Dick Frey, K4XU gave me permission to post his interesting insight (see below).
Dick is an engineer for a major semiconductor manufacturer. Probably the
chart won't make it through the mail list. Those who want it, please reply in
private.
Paul, W9AC
---------------------------------------------------------------------------------------------------------------------------
Paul,
Vapor-phase cooling is neat. Good ol' Alpha PA70V. If we reduce the pressure to
lower the boiling point of the cooling liquid (closed system - no evaporation),
you utilize the same heat of vaporization, transfer a lot of heat, but at a
significantly lower temperature. This is already being done with heat pipes.
Heat is heat. Whether we make it with tubes or transistors, we have to move it
and dissipate it. The fundamental difference between tubes and transistors is
their operating temperature. Transistor are also more dense, smaller with
higher W/cm³. You need an efficient sink. Here's the chart for water:
Pumping the cooling loop pressure down to 1 psia makes the water boil at 100°F.
The heat moves just as well. Keep the condenser/radiator above the heat source
so the water can return to the sink by gravity. You still have to move that
heat to the ambient environment. If that is your shack, better open the window,
or use a big bucket of cold water and a heat exchanger.
Food for thought.
73,
Dick
_________________________________________________
Richard Frey, P.E. K4XU
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|