"Arbitrator" wrote in message
ups.com...


In this type of system, where the working fluid does not undergo phase
changes or significant changes of pressure during it's cycle, it would
be impossible for the working fluid to become warmer than the ambient
air temperature and still cool the ambient air. Doing so would violate
the 2nd law of thermodynamics. One of the many equivalent statements
of that law is by Clausius, which is "Heat cannot of itself pass from a
colder to a hotter body."

For this system, if the working fluid became hotter than the air and is
still cooling the air, then heat is passing from a colder to a hotter
body, thus violating the 2nd law.


Just to add to the confusion ....

When there *is* a phase change (i.e. water going from a liquid to a vapor
or visa versa) ... energy is consumed and is called the latent heat of
evaporation or, in the case of vapor to solid, the latent heat of
deposition. Whatever source provided that energy will become cooler. That
source could be ambient air temp, humans, whatever. It's why you may feel a
chill from a breeze on a hot, humid day when you are sweating or when you
first getting out of a hot shower. There are evaporative coolers made using
this principle although they are not as effective as AC units.

Eisboch