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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Yes, a TLUD would have a lot less soot. Charcoal stoves too. <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 message from Todd Albi mentioned a Turbopot, whose website I just checked out. It also claims fantastic results. Who knew there were all these finned pots out there?<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'>Dale<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 style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Stoves [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Tom Miles<br><b>Sent:</b> Sunday, July 28, 2013 2:27 PM<br><b>To:</b> 'Discussion of biomass cooking stoves'<br><b>Subject:</b> Re: [Stoves] Cajun Rocket Pot<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Is a TLUD likely to have less soot buildup on fins?<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'>Tom<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 style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Stoves [<a href="mailto:stoves-bounces@lists.bioenergylists.org">mailto:stoves-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Andreatta, Dale A.<br><b>Sent:</b> Sunday, July 28, 2013 11:12 AM<br><b>To:</b> Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] Cajun Rocket Pot<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I like 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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>As some of you know, I spent a lot of time around 2007-2008 working on finned pots, and never really got them to work well. I didn’t try this type of “pin fin” design because I couldn’t figure out how to make a prototype. <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'>With this pin fin design (that’s what mechanical engineers call this shape of fin) you increase the heat transfer area, but unlike the fins I worked with, you don’t significantly change the flow of the gas. You get high convective heat transfer coefficients. Hot gases impinging on a surface (hitting the surface from a perpendicular direction) usually gives better heat transfer than hot gases flowing parallel to a surface. The basic tests that have been done prove this, at least with industrial fuel flames. <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'>I expect that with a sooty flame, you could use a brush to scrape off most of the soot, and what you don’t get this time you can get next time. Thin layers of soot wouldn’t have much effect. Perhaps arranging the fins in rows rather than circular arrays would make them easier to clean quickly. <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'>I expect that emissions per unit of time will increase, since you are quenching the flame more quickly at the bottom of the pot and stopping the reactions that would otherwise burn up some of particles and CO. The effect might be small or large. On the other hand, if the time to boil is greatly reduced, the total emissions might be a lot less. <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'>I expect that you could make a pot out of cast aluminum with the fins cast in place. You could use tapered pins to save material and improve castability. You could probably also use sophisticated welding techniques, as has been described, or possibly furnace brazing techniques. <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 material of the pot doesn’t make much difference. Since all metals are much better conductors of heat than gases, it doesn’t matter whether the metal is much better at conducting (stainless steel) or much much better at conducting (aluminum). It would mostly then be a cost and manufacturing issue. <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 fins must be bonded (welded, brazed, soldered, cast in place) to the pot itself, otherwise there is too much resistance to heat transfer across the interface. <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'>What to do next? Where does one get one? If I can get a sample I could test it out on a variety of stoves, rocket, charcoal, open fire, gasifier, LPG, fire-in-a-bucket, etc. I could prepare a quick report by the next ETHOS time. Or, someone who does experimental work full time, such as Apro or many other labs, could do a better job in less time. What I’m saying is that this is a very exciting development, that could make a huge difference in what we do. We should pursue this quickly.<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'>Dale Andreatta, Ph.D., P.E.<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'><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 style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Stoves [<a href="mailto:stoves-bounces@lists.bioenergylists.org">mailto:stoves-bounces@lists.bioenergylists.org</a>] <b>On Behalf Of </b>Dean Still<br><b>Sent:</b> Sunday, July 28, 2013 11:36 AM<br><b>To:</b> Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] Cajun Rocket Pot/ capacitive discharge stud weldie<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Hi Lanny,<o:p></o:p></p><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>We tested a couple of pots with fins but the space between the fins clogged up quickly with soot, a good insulator.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Best,<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'>Dean<o:p></o:p></p><div><p class=MsoNormal>On Sun, Jul 28, 2013 at 5:21 AM, Lanny Henson <<a href="mailto:lannych@bellsouth.net" target="_blank">lannych@bellsouth.net</a>> wrote:<o:p></o:p></p><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Lanny have you seen capacitive discharge stud welding?<o:p></o:p></p></blockquote><p class=MsoNormal style='margin-bottom:12.0pt'><br>Yes I have a stud welder but I did not realize it would weld dissimilar metals especially aluminum to anything else.<br><br>Stud welding is very finicky and will leave a blemish on the opposite side of thin metal.<br><br>When a stud weld fails you have to grind the surface to clean it up before rewelding.. How are you going to do that if it is between the other studs?<br><br>Attaching studs, fins or anything to a pot is going to be problematic, but attaching something to the pot holder may be practical. The heat transfer may not be as good as having something attached to the pot but it could possibly improve the heat transfer.<br><br>Lanny Henson<br><br>----- Original Message ----- From: <<a href="mailto:ajheggie@gmail.com" target="_blank">ajheggie@gmail.com</a>><br>To: "Discussion of biomass cooking stoves" <<a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a>><br>Sent: Sunday, July 28, 2013 5:23 AM<br>Subject: Re: [Stoves] Cajun Rocket Pot<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>[Default] On Sat, 27 Jul 2013 20:48:02 -0400,"Lanny Henson"<br><<a href="mailto:lannych@bellsouth.net" target="_blank">lannych@bellsouth.net</a>> wrote:<o:p></o:p></p><p class=MsoNormal>I like creative people and take no pleasure criticizing their work but it is going to be too expensive and difficult to make with all the pegs.<o:p></o:p></p><p class=MsoNormal><br>Lanny have you seen capacitive discharge stud welding? This would<br>allow welding of dissimilar metals to the pot in any pattern. I have<br>no idea of costs.<br><br>Have you done heat transfer tests with your 4mm aluminium pot compared<br>with the thinner stainless one? Stainless is a notoriously poor<br>conductor of heat and theoretically would need to be just under a<br>tenth of the thickness of aluminium for the same conductivity, but I<br>do use stainless pots at home.<br><br>Finally can you explain the difference between a vat and a pot?<br><br>Paul I do consider this to be important because biomass stoves have an<br>inherent problem with heat transfer compared with natural gas or LPG<br>so improvements in heat exchange will have high benefits.<br><br>AJH<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><br><br><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br><a href="mailto:stoves@lists.bioenergylists.org" target="_blank">stoves@lists.bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org</a><br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br><a href="http://stoves.bioenergylists.org/" target="_blank">http://stoves.bioenergylists.org/</a><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div></div></body></html>