A test chamber and a method for conditioning air in a temperature-insulated test space of a test chamber, which is sealable against an environment and serves for receiving test material, a temperature ranging from −20° C. to +180° C. being produced within the test space by means of a cooling device of a temperature control device of the test chamber, using a cooling circuit with carbon dioxide (CO.sub.2) as a cooling agent, using a heat exchanger in the test space, using a low-pressure compressor and using a high-pressure compressor downstream of the low-pressure compressor, using a gas cooler, using a storage means for the cooling agent and using an expansion valve, the temperature in the test space being controlled and/or regulated by means of a control device of the test chamber. A gaseous and/or liquid cooling agent is dosed in the storage means by means of a high-pressure valve of the cooling circuit downstream of the gas cooler, the storage means being connected to a medium-pressure side of the cooling circuit upstream of the high-pressure compressor and downstream of the low-pressure compressor via a medium-pressure bypass of the cooling circuit, the gaseous cooling agent being dosed in the medium-pressure side from the storage means by means of a medium-pressure valve when the low-pressure compressor is switched off.

A single-stage carbon dioxide multi-split cooling and heating multifunctional central air conditioner, comprising a single-stage carbon dioxide circulation system using carbon dioxide as a circulation working medium; the single-stage carbon dioxide circulation system comprises an outdoor unit and a plurality of end heat exchangers provided in parallel; and the carbon dioxide medium performs cooling and/or heating in a circulating manner in a carbon dioxide compressor, an outdoor heat exchanger, a liquid storage tank and the end heat exchangers which are in communication with one another.

A single-stage carbon dioxide multi-split cooling and heating multifunctional central air conditioner, comprising a single-stage carbon dioxide circulation system using carbon dioxide as a circulation working medium; the single-stage carbon dioxide circulation system comprises an outdoor unit and a plurality of end heat exchangers provided in parallel; and the carbon dioxide medium performs cooling and/or heating in a circulating manner in a carbon dioxide compressor, an outdoor heat exchanger, a liquid storage tank and the end heat exchangers which are in communication with one another.

A gas turbine engine has a compressor section, a combustor, and a turbine section. An associated fluid is to be cooled and an associated fluid is to be heated. A transcritical vapor cycle heats the fluid to be heated, and cools the fluid to be cooled. The transcritical vapor cycle includes a gas cooler in which the fluid to be heated is heated by a refrigerant in the transcritical vapor cycle. An evaporator heat exchanger at which the fluid to be cooled is cooled by the refrigerant in the transcritical vapor cycle. A compressor upstream of the gas cooler compresses the refrigerant to a pressure above a critical point for the refrigerant. An expansion device expands the refrigerant downstream of the gas cooler, with the evaporator heat exchanger being downstream of the expansion device, and such that the refrigerant passing through the gas cooler to heat the fluid to be heated is generally above the critical point.

An air cycle machine includes an air inlet connected to an air cycle compressor. Air downstream of the air cycle compressor is connected to be delivered across a first turbine. The air cycle compressor is driven by the first turbine through a shaft. Air downstream of the first turbine is connected to a second turbine. The second turbine is connected to deliver air downstream. The second turbine is connected with a second shaft to drive a fan rotor. The fan rotor delivers a source of air across a primary heat exchanger positioned between the inlet and the air cycle compressor. The air cycle compressor and the first turbine are formed of a metal. The second turbine and the fan rotor are formed of non-metallic materials.

An apparatus includes a captured carbon dioxide input. The captured carbon dioxide input is coupled to receive captured carbon dioxide from a direct air capture system. The apparatus uses the captured carbon dioxide as a low global warming refrigerant to provide cooling functionality in automotive, commercial, and industrial applications, or other operations involving low global warming refrigerants. In various embodiments, the apparatus is a refrigeration apparatus or a heat pump apparatus. Low global warming carbon dioxide refrigerant is natural, non-toxic, non-flammable, and abundant when obtained from a direct air capture system. Moreover, carbon dioxide refrigerant has a high heat transfer coefficient and has a global warming potential (GWP) of one. Carbon dioxide refrigerant is a more sustainable and efficient coolant option than common refrigerants, such as R22, R152, R404a, and R1234yf refrigerants.

A refrigerant composition comprising carbon dioxide (CO.sub.2; R-744) and from 1 to 32 weight % difluoromethane (R-32) based on the total weight of the composition is described. Also described is the use of the refrigerant composition for providing heating and cooling and a refrigeration, air-conditioning or heat pump system comprising the refrigerant composition.

A cooling system includes an ingress port to receive refrigerant in a vapor form from an evaporator, an egress port to return refrigerant in a liquid form back to the evaporator, a condenser coupled to the ingress port and the egress port, and a compressor coupled to the ingress port and the condenser. When the cooling system operates in a first mode, the condenser is configured to receive and condense the refrigerant from the vapor form into the liquid form and to return the refrigerant in the liquid form to the regress port. When the cooling system operates in a second mode, the compressor is configured to compress the refrigerant in the vapor form and to supply the compressed refrigerant to the condenser to be condensed therein.

A system includes a pressure exchanger (PX). The PX is coupled to a motor that controls an operating speed of the PX. The system further includes a first pressure gauge configured to generate first pressure data indicative of a pressure of a fluid of a condenser. A first controller is to generate a first control signal based on the first pressure data. The motor of the PX is configured to adjust the operating speed of the PX based on the first control signal. The system further includes a pump. The system further includes a fluid density sensor for generating fluid density data associated with a first output fluid of the PX. A second controller is to generate a second control signal based on at least the fluid density data. The pump is to adjust an operating speed of the pump based on the second control signal.

A thermal management system is described. The thermal management system includes a receiver configured to store a refrigerant, the receiver having a receiver inlet and a receiver outlet, a closed-circuit refrigeration system including a vapor compression closed-circuit system that includes the receiver, and a closed-circuit system that includes the receiver, wherein the closed-circuit refrigeration system is configurable to receive refrigerant from the receiver through one or both of the vapor compression closed-circuit system and the closed-circuit system.