Refrigeration is a general term. It describes the process of removing heat from spaces, objects, or materials and maintaining them at a temperature below that of the surrounding atmosphere. To produce a refrigeration effect, the material to be cooled needs only to be exposed to a colder object or environment. The heat will flow in its NATURAL direction-that is, from the warmer material to the colder material. Refrigeration, then, generally means an artificial way of lowering the temperature. Mechanical refrigeration is a mechanical system or apparatus that transfers heat from one substance to another. You will find the concept of refrigeration easier to understand if you know the relationships among temperature, pressure, and volume, and how pressure affects liquids and gases.

HEAT

The purpose of refrigeration is to maintain spaces at low temperatures. Remember, you can-not cool anything by adding coolness to it; you have to REMOVE HEAT from it. Therefore, refrigeration cools by removing heat.

Heat and Temperature

It is important to know the difference between heat and temperature. HEAT is a form of energy. TEMPERATURE is a measure of the intensity of heat. The quantity or amount of heat energy in a substance is measured in BRITISH THERMAL UNITS (Btus). At atmospheric pressure, 1 Btu is the amount of heat required to raise the temperature of 1 pound of pure water 1F. In the opposite case, when 1 Btu is removed from 1 pound of water, the temperature of the water will drop 1F. Temperature, as you know, is measured in degrees. The degrees indicate the intensity of the heat in a given substance. Temperature does not indicate the number of Btus in the substance. For example, lets consider a spoonful of very hot water and a bucketful of warm water. Which has the higher temperature? Which has more heat? The heat in the spoonful of hot water is more intense; therefore, its temperature is higher. The bucketful of warm water has more Btus (more heat energy), but its heat is less intense.