A refrigerant circuit of a refrigeration apparatus performs a refrigeration cycle in which a high pressure is equal to or greater than the critical pressure of a refrigerant. The refrigeration apparatus performs at least a heat application operation in which an indoor heat exchanger of the refrigerant circuit functions as a radiator. A controller of the refrigeration apparatus controls the opening degree of the indoor expansion valve of the refrigerant circuit so that the temperature of the refrigerant at the outlet of the indoor heat exchanger reaches a predetermined reference temperature, in the heat application operation.

The invention provides a system for energy distribution that uses liquid carbon dioxide as a working fluid. Evaporation of the carbon dioxide provides cooling, and compression of the carbon dioxide gas back to the liquid state provides heat. The amount of heat transferred at both stages is sufficient to provide environmental heating and cooling. Waste thermal energy from a power plant, in the form of hot water, is fed into the system and used to drive the overall process. An underground thermal energy storage system is used to store energy flowing into the system that is in excess of the current demand.

A transport refrigeration system includes a compressor, a heat rejection heat exchanger, a flash tank, an expansion device and a heat absorption heat exchanger arranged in a serial refrigerant flow order to circulate a refrigerant; a controller configured to: determine a presence of at least one condition of the transport refrigeration system; and initiate a low refrigerant charge detection process in response to detecting the presence of the at least one condition of the transport refrigeration system.

A valve mechanism (14a, 14b, 63a, 63b, 90) includes: a valve body (80, 95); a first flow path (81) located opposite a distal end (80a, 95b) of the valve body (80, 95); a driver (85) configured to move the valve body (80, 95) to a first position where the distal end (80a, 95b) of the valve body (80, 95) closes the first flow path (81) and a second position where the distal end (80a, 95b) of the valve body (80) opens the first flow path (81); and a second flow path (82) configured to communicate with the first flow path (81) when the valve body (80) is at the second position. The high-pressure flow path (I1, I2, O2, O3, 48) causes the high-pressure refrigerant to always flow through the second flow path (82) and first flow path (81) of the valve mechanism (14a, 14b, 63a, 63b, 90) in this order.

An air source heat pump system includes at least one heat pump sub-system and at least one water tank. Each heat pump sub-system includes a refrigerant circulation path and a water supply circulation path. The refrigeration circulation path includes a compressor, a first heat exchanger, a first throttling device, and an evaporator that are sequentially connected to one another. The water supply circulation path includes a first supply pipe, a second supply pipe, a return pipe, and a waterway control valve. The first supply pipe and the second supply pipe are each communicated with an end of the first heat exchanger through the waterway control valve, and the return pipe is communicated with another end of the first heat exchanger. The return pipe is communicated with a water inlet of a corresponding water tank, and the second supply pipe is communicated with a water outlet of the corresponding water tank.

A primary refrigerant circuit allows circulation of a primary refrigerant and includes a primary compressor, a cascade heat exchanger, a primary heat exchanger, and a primary switching mechanism. A secondary refrigerant circuit allows circulation of a secondary refrigerant and includes a secondary compressor, the cascade heat exchanger, a utilization heat exchanger, and a secondary switching mechanism. The secondary refrigerant circuit includes a bypass flow path connecting a portion between the utilization heat exchanger and the cascade heat exchanger and a suction flow path of the secondary compressor, and a bypass expansion valve provided on the bypass flow path. Executed is defrosting operation of circulating the primary refrigerant in the order of the primary compressor, the primary heat exchanger, and the cascade heat exchanger, and circulating the second refrigerant in the order of the secondary compressor, the cascade heat exchanger, and the bypass flow path.

A cooling system implements various processes to improve efficiency in high ambient temperatures. First, the system can flood one or more low side heat exchangers in the system. Second, the system can direct a portion of vapor refrigerant from a low side heat exchanger to a flash tank rather than to a compressor. Third, the system can transfer heat from refrigerant at a compressor suction to refrigerant at the discharge of a high side heat exchanger.

Systems and methods for controlling pressure in a CO.sub.2 refrigeration system are provided. The pressure control system includes a pressure sensor, a gas bypass valve, a parallel compressor, and a controller. The pressure sensor is configured to measure a pressure within a receiving tank of the CO.sub.2 refrigeration system. The gas bypass valve is fluidly connected with an outlet of the receiving tank and arranged in series with a compressor of the CO.sub.2 refrigeration system. The parallel compressor is fluidly connected with the outlet of the receiving tank and arranged in parallel with both the gas bypass valve and the compressor of the CO.sub.2 refrigeration system. The controller is configured to receive a pressure measurement from the pressure sensor and operate both the gas bypass valve and the parallel compressor, in response to the pressure measurement, to control the pressure within the receiving tank.

The present disclosure is directed to an aircraft power generation system including a reverse Brayton cycle system, a gas turbine engine, and a gearbox. The gas turbine engine includes a compressor section, a turbine section, and an engine shaft. The compressor section is arranged in serial flow arrangement with the turbine section. The engine shaft is rotatable with at least a portion of the compressor section and with at least a portion of the turbine section. The reverse Brayton cycle system includes a compressor, a driveshaft, a turbine, and a first heat exchanger. The driveshaft is rotatable with the compressor or the turbine, and the compressor, the first heat exchanger, and the turbine are in serial flow arrangement. The gearbox is configured to receive mechanical energy from the engine shaft and transmit mechanical energy to the reverse Brayton cycle system through the driveshaft.

An air-conditioner includes: a return-air inlet and a supply-air outlet each communicating with a predetermined space; a first main air channel configured to allow air to flow therein towards the supply-air outlet; a first heat exchanger disposed in the first main air channel and that causes heat-exchange between refrigerant flowing therein and air passing therethrough; an exhaust-air outlet communicating with an outside of the predetermined space; a second main air channel configured to allow air to flow therein towards the exhaust-air outlet; a second heat exchanger disposed in the second main air channel and that causes heat-exchange between refrigerant flowing therein and air passing therethrough; and an exhaust ventilation channel configured to allow air to flow therein from the return-air inlet towards the exhaust-air outlet.