Cooling Techniques
Phase changes and Heat
Refrigeration is defined as the process of cooling an object by removing some of its heat and transporting it away from the object. In a domestic refrigerator, this is achieved by the use of a liquid with a low boiling point to transport the heat away from the inside compartment to the outside of the refrigerator.
When liquids evaporate, they are undergoing a phase change from liquid to gas. In order for the molecules in the liquid to escape into the gaseous state, they require energy to overcome the strong forces present. This energy is known as the latent heat of evaporation. As they leave the liquid, the molecules draw energy from their surroundings, cooling the liquid as they carry the energy away.
Upon condensing, the process is reversed. The gas undergoes a phase change from gas to liquid and the energy is released.
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