See Also: Air Conditioner, Heat Pump
Process for drawing Heat from substances to lower their Temperature, often for purposes of preservation. Mechanical refrigeration systems (first
patented in 1834) are based on the principle that absorption of heat by a fluid
(refrigerant) as it changes from a liquid to a Gas (see States Of Matter) lowers the temperature of the objects around it. In the compression system,
employed in electric home refrigerators, a Compressor, controlled by a thermostat, exerts Pressure on a refrigerant gas (usually Freon or Ammonia), forcing it to pass through a condenser, where it loses heat and liquefies.
When the liquid is circulated through refrigeration coils, it vaporizes,
drawing heat from the air surrounding the coils. The refrigerant gas then returns to
the compressor, and the cycle is repeated. In the absorption system, widely
used in commercial installations, ammonia is used to cool brine, which is then
piped (see Specifications - Piping) into the refrigerated space.