Refrigeration Cycle:

The term 'refrigeration' can be defined as the procedure of eliminating heat from a substance under controlled conditions. It also includes the procedure of reducing & maintaining the temperature of particular body below the normal temperature of its surroundings. In other terms, the refrigeration refers a continued extraction of heat from a body that temperature is already below temperature of its atmosphere. In a refrigerator, virtually heat is pumped up from a lower temperature to a higher temperature. By according Second Law of Thermodynamics, this procedure can just be done with the aid of some external work. Thus it is clear that regularly supply of power is needed to drive a refrigerator. Theoretically speaking, a refrigerator is a reversed heat engine or a heat pump that pumps heat from a cold body & delivers it to a hot one. The substance that works in a pump to extract heat from a cold body & to deliver this to a hot one is known as refrigerant.

Objectives

After studying this unit, you should be able to

• know about refrigeration cycle,
• understand what is the vapour compression cycle,
• explained the vapour compression refrigeration cycle, and
• Solve out the problem on refrigeration system.

Refrigeration cycle is the origin of all refrigeration systems. Therefore refrigeration cycle must be known to understand the refrigeration system. Some fundamental refrigeration cycles are described here through different diagrams.