system
Given the following post, respond as if you're commenting on Reddit:
human
How exactly do refrigerators cool things down? And what qualifies certain chemicals as refrigerants?
gpt
When a gas expands it takes in energy from its surroundings...making things around it cooler. When you compress a gas the gas gives off energy. Refrigeration works by compressing a gas and expelling the heat with a fan and/or radiator then moving the compressed gas to the area to be cooled and allowed to expand, drawing in heat. The expanded gas is moved back to the compressor and they cycle continues.

Any gas can be a refrigerant really, but a good refrigerant has a high heat capacity so each unit of gas can move more energy.