Refrigeration is the process of removing heat from where it is not wanted. Heat is removed from food to preserve its quality and flavor. It is removed from room air to establish human comfort. There are innumerable applications in industry in which heat is removed from a certain place or material to accomplish a desired effect.

During refrigeration, unwanted heat is transferred mechanically to an area where it is not objectionable. A practical example of this is the window air conditioner that cools air in a room and exhausts hot air to the outdoors. The liquid called the refrigerant is fundamental to the heat transfer accomplished by a refrigeration machine.

Practically speaking, a commercial refrigerant is any liquid that will evaporate and boil at relatively low temperatures. During evaporation or boiling, the refrigerant absorbs the heat. The cooling effect felt when alcohol is poured over the back of your hand illustrates this principle.

In operation, a refrigeration unit allows the refrigerant to boil in tubes that are in contact, directly or indirectly, with the medium to be cooled. The controls and engineering design determine the temperatures reached by a specific machine.

So what exactly is refrigeration?

It is the process of cooling of bodies or fluids to temperatures lower than those available in the surroundings, at a particular place and time.

But, do not confuse it with the process of cooling! Cooling is a spontaneous process, and the final temperature need not be lower than the surroundings. eg. Cooling a hot cup of coffee.

How is air conditioning different from refrigeration?

Air conditioning refers to the treatment of air so as to simultaneously control its temperature, humid moisture content, quality and circulation. Refrigeration only deals with maintaining a lower temperature.