A mixture of hydrocarbons in vapour phase is passed through a feed scrubber. Feed scrubber vapour discharged from the feed scrubber is passed to a compression suction scrubber, and a vaporous compressor feed stream from the compression suction scrubber is compressed in a compressor train. A compressed vaporous discharge stream from the train of compressors is de-superheated, and at least a portion of the de-superheated stream is passed to a condenser, wherein this portion of the de-superheated stream is at least partly condensed to form a pressurized and at least partially condensed mixture of hydrocarbons. A recycle portion is split off from the de-superheated hydrocarbon stream, and a recycle flow is established to the compressor train of via a surge recycle separator drum and the compression suction scrubber. Liquid constituents removed and drained from the recycle portion in the surge recycle separator drum are fed to the feed scrubber.

A compressed vaporous discharge stream is de-superheated in a de-superheater system. The de-superheater system comprises a de-superheater heat exchanger configured to bring at least a portion of the compressed vaporous discharge stream in indirect heat exchanging contact with an ambient stream. A de-superheater bypass line comprising an temperature-controlled valve is configured to selectively bypass the de-superheater heat exchanger. A combiner is configured downstream of the de-superheater heat exchanger for rejoining the bypass portion with the portion of the compressed vaporous discharge stream that has passed through the de-superheater heat exchanger. A mixer is configured downstream of said combiner, to receive and mix the rejoined stream, and discharge the rejoined stream into a de-superheater discharge conduit as a de-superheated stream.

An HVAC system is disclosed, comprising: (a) a compressor, (b) a source heat exchanger for exchanging heat with a source fluid, (c) a first load heat exchanger operable for heating/cooling air in a space, (d) a second load heat exchanger for heating water, (e) first and second reversing valves, (f) first and second 3-way valves, (f) a bi-directional electronic expansion valve, (g) a first bi-directional valve, and (h) a second bi-directional valve to modulate exchange of heat in the first load heat exchanger when operating as an evaporator and to control flashing of the refrigerant entering the source heat exchanger when operating as an evaporator, (h) a source pump for circulating the source fluid through the first load heat exchanger, (i) a water pump for circulating water through the second load heat exchanger, and (j) a controller to control operation of the foregoing.

An apparatus includes a high side heat exchanger, a flash tank, a load, a compressor, and a heat exchanger. The high side heat exchanger removes heat from a refrigerant. The flash tank stores the refrigerant from the high side heat exchanger and to discharge a flash gas. The load uses the refrigerant from the cool a space proximate the load. The compressor compresses the refrigerant from the load. The heat exchanger transfers heat from the refrigerant from the compressor to the flash gas before the refrigerant from the compressor reaches the high side heat exchanger. The heat exchanger directs the flash gas to the compressor after heat from the refrigerant from the compressor is transferred to the flash gas and directs the refrigerant from the compressor to the high side heat exchanger after heat from the refrigerant from the compressor is transferred to the flash gas.

A transcritical refrigeration system includes a gas cooler/condenser; a receiver configured to collect refrigerant produced by the refrigeration system; a gas bypass valve fluidly coupled to the outlet of the receiver and operable to control a pressure of the refrigerant in the receiver; and a medium temperature subsystem. The medium temperature subsystem includes one or more expansion valves; one or more medium temperature evaporators; and a suction group including one or more transcritical compressors operable to compress gas refrigerant and discharge the compressed gas refrigerant into a discharge line. The system includes a superheat control system that includes a heat exchanger system including a first side configured to carry gas refrigerant passing between the gas cooler/condenser and an inlet of the receiver, and a second side in heat transfer communication with the first side.