User talk:Archimerged

I expect to be doing more work on wikicities than on Wikipedia, so I might notice messages here sooner than at my User talk page on Wikipedia.

Heat pipe question
Why can't I build a heat pipe from Death Valley up the nearby mountain and so get a fairly large delta-T at the top of the mountain? Or from the bottom of the Homestake mine to the top of the nearby mountain?

I suppose it has to do with insulation efficiency. The theoretical heat pipe is evacuated and perfectly insulated, filled with the right amount of refrigerant so that condensed liquid runs downward (perhaps in a separate small drainpipe to keep from cooling the vapor) and vapor at the hot temperature moves quickly to fill in the space vacated by condensed vapor. Condensation only occurs at the top of the mountain, not along the mile or two long pipeline leading from the hot location up the mountain.

Actually, I guess the problem would be reasonable cost insulation cannot prevent continued condensation below the top. How do I calculate this? I guess I know: look up the coefficient of heat transfer for various types of insulation, figure the actual area of pipe needing insulation, and figure how much heat will leak out along the way to the mountain top.