<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Dear Ron<div><br></div><div>I am wondering if the term 'heat pipe' is being used correctly here. I certainly know what a heat pipe is but the vacuum tube collectors used in these solar installations are not heat pipes. They are what is described in the text. </div><div><br></div><div>They are vacuum insulated collectors being used in thermosiphon systems. The Mercedes cookers used a second thermosiphon to transfer heat from the main tank. That was not a heat pipe either though using a different working fluid it certainly could have and it might have solved the heat transfer rate problem. </div><div><br></div><div>In my view that combination might be the best way to get solar cookers much more widely used, tackling the institutional market first. It allows the heart be collected any time, and the cooking to be done later. The heat pipe is the correct technology to draw the heat to the cooking vessel or surface. By varying the pressure in the tube the heat transfer rate can be controlled. </div><div><br></div><div>Regards </div><div>Crispin </div><div><br></div><div>PS re the firewalled papers: you can write to the author and ask for a copy and they usually send it.</div><div><br><hr><div><b><br></b></div><br><div>Crispin and list:</div><div><br></div><div> Thanks for the updated cite. Makes at least two that are not behind paywalls. Hope we can find some that are even more current and easy obtainable. But there is a big literature on heat pipes outside the cooking arena.</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>I think we can learn a lot from the solar cooker side - but my interest is on biomass stoves and the ability to feed multiple pots from a single flame. You talk also about thermo-siphoning and pumps. I am describing neither of those - a heat pipe operates on a very different principle as I know you know.</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>The word “diode” is important here.</div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>I talked with one of the last references in your cite - Mr. C J Swet at about the time he wrote that 1974 article - on (I recall) a thermo siphon principle.</div><div><br></div><div>Ron</div><div><br></div><br><div><div><br></div></div></div></body></html>