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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'>Interesting perspectives.<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 was involved in a very brief attempt to build a small steam engine in Swaziland with a guy who had been trained ‘old school’ and knew how to design one. A heat engine is not necessarily as inefficient as a hot air engine, however. Because the working fluid can be something other than steam, and because the heat released during condensation does not happen with an expending and contracting gas, there are some pretty big efficiencies available. Stirling engines (which are supposedly hot air engines) can be run with compressed Helium and get high efficiencies.<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'>A thermoacoustic refrigerator is a type of Stirling engine. The ones designed by Los Alamos labs these days are 45% efficient at 150 kW. They use helium as a working fluid at about 15 bars I think. That is higher efficiency than a diesel engine, but it moves heat, not generates shaft rotation.<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 is however an externally fired ‘heat engine’ (with a resonant frequency of about 40 Hz).<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><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'><o:p> </o:p></span></p><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Dear Crispin</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Sadly, many "Boiler and Steam Regulations" are an unfavourable collection of Bureaucracy, Conservatism, and Obsolescence." The cruel fact is that many boilers have exploded in the past killing many people, due to incompetence, poor design, lack of attention, poor controls, etc. 'the Laws of the Day" were made to "plug the holes." A good steam plant is a great way to head building complexes, and only low pressures are needed. Steam Power Cycles typically use the Rankine Cycle, and it demands high temperatures and high pressures for efficiency.Most steam Power Plants operating at below 500 PSIG are considered obsolete. A "Steam power Plant" running on 15 psig steam (2 bar) can generate shaft power, but will be dreadfully inefficient. A 4 bar plant (60 psig) is much better, but still well within the "Dreadful Efficiency Class"</span><o:p></o:p></p><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>One cruel reality of steam is that it is a great concept, but surprisingly complex in practise. Another cruel reality about steam is that there are a lot of encumbering laws and Regulations associated with it. One can find ways to evade the regulations, and this is OK, until there is an accident. That's when</span> <span style='font-family:"Arial","sans-serif"'>the Boiler Inspector has a Field Day. </span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>As a General Concept.... "There is no way that one can sensibly generate shaft power with small steam engines, because of dreadful system efficiency. However, there may indeed be sensible "small steam power" generating systems, providing there is a sensible use for low grade waste heat from engine exhaust. For example, a small steam engine system for driving air circulating fans in a Lumber Kiln, or a Greenhouse.</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Hot air engines would have approximately the same engine efficiency as would a steam engine having steam entering the engine at a temperature similar to the temperature of the hot air entering the "Hot air engine system."</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Best wishes,</span><o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal><span style='font-family:"Arial","sans-serif"'>Kevin</span><o:p></o:p></p></div></div></body></html>