Inexpensive air driers?

[Notch1988]

Originally Posted by theastronaut

Here it is guys. Its a dorm fridge with a 5 gallon bucket of water inside, and 20 feet of copper tubing coiled inside of the bucket of water. The cold water cools the air line so that the water vapor can condense and be caught by the water trap on the outside of the fridge. I've got it connected with quick disconects so I can move it if I need to. Works great! I haven't had any problems with contamination since I started using it.

The only question I have is... why the bucket of water? Technically, the water inside the fridge will never be as cold as the air inside the fridge. Why not just leave the coil of copper open to the air inside the fridge? Seems less efficient having to cool the air and then the air has to cool the water. I'm no engineer or anything so if I'm missing something please explain...