A transport refrigeration system (100) including a container (10) having an outer wall defining at least one compartment. Also included is a first refrigerant system section (202) disposed at an exterior location of the outer wall of the container, the first refrigerant system section having a first refrigerant routed therethrough for cooling of the first refrigerant. Further included is a second refrigerant system (204) section disposed at least partially within an interior location of the outer wall of the container, the second refrigerant system section having a second refrigerant that is different from the first refrigerant routed therethrough for cooling of the second refrigerant. Yet further included is a heat exchanger (240) in fluid communication with the first refrigerant system section to receive the first refrigerant, the heat exchanger in fluid communication with the second refrigerant system section to receive the second refrigerant, the first refrigerant cooling the second refrigerant within the heat exchanger.

A refrigerant control system for controlling a first refrigerant flowing through a first circulation passage connected to a compression unit, including a storing unit which stores a first refrigerant, a first sub-pipe which is connected to an outlet side pipe, a second sub-pipe which is connected to an inlet side pipe, a first opening/closing valve which is provided in the first sub-pipe and is capable of switching whether to flow the first refrigerant in the outlet side pipe to the storing unit, a second opening/closing valve which is provided in the second sub-pipe and is capable of switching whether to flow the first refrigerant in the storing unit to the inlet side pipe, and an opening/closing control unit which controls an opening/closing state of the first opening/closing valve and the second opening/closing valve on the basis of a setting temperature of a second refrigerant set according to a predetermined method.

A vapor compression refrigeration system has a main refrigerant circuit having a primary compressor group, a gas cooler or condenser, an expansion device, a liquid receiver, and at least one evaporator. An emergency circulation duct fluidically connects the liquid receiver to the main circuit to allow a flow of refrigerant from the liquid receiver to the gas cooler. An emergency compressor group in the emergency circulation duct is activatable when pressure inside the liquid receiver or in the duct upstream of the emergency compressor group meets or exceeds a predefined emergency pressure threshold. An uninterruptible power supply powers the emergency compressor group and expansion device during a shutdown of the refrigeration system. When pressure inside the liquid receiver or in the duct upstream of the emergency compressor group equals or exceeds the predefined emergency pressure threshold, an emergency circulation of refrigerant fluid is activated through the emergency circulation duct.

A method for operating a cooling device, a cooling device and a test chamber having a cooling device, a temperature of at least −80° C. or lower being established at the heat exchanger by means of the cooling device having a cooling circuit comprising a refrigerant, a heat exchanger, an internal heat exchanger, a compressor, a condenser and a controllable expansion element of the cooling device, the refrigerant undergoing a phase transition in the heat exchanger, the refrigerant of a high-pressure side of the cooling circuit being cooled by means of the internal heat exchanger, the cooling of the refrigerant of the high-pressure side by means of the internal heat exchanger being used to reduce an evaporation temperature at the expansion element, a zeotropic refrigerant being used as refrigerant, the expansion element being controlled by means of a control device of the cooling device in such a manner that the refrigerant partially freezes during an expansion at the expansion element.

The present disclosure relates to a heating ventilation and air conditioning (HVAC) system. The system includes a primary heat transfer loop configured to be disposed at least partially outside of a building, and the primary heat transfer loop includes a heat exchanger, a compressor configured to compress a refrigerant, where the refrigerant is reactive, a condenser configured to receive and condense the refrigerant, and an expansion device configured to reduce a temperature of the refrigerant. The system further includes a secondary heat transfer loop configured to circulate a two-phase fluid at least partially inside the building, wherein the two-phase fluid is less reactive than the refrigerant. The secondary heat transfer loop includes the heat exchanger, where the heat exchanger is configured to transfer energy from the two-phase fluid circulating in the secondary heat transfer loop to the refrigerant, and an evaporator configured to evaporate the two-phase fluid by exchanging energy with an air supply stream flowing across the evaporator.

To provide a defrost system capable of preferable defrosting and prevention of generation of icicles on a casing without installing a brine circuit. A defrost system includes a thermosiphon defrost circuit that is provided by being branched from a circulation line, in which, at the time of defrosting, a CO.sub.2 refrigerant staying inside a fin-tube heat exchanger repeats a two-phase change of a gaseous form and reliquefaction, and which forms a CO.sub.2 circulation path together with the fin-tube heat exchanger; electromagnetic opening/closing valves and that are closed at the time of defrosting and set the CO.sub.2 circulation path to a closed circuit; and a first electric heater arranged above the thermosiphon defrost circuit so as to be adjacent to the thermosiphon defrost circuit, and naturally circulates the CO.sub.2 refrigerant in the closed circuit at the time of defrosting.

A CO.sub.2 refrigeration system, includes a receiving tank, a condenser, a low temperature system, and a medium temperature system. The low temperature system is fluidly coupled to the receiving tank and the condenser. The low temperature system includes a plurality of low temperature evaporators, a plurality of low temperature expansion valves, a plurality of low temperature compressors, and a plurality of flexible low temperature conduits fluidly coupling the low temperature compressors to a low temperature discharge header and a low temperature suction header. The medium temperature system is fluidly coupled to the receiving tank and the low temperature system. The medium temperature system includes a plurality of medium temperature evaporators, a plurality of medium temperature expansion valves, a plurality of medium temperature compressors, and a plurality of flexible medium temperature conduits fluidly coupling the medium temperature compressors to a medium temperature discharge header and a medium temperature suction header.

A compressor may include a shell assembly, a compression mechanism and a conduit. The shell assembly may include a fitting through which fluid is received from outside of the compressor. The compression mechanism may be disposed within a chamber defined by the shell assembly. The conduit may extend through the chamber between the fitting and a suction inlet of the compression mechanism and transmit at least a portion of the fluid from the fitting to the suction inlet. The conduit may include an inlet that may be spaced apart from the fitting and an outlet that may engage the compression mechanism.

A closed cooling system for cooling a fluid of an open fluid system including a first heat exchanger and a compressor facilitating circulation of a refrigerant in the closed cooling system, where the refrigerant facilitates providing a solid state cooling bank which is thermally coupled to the open fluid system thereby cooling fluid conducted through the open fluid system.

A control method of a transcritical carbon dioxide composite heat pump system is disclosed, wherein the transcritical carbon dioxide composite heat pump system includes: a CO.sub.2 main circuit compressor, an air-cooling-air-cooling recombiner, a supercooling-evaporation recombiner, an evaporator and a CO.sub.2 auxiliary compressor; wherein the air-cooling-air-cooling recombiner comprises a CO.sub.2 main circuit, a CO.sub.2 auxiliary circuit and a water circuit; the supercooling-evaporation recombiner comprises a CO.sub.2 main circuit supercooling section and a CO.sub.2 auxiliary circuit evaporation section. The present invention includes two working modes according to the return water temperature, so that the unit has a wider application range and meets daily needs. There is only one heat exchanger for refrigerant and water. Compared with the three water and refrigerant heat exchangers in the conventional transcritical CO.sub.2 composite heat pump, the circulating water circuit is a single circuit with one inlet and one outlet.