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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'>I tried once to build a tilted BLDD and it was a continuous disaster. It just doesn’t work properly. I used a cylinder and tilted it. What happens is that the bottom corner fills with non-burning char and ash. Hopeless. I went back to vertical cylinders and after a while got the combustion zone smaller than the fuel hopper with very good effect. <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 the other readers: Paul taught me something very important about experimenting. When I said something like, “Don’t do that it will do x,” he would immediately do it to see that it really did x. The principle is the independent investigation of truth. Take nothing at face value. Paul is a systematic experimenter. This is a good approach to any scientific claims: do the experiment yourself – check it out and see if the claim (in both directions) is valid. We found many ‘old saws’ were not true, or not true all the time, only in certain circumstances. <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'>There are dozens of ways to make a stove work improperly. Paul and I have tried all of them, I think. Paul told me that a TLUD fuelled with wood could not be refuelled. We were on the back patio of my home in Ezulwini Valley in Swaziland and he went off to do something, leaving a small TLUD can-stove running,. I fed in some wood vertically and it worked just fine. I continued to do so and it continued to run long after it should have gone out. Thus I proved to myself (and Paul) that TLUD’s can be refuelled but not too much at a time. OK, that was valuable and contradicted received wisdom. <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 those days we didn’t have any gas measuring instruments and had to work on observations. The big change was the building of the SeTAR lab by GIZ at U JHB and shortly afterwards, by the Asian Development Bank in Mongolia. That gave me (and all of you readers) access to high quality real time measurements of the operation of a large number of stoves and combustion systems factored and calculated correctly. The producers paid attention and that is why there are so many extremely clean burning stoves in Ulaanbaatar now. Many of them are TLUD’s.<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'>One of the great lessons learned was that there is no such thing as a ‘dirty fuel’. The wet lignite being burned in Ulaanbaatar was supposed to be the dirtiest fuel anyone had seen. Well, that was because they were trying to burn it in a cheap wood stove. Try putting diesel into your gas engined car and see what happens. The hardware has to match the fuel. Big surprise, eh? Imagine matching the stove to the wood pellets to optimise combustion. Now, put oak logs in it and blame the oak for being smoky. Makes no sense.<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 recent attack on kerosene is embarrassing. There are thousands of old and invalid published claims that the fuel is itself ‘dirty’. That is people blaming the fuel for the faults of the stove. Truly, in this day and age that is embarrassing. Jet fuel is filtered kerosene with antifreeze in it. <a href="http://en.wikipedia.org/wiki/Kerosene">http://en.wikipedia.org/wiki/Kerosene</a> So where are the long black trails across the sky from the ‘dirty fuel’? How long must we put up with this?<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'>Stovers, defend your territory.<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></div></body></html>