Heat-pump with sub-cooling heat exchanger

Claim 1

A reversible compression type refrigeration system having a first (heating) mode and a second (cooling) mode, a first fluid stream having thermal communication with a heat source/sink, and a second fluid stream, said system comprising first main (service) heat exchanger means having a fluid stream inlet and fluid stream outlet, said first main heat exchanger providing means for evaporating refrigerant and for absorbing heat from the first fluid stream during the first (heating) mode and for condensing refrigerant and for rejecting heat to the first fluid stream during the second (cooling) mode, second main (process) heat exchanger means for evaporating refrigerant and for absorbing heat from the second fluid stream during the second (cooling) mode and for condensing refrigerant and for rejecting heat to the second fluid stream during the first (heating) mode; a compressor having a suction connection and a discharge connection; valve means for connecting the compressor suction connection to the second main (process) heat exchanger and the compressor discharge connection to the first main (service) heat exchanger during the cooling mode and for connecting the compressor discharge connection to the second main (process) heat exchanger and the compressor suction connection to the first main (service) heat exchanger during the heating mode; receiver means for receiving liquid refrigerant from the first main (service) heat exchanger during the cooling mode and from the second main (process) heat exchanger during the heating mode; an expansion device; liquid refrigerant conduit means for conveying liquid refrigerant from the receiver means to the expansion device, and a first sub-cooling heat exchanger positioned in the liquid refrigerant conduit means and subject to the fluid stream entering the first main heat exchanger.