The function of refrigerators is based off of two simple concepts:
1. Gases cool when they expand
2. The second law of thermodynamics (heat flows from hot to cold bodies)
Here is a diagram to help explain how it works.
Most modern refrigerators today use a gas called HFC-134a, or tetrafluoroethane, which is stored in the tubes. Here is the cycle of refrigeration.
1. HFC-134a is compressed by the compressor, it heats up. (Pv=nRT, as P increases, T increase.)
2. The gas passes through the tubes outside the refrigerator (red), where it cools and becomes a liquid. The heat is released outside of the refrigerator.
3. The liquid then must pass through the expansion valve, a tiny hole leading to the freezer compartment.
4. Since the pressure is higher in the red tubes than in the blue tubes, the liquid HFC turns into a gas as it moves in the blue tubes.
5. The gas HFC adsorbs the heat in the freezer, and thus the freezer becomes cold.
6. HFC then passes back through the compressor, where a new cycle begins.
Thanks for reading!