Refrigeration & Equipment Engineering

Unit 3 - Parts of refrigeration systems

3.1.2.1.Reciprocating compressors
Reciprocating compressors are those in which piston moves in a cylinder in reciprocating motion with the help of connecting rod, crank shaft etc. to compress the refrigerant.

The functions of reciprocating compressor in vapor compression refrigeration system are as follows.

• It sucks and discharge the refrigerant
• It compresses the low temperature and low pressures vapor into high temperature and high pressure vapor.
• It creates the flow of refrigerant.

Reciprocating compressors are used for refrigerants which have comparatively low volume per kg and a large differential pressure, such as R717, R12,R22 and R-40. The reciprocating compressors are available in sizes from 1/12kw which are used in small domestic refrigerators and up to about 150kw for large capacity installations.
The two types of reciprocating compressor in general use are single acting vertical compressors and double acting compressors. The single acting compressors usually have their cylinders arranged vertically, radially or in a V or w form. The double acting compressors have their cylinders arranged horizontally.