Patent ID: 7204099

Claim:
A refrigerant system comprising: at least one compressor delivering refrigerant downstream to a condenser, an economizer heat exchanger downstream of said condenser, a main flow line passing from said condenser through said economizer heat exchanger, a tap line being tapped off said main flow line and passing a tapped flow of refrigerant through said economizer heat exchanger to cool refrigerant in said main flow line, said tapped flow being returned into at least one intermediate compression pocket into said at least one compressor; said refrigerant in said main flow line passing through a main expansion device and an evaporator and then back to said at least one compressor; and said tapped flow being returned to said at least one compressor through an economizer injection line, and a liquid refrigerant being injected into said at least one compressor through a liquid injection line, with said liquid injection line and said economizer injection line being separate fluid lines.