Patent ID: 8322150

Claim:
A refrigeration system comprising: an evaporator, a two-stage compressor for compressing a refrigerant, the two-stage compressor having a suction port, an interstage port, and a discharge port; a first single-stage compressor for compressing the refrigerant, the first single-stage compressor having a suction port and a discharge port, wherein the first single-stage compressor is configured to discharge into the interstage port of the two-stage compressor; a heat rejecting heat exchanger for cooling the refrigerant; a first economizer circuit configured to inject refrigerant into the interstage port of the two-stage compressor, the first economizer circuit having an economizer heat exchanger and an expansion valve; and a second economizer circuit configured to inject refrigerant into the suction port of the first single-stage compressor, the second economizer circuit having an economizer heat exchanger and an expansion valve.