In order to provide climate control system for heating or cooling a space, in particular a vehicle interior, having a compressor for conveying a refrigerant, which can efficiently use the refrigerant CO.sub.2 for heat pump applications as well, it is proposed to arrange a high-pressure chiller for cooling the refrigerant downstream of the compressor and a low-pressure chiller for heating the refrigerant upstream of the compressor, wherein a refrigerant exiting from the high-pressure chiller can be supplied to a motive mass inlet of a first ejector and a refrigerant exiting from the low-pressure chiller can be supplied to a suction mass inlet of the first ejector, and wherein an outlet of the first ejector is connected directly or indirectly to a liquid separator.

A CO.sub.2 cooling system includes a compression stage in which CO.sub.2 refrigerant is compressed; a cooling stage in which the CO.sub.2 refrigerant releases heat; a CO.sub.2 liquid receiver in which the CO.sub.2 refrigerant is accumulated in liquid and gaseous states; an evaporation stage in which the CO.sub.2 refrigerant, having released heat in the cooling stage, absorbs heat. The evaporation stage has first and second evaporation sectors; a first metering device for feeding CO.sub.2 refrigerant into the first evaporation sector at a first pressure; and a second metering device for feeding CO.sub.2 refrigerant into the second evaporation sector at a second pressure. The first metering device and the second metering device are operated independently from one another. A plurality of CO.sub.2 transfer lines connects the compression stage, the cooling stage, the CO.sub.2 liquid receiver and the evaporation stage. The CO.sub.2 refrigerant is circulable in a closed-loop circuit.

Thermoelectric enhanced hybrid heat pump systems are provided herein. A compressor increases the pressure of refrigerant within tubing. A first heat exchanger is downstream of the compressor and changes enthalpy of first fluid flow through heat exchange with refrigerant. A second heat exchanger changes enthalpy of second fluid flow through heat exchange with refrigerant. A thermoelectric device is downstream of the first heat exchanger and reduces refrigerant temperature. Expansion valves are downstream of the thermoelectric device and first heat exchanger, respectively located on first and second sides of the thermoelectric device, and expand refrigerant and reduce refrigerant pressure while conserving refrigerant enthalpy. At least one valve reverses refrigerant flow within the tubing without changing compressor operation. A control system controls the thermoelectric device and at least one valve to switch the heat pump system from heating mode to cooling mode and from cooling mode to heating mode.

A refrigeration system operable in cooling mode and defrosting mode is provided. The refrigeration system includes a defrost line connecting a first reservoir to an evaporation stage for conveying at least part of the flash gas from the first reservoir to the evaporation stage when the refrigeration system is operating in defrosting mode. The flash gas thereby releases heat in the evaporation stage for defrosting the evaporation stage. The refrigeration system can also include a discharge line connecting the evaporation stage to a second reservoir.

A cooling system includes a compressor configured to pressurize carbon dioxide to form pressurized carbon dioxide, a mixer configured to generate mixed refrigerant in which the pressurized carbon dioxide and solvent in a liquid state, a depressurization apparatus provided downstream from the mixer and configured to depressurize the mixed refrigerant, a separator configured to separate carbon dioxide in a gas state from the mixed refrigerant, a heat exchanger configured to exchange heat between the mixed refrigerant cooled through depressurization and a fluid to be cooled, and a second heat exchanger configured to cool the carbon dioxide or the mixed refrigerant using vaporized carbon dioxide or the mixed refrigerant.

A system and method for increasing the efficiency of natural gas liquefaction processes by using a hybrid cooling system and method. More specifically, a system and method for converting a transcritical precooling refrigeration process to a subcritical process. In one embodiment, the refrigerant is cooled to sub-critical temperature using an economizer. In another embodiment, the refrigerant is cooled to a sub-critical temperature using an auxiliary heat exchanger. Optionally, the economizer or auxiliary heat exchanger can be bypassed when ambient temperatures are sufficiently low to cool the refrigerant to a sub-critical temperature. In another embodiment, the refrigerant is isentropically expanded.

Systems and methods for implementing ejector refrigeration cycles with cascaded evaporation stages that utilize a pump to optimize operation of the ejector and eliminate the need for a compressor between the evaporation stages.

A fluid handling system includes a pressure exchanger (PX) configured to receive a first fluid at a first pressure and a second fluid at a second pressure and exchange pressure between the first fluid and the second fluid. The system further includes a condenser configured to provide corresponding thermal energy from the first fluid to a corresponding environment. The system further includes a receiver to receive the first fluid output by the PX. The receiver forms a chamber to separate the first fluid into a first gas and a first liquid. The system further includes a heat exchanger configured to receive the second fluid from the second outlet of the PX and provide the second fluid to the second inlet of the PX.

A method of operating a refrigeration and heating system (2a, 2b) comprises: circulating a refrigerant through a refrigeration circuit (4) which comprises in the direction of flow of the circulating refrigerant: at least one compressor (6a, 6b, 6c); a refrigeration circuit side (8a) of a coupling heat exchanger (8); at least one gas cooler (10); at least one expansion device (12, 14); and at least one evaporator (16); circulating a heating fluid through a heating circuit (20) which comprises a heating circuit side (8b) of the coupling heat exchanger (8) and at least one heat consumer (22); wherein the coupling heat exchanger (8) is configured for transferring heat from the circulating refrigerant to the circulating heating fluid. The method further includes increasing the temperature of the refrigerant entering the at least one gas cooler (10) in order to meet increased heating demands by allowing at least a portion of the heating fluid to flow directly from an outlet to an inlet of the heating circuit side (8b) of the coupling heat exchanger (8) bypassing the at least one heat consumer (22) or by allowing at least a portion of the refrigerant circulating through the refrigeration circuit (4) to bypass the coupling heat exchanger (8).

A gas turbine engine may include a deep heat recovery system, such as a deep heat recovery super critical carbon dioxide (sCO2) system. The deep heat recovery system may include two-stage cooling of the working fluid (such as carbon dioxide—CO2) where at least one of cooling stages is recuperative by transferring heat from the working fluid to a flow of compressed air being supplied to a combustor included in the gas turbine engine. The deep heat recovery system may operate in a supercritical cycle, or in a transcritical cycle depending on the temperature to which the working fluid is cooled during a second stage of the two-stage cooling. The second stage of the two-stage cooling includes working fluid-to-air heat rejection where the air is ambient air.