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Re: a thermodynamics question



Martha Takats asks:
Here is a new (maybe trivial) question for all you thermodynamics buffs.
Our building just got the heat turned on. Unfortunately, due to recent
construction, none of the thermostats are working, so it's getting very
hot. My colleague in the next office can't open his window, so he is
cooling the room by running his air conditioner. Now the textbook air
conditioners remove "Qc" from indoors and exhaust "Qh" outdoors. Trouble
is the temperatures are Th = 50 and Tc = 80. What happens in this case?
Does the air conditioner generate electricity rather than consume it?

If the Air Conditioner were a 'Thermo Electric Module', then yes it COULD
generated electrical energy. These modules are used in 'ice boxes' designed
to operate in '12VDC'. Depending on which way you align the plug the box
cools or warms. The modules typically have a series string of 128 solid
state pn junctions with a low enough barrier voltage to allow ambient
temperatures to creat electron hole pairs which are swept away by the
electric field. Recombination at the opposite junctions produces the
heating effect.

For your freon driven AC, however, you just get real efficient 'heat transfer'.

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(919) 286-3366 x224 Albert Einstein, 1936