Monday, February 11, 2013

How refrigerators work

I've tried explaining to myself and others how refrigerators work before. I kinda understood. I get the bit about using freon to absorb the heat on the inside and shed the heat on the outside. And I knew there was some compression involved. I wasn't sure how that worked though.

Also known - asteroids heat up on atmospheric entry due to atmospheric compression.

I finally started making some connections after exchanging some e-mails with the XKCD guy. He didn't really explain it, but in trying to phrase my follow up question it started to click. Here's what I've got.

Hot air (or other objects) expands. Cold air (see previous parenthesis) contracts. Well established back in science class. Heat goes in and it gets bigger. Cold goes in and it gets smaller. But cold doesn't really go in. We just make it easier for heat to come out.

So, take a quantity of air and compress it. Being forced to contract, the air gets colder. It's heat must be shed so the container gets warm. In the case of an asteroid, the air can't move out of the way fast enough, it gets compressed, and sheds it's heat into the asteroid.

Take a can of compressed air and fire it at something. That something tends to get cold. As the air  comes out it expands it wants it's heat back. It's heat was stolen when it was put into that can. You thought it forgot about that? All those years, locked away in a cell, it's been planning... plotting it's revenge. It wants it's heat back! And it doesn't want to hear about how you used it to start that diner outside of Boston!

I may be drifting from my point a bit.

The air pulls the heat from it's surroundings. So the hand, the electronics, the guy you're having an air can war with, get colder and can get condensation or even frost.

So what does this have to do with the refrigerator? Well, whatever is being pumped through the tubes decompresses in the tubes inside the fridge. It needs heat for this so that heat is pulled out of the fridge and the food. It then gets pumped to tubes outside the fridge where pumps smoosh it all back into a tight space so it sheds the heat into the kitchen.

Air or water or something else could be used, but someone did research that found that freon was pretty good at being expanded and contracted a lot and pushing heat energy around. It's also really good at destroying ozone.

This seems sound to me, but I admit I have trouble figuring out good ideas from bad sometimes.

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