Patent ID: 8418482

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