REFRIGERATION System & Refrigeration cycle

Generally, refrigeration is used for temperature requirements from 80 – 85 degree F to as near

absolute zero as the process demands. The petrochemical and chemical range does not go

much below -200 degree F. Refrigeration process consists of five component equipment, they

are

1. Compressor.

2. Evaporator.

3. Condenser.

4. Expansion Valve.

5. And Refrigerant.

A general equipment arrangement of Refrigeration cycle shows in Figure 1.

                         Fig 1

Refrigerant vapor enters the compressor suction and the compressor raises the refrigant

pressure so the saturation temperature is above the temperature of the available cooling

medium. This difference allows transfer of heat from the vapor to the cooling medium so

that the vapor can condense to a liquid. The condensed liquid then flows through the

expansion device such as expansion valve and flashes into a vapor, cooling the remaining

liquid refrigerant below the temperature of the product to be cooled.

This difference in temperature allows heat to be transferred from the product to the

refrigerant, causing the refrigerant to evaporate. The vapor formed must be removed by

the compressor at a rate sufficient to maintain the low pressure in the evaporator and keep

the refrigerant flowing. The resulting continuous flow process is referred to as the

refrigeration cycle, shown schematically in Figure 2. This cycle is also called the reverse

ranking cycle and is governed by the principles of thermodyanmics.

                           Fig 2.