Hi A heat pipe might work if the fluid had a sufficiently low boiling point. The rubidium isn't terribly tolerant of high temperatures, and I'm going to pick up some heat rise as I put it inside some baffles / shields. You need to find something that fits a fairly narrow window.
I suspect that a recirculating water loop is a more practical approach to carry away the heat. It's got a pump to move the water, but the rest of it is fairly simple. Bob On Dec 24, 2009, at 2:49 PM, Joe Gwinn wrote: > A dodge occurs to me - a homebrew heat pipe: > <http://en.wikipedia.org/wiki/Heat_pipe>. > > Make the cold plate of copper, to which is soldered a meandering piece of > copper tubing, which tubing is also soldered to a copper radiator plate that > is above the coldplate, forming a closed loop with a fill tube attached by a > T. Braze all tubing connections, as for freon refrigeration systems. (Soft > solder is too porous to work for the joints, but is OK for attaching tubes to > plates.) > > Insulate the two tubes running between coldplate and radiator plate from one > another. > > Put enough working fluid into the system to fill the tubing that is soldered > to the coldplate, but no more. Warm the system up so the vapor drives all > the air out, pinch the fill tube off and fold it back, and braze the end > shut. (It's not critical to get absolutely all the air out.) > > Making the radiator plate be above the coldplate (the boiler) implements what > amounts to an oldtime two-pipe water vapor heating plant. Vapor goes up one > pipe, condensed fluid returns via the other. I lived in a house with such a > system. The difference between a vapor plant and a steam plant is pressure: > the vapor plant runs below atmospheric pressure, while the steam plant runs > at or slightly above. > > Make sure that things are arranged so the returning fluid does not pool > anywhere but in the coldplate, or the heat pipe will bang like an old steam > heating system. > > There is a brazing filler metal intended for copper-to-copper joints that is > widely used for freon systems: > <http://www.uniweld.com/catalog/alloys/silver_brazing_alloys/phos_copper.htm>. > The zero silver phos stuff is adequate, cheap and widely available. While > copper-to-copper needs no flux, copper-to-brass does, so also get the flux. > Plumbing supply houses and welding equipment stores are likely sources. You > will also need a torch or pair of torches able to raise the tubing joints to > an orange heat in a reasonable length of time. > > Depending on the chosen working fluid, the cold plate temperature will not > rise above the boiling point of the fluid unless the system is too small (in > radiator heat removal capacity) to easily handle the 10 or 20 thermal watts > that are passing through. > > What fluid to use? Anything common and thermally stable that does not attack > copper. Alcohol (methyl or ethyl) and water are common choices, as are the > various freons. I bet acetone would also work. Anyway, one controls the > coldplate temperature by a combination of choice of working fluid and > internal pressure. > > > I have seen commercially made heat pipes for cooling Intel CPUs advertised, > but I don't know that these units can be adapted. > > Anyway, a heat pipe system will stabilize the coldplate temperature fairly > accurately despite variations in thermal load, has no moving or electrical > parts, and may be sufficient by itself. If not sufficient, it can be used as > the outer stage in a two-stage ovening scheme. > > > Joe Gwinn > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
