Patent ID: 8225624

Claim:
A refrigeration system comprising: a compressor that includes a compressor main unit constituting a positive-displacement fluid machine with a plurality of compression chambers to cyclically change the capacities of the compression chambers and a drive shaft for driving the compressor main unit; and a refrigerant circuit connected with the compressor and operable in a refrigeration cycle, wherein the compressor main unit is configured so that first and second said compression chambers differ in the phase of capacity changing cycle from each other by 180° and third and fourth said compression chambers differ in the phase of capacity changing cycle from each other by 180°, the compressor is selectively operable in a parallel compression mode in which refrigerant is compressed in a single stage in each of the first to fourth compression chambers and a cylinder nonoperating mode in which refrigerant is compressed in a single stage in each of the third and fourth compression chambers while compression of refrigerant in the first and second compression chambers is halted, and the first compression chamber is disposed below the second compression chamber in a direction along a rotating axis of the drive shaft and the third compression chamber is disposed below the fourth compression chamber in the direction along the rotating axis of the drive shaft.