Posted 06-10-2004 at 22:29:49
[Reply] [No Email]
I was gonna suggest flip the plug over on your electric blanket but naww!:)
BTW, do you know what the astronauts use to keep their suits cool on EVAs? They pump stale air thru them! No kidding! The suits have tubes thru them, and they pump stale air thru a vortex tube in their backpacks.
The thing works by compressing some of the air and then quickly releasing the rest. The compressed air will heat up by friction, thus drawing any heat fom itself, and as soon as it travels freely, it will also cool dramatically.
You can make a vortex tube pretty easy to see how the theory works. Take maybe a 6" piece of pipe, slide a washer into one end & solder it about halfway thru it (like a wall with a hole in it) and solder a cap on one end. Then you drill a small (like 1/8) hole just past the washer in the closed end, slanting the hole so the air you shoot in there will swirl along inside the pipe. Toward the capped end, drill a tiny (like 1/16") hole to attract a little of the air toward that end of the rube. Then you use your air compressor to run the thing, shooting a stream of air into the bigger hole. The air will begin to compress, finding the tiny hole and as it sets up a swirl in that direction, it can't escape fast enough, so it actually sets up another swirl INSIDE the bigger one but traveling toward the hole in the washer. It's hard to describe but kinda like starting a whirlpool of air. Sure enough, the closed end of the tube will get too hot to hold and the open end will start freezing. Fascinating projects, those vortek tubes. With enough compressor, you could cool a house yup! Or heat one. :)