Refrigeration Compressor is used to compress low pressure, low temperature vapour refrigerant to convert it into high pressure, high temperature vapour refrigerant. Compressor is located between evaporator and condenser. The vapour refrigerant from evaporator enters into compressor, gets compressed and is discharged to condenser.
Functions of Compressor in Refrigeration System:
1. Extracting or Removing the vapour refrigerant from the evaporator, so that, the desired pressure and temperature can be maintained.
2. Increasing the pressure of vapour refrigerant through the process of compression, and
3. Increasing the temperature of vapour refrigerant, so that, it would give up its heat to cooling medium in condenser.
In short: Compressor is used to take heat at low temperature with low pressure from the evaporator and pump it at high temperature with high pressure to the condenser. Therefore, it may be referred as heat pump.
Classification of Compressors
Positive displacement compressor
- Reciprocating compressor
- Open type compressor
- Hermetically sealed compressor
- Semi-hermetic compressor
- Rotary compressor
- Roller type rotary compressor
- Vane type compressor
- Screw compressor
Non-positive displacement compressor
- Centrifugal compressor
Types of Compressors
Positive displacement type compressor
Positive displacement compressors are further classified as reciprocating and rotary compressors. In these compressors, compression of vapour refrigerant is accomplished by means of a compressing member. In reciprocating compressor, the compressing member is the reciprocating piston, whereas, in the rotary compressor, the compressing member is in the form of a rotor, vane or lobe.
Non-positive displacement type compressor
Centrifugal compressor is a non-positive displacement type compressor. Here, no compressing member is present. The compression of vapour refrigerant is done or accomplished by the action of centrifugal force, which is developed, when the vapour refrigerant is rotated by a high speed impeller.