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Have you ever poured or spilled a liquid on your skin and been chilled by the liquid as it evaporated? Did you notice that some liquids cooled much faster than others because they evaporated faster? The reason for this cooling effect is that liquids evaporating, turning from liquids into gases, take heat from their surroundings to make this transition. Well if you understand that you have about one half of the way a refrigerator works.

The other half of the way a refrigerator works involves the fact that a gas can be compressed until it turns into a liquid. When a gas is compressed into changing state to a liquid, it gives off heat to its surroundings. The refrigerator is both a gas compressor and a liquid evaporator.

The refrigerator is a sealed system made up of tubes to carry a substance that is called a coolant, which is a gas at room temperature, to the compressor that has a motor which compresses or squeezes the gas into a liquid. The liquid is pumped into a closed box, the inside of the refrigerator, where it picks up heat from the surrounding air and is evaporated, turning into a gas again and starting the cycle all over again.

It is the heat that is carried out of the small container (the inside of the refrigerator) by the coolant that acts like a dump truck. The coolant as a liquid picks up heat from the small space of the inside of the refrigerator and "dumps" it outside into the larger space of the room when it is turned to a liquid.

This cycle is repeated over and over as the refrigerator's motor acts as a pump to move the gas coolant and a compressor to convert the gas to liquid. Heat is pumped out of the inside of the refrigerator by the liquid it picks up and changing state to a gas. The coolant dumps the heat during compression and change of state to a liquid by giving up heat to the room. If you think of the coolant as a dump truck picking up and dumping heat, you've got the idea.

Refrigeration and air conditioning work on the same principle. That principle is the use of the change of state of a gas to a liquid through compression to form a cold liquid, which is then pumped to a site to remove heat from a contained area. In a refrigerator that area is a small air tight box. The liquid coolant, in most cases freon or a similar gas, acts like a dump truck picking up heat from its surrounding. It continues to collect this heat until it (the liquid coolant)evaporates. This now turns the coolant to a gas which carries away the heat to the outside of the refrigerator to the coils where the heat is "dumped" into the outside room. The coolant now a gas is then compressed and the cycle begins again.

Gas-to-liquid the coolant dumps heat, liquid-to-Gas the coolant picks up heat. The cycle continues with the use of evaporation and condensation as the method of cooling. The technical name for this is the Carnot cycle. Refrigeration through the use of mechanical means is a simple process but one that is important to modern life in ways that we don't even think about. But what would life be like if we were not able to keep food in our refrigerator?