I now proclaim that the "First Zaf's How It Works Contest" is open!
There will be a grand prize (trully grand...) for the person who will submit (in writting) the best explanation for how cooling machines work. By "Cooling Machines" I mean refrigerators, air conditioning, any kind of machine that "produces cold".
Here's a reason for the contest: More or less, everyone has some understanding of how you can produce heat at will, but cold? How can you produce cold? So, give it your best shot. Here are some terms you may find usefull in your research: thermodynamics, heat pump, freon, gas laws...
Submissions until the 26th of september... Submissions must be in .pdf, .doc or .rtf format. No links to ready-made explanations allowed. You must write your own. Have fun!