in a practical manner.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'>Best regards<br>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D'><o:p> </o:p></span></p></div></div></body></html>