Importance

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Abstract

An environmental control system disclosed includes a refrigeration loop including a two stage centrifugal compressor having an inlet and an outlet, a condenser having an inlet connected with the compressor outlet and an outlet, and an evaporator having an inlet connected with said condenser outlet and an outlet connected with the compressor inlet, a motor for rotating the compressor, control means responsive to evaporator load for establishing the rate of rotating said compressor, a controllable expansion valve in communication with the refrigeration loop, an expansion valve control to control the setting of the expansion valve, a bypass valve in communication with the refrigeration loop and also in communication with one stage of the compressor, wherein the bypass valve is selectively openable to allow circulated refrigerant to be variably communicated to the stage in communication therewith, and wherein the setting of the expansion valve is also a function of bypass valve operation.

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First Claim