How do heat engines, refrigerators, and air conditioners work?

[misskitty]

Could someone explain to me how heat engines and refrigerators and air conditioners work. I'm very confused about the process and if they are isothermic, isovolumetric, or adiabatic.

~Kitty

 

[russ_watters]

The key to a refrigeration cycle is a working fluid with just the right properties that it cools down to a useful temperature when undergoing adiabatic expansion. Then, after going through a heat exchanger in gaseous form (dispensing its "coldness" to whatever use you have for it), warming it up, it is compressed into a much hotter liquid, and run through another heat exchanger, cooling that liquid down.

http://home.howstuffworks.com/refrigerator4.htm

 

[misskitty]

This just keeps doing that over and over right?

~Kitty

 

[russ_watters]

Yep: Expand (and cool)-> Pass through heat exchanger (and warm) -> compress (and warm more) -> Pass through second heat exchanger (and cool) -> Repeat.