A heat exchanger within an insulated enclosure receives primary refrigerant at a high pressure and cools the primary refrigerant using a secondary refrigerant from a secondary refrigeration system. An expansion unit within the insulated enclosure receives the primary refrigerant at the high pressure from the heat exchanger and discharges the primary refrigerant at a low pressure. A supply line delivers the primary refrigerant at the low pressure to the load and a return line returns the primary refrigerant from the load to the primary refrigeration system. A system control unit controls operation of at least one of the primary refrigeration system and the secondary refrigeration system to provide a variable refrigeration capacity to the load based on at least one of: a pressure of the primary refrigerant delivered to the load, and at least one temperature of the load.

Disclosed are methods for providing heating and/or cooling of the type comprising evaporating refrigerant liquid and condensing refrigerant vapor in a plurality of repeating cycles, where the method comprises (a) providing the refrigerant comprising at least about 5% by weight of a lower alkyl iodofluorocarbon; and (b) exposing at least a portion of said refrigerant in at least a portion of said plurality of said cycles to a sequestration material comprising: i) copper or a copper alloy; ii) a molecular sieve (preferably a zeolite), comprising copper, silver, lead or a combination thereof; iii) an anion exchange resin, and iv) a combination of two or more of these, wherein said exposing temperature is preferably above about 20 C.

The present disclosure addresses the problem of providing a refrigerant composition that has a low GWP and a refrigerating capacity equivalent to that of R404A, which is currently widely used. As a solution to the problem, the present disclosure provides a composition containing carbon dioxide and a mixture of fluorinated hydrocarbons, the mixture containing difluoromethane (R32), pentafluoroethane (R125), 2,3,3,3-tetrafluoropropene (R1234yf), 1,1,1,2-tetrafluoroethane (R134a), and carbon dioxide (CO.sub.2) in specific concentrations.

The present disclosure provides a mixed refrigerant having four types of performance, i.e., an excellent coefficient of performance and refrigerating capacity that allow it to serve as an alternative refrigerant for R410A, a sufficiently low GWP, and non-flammability. Specifically, the present disclosure provides a composition comprising a refrigerant, the refrigerant comprising trifluoroiodomethane (CF.sub.3I) and difluoromethane (R32), wherein the contents of CF.sub.3I and R32 in the refrigerant are respectively 48 mass %≥CF.sub.3I≥46 mass % and 54 mass %≥R32≥52 mass %, based on the total amount of CF.sub.3I and R32 taken as 100 mass %.

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 refrigeration cycle apparatus (10) includes a refrigerant circuit (11) including a compressor (12), a heat source-side heat exchanger (13), an expansion mechanism (14), and a usage-side heat exchanger (15). In the refrigerant circuit (11), a refrigerant containing at least 1,2-difluoroethylene (HFO-1132 (E)) is sealed. At least during a predetermined operation, in at least one of the heat source-side heat exchanger (13) and the usage-side heat exchanger (15), a flow of the refrigerant and a flow of a heating medium that exchanges heating with the refrigerant are counter flows.

The present invention provides cascade refrigeration systems in which the low stage comprises a refrigerant with a GWP less than 150, and the high stage comprises a refrigerant that is either Class A1 or Class A2L and comprises at least about 75% by weight of HFO-1234ze(E).

Disclosed are refrigerants and refrigeration systems, including cascade refrigeration sysemsar comprising: a plurality of refrigeration units, each refrigeration unit containing a first refrigeration circuit, each first refrigeration circuit comprising an evaporator and a heat exchanger; and a second refrigeration circuit; wherein each first circuit heat exchanger is arranged to transfer heat energy between its respective first refrigeration circuit and the second refrigeration circuit.

A vapor compression refrigeration system, including a reciprocating, scroll, or rotary compressor and a refrigerant composition. The refrigerant composition comprises difluoromethane (R-32), 2,3,3,3-tetrafluoropropene (R-1234yf), and propane (R-290).

The present application relates to compositions (e.g., heat transfer fluids) for use in refrigeration and heat transfer applications. The compositions of the present invention are useful in methods for producing cooling and heating, and methods for replacing refrigerants and refrigeration, air conditioning, and heat pump apparatuses.