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.

An object is to provide a novel low-GWP mixed refrigerant. Provided is a composition comprising a refrigerant, the refrigerant comprising difluoromethane (R32), trans-1,2-difluoroethylene (HFO-1132(E)), 1,3,3,3-tetrafluoropropene (R1234ze), and 1,1-difluoroethylene (HFO-1132a).

There is described an air conditioning system with a refrigerant circuit, wherein the air conditioning system includes a leakage detection system. The leakage detection system comprises a room temperature sensor, an inlet temperature sensor for detection of a refrigerant temperature at a refrigerant inlet of a refrigerant evaporator, and an outlet temperature sensor for detection of a refrigerant temperature at a refrigerant outlet of the refrigerant evaporator. The sensors (34, 36, 40) are coupled with a calculating unit. In addition, there is described a method for leakage detection, in which a room temperature of the room to be air-conditioned is detected before the refrigerant evaporator on an air inlet side, a refrigerant inlet temperature is detected at the refrigerant inlet of a refrigerant evaporator, and a refrigerant outlet temperature is detected at a refrigerant outlet of the refrigerant evaporator.

To provide a composition for a hat cycle system which comprises a working fluid containing 1,1,2-trifluoroethylene, having cycle performance sufficient as an alternative to R410A while suppressing influence over global warming, and a heat cycle system employing the composition. A composition for a heat cycle system, which comprises a working fluid for heat cycle containing 1,1,2-trifluoroethylene, CF.sub.3I and at least one compound selected from a hydrofluorocarbon, a hydrofluoroolefin other than 1,1,2-trifluoroethylene and a hydrocarbon, and having a temperature glide of at most 7° C., and a heat cycle system employing the composition for a heat cycle system.

A working fluid for heat cycle, a composition for a heat cycle system containing the working fluid, and a heat cycle system employing the composition are provided. The working fluid has a low global warming potential and can replace R410A. The working fluid contains trifluoroethylene and 2,3,3,3-tetrafluoropropene. The total proportion of trifluoroethylene and 2,3,3,3-tetrafluoropropene based on the entire amount of the working fluid is from 70 to 100 mass %. The proportion of trifluoroethylene based on the total amount of trifluoroethylene and 2,3,3,3-tetrafluoropropene is from 35 to 95 mass %.

A refrigerant gas sensor is typically attached so that an opening for introducing leaked refrigerant gas into the inside faces upward. With this arrangement, however, a small amount of a different gas such as propane and pesticide, which is sucked from the outside of an air conditioner, may be erroneously recognized as refrigerant gas. On this account, a refrigerant gas sensor 9 includes a detecting element 61 for detecting leakage of refrigerant gas and a casing member 62 provided to surround the detecting element 61. The casing member 62 has a casing opening (first opening) 62a through which the refrigerant gas is introduced into the inside of the casing member 62. The casing opening (first opening) 62a is below the detecting element 61.

An air conditioner which continues driving with a deteriorated gas leakage sensor is provided. An air conditioner of the present invention includes an outdoor unit including a compressor and an indoor unit connected with the outdoor unit and uses flammable refrigerant. The air conditioner includes: a refrigerant gas sensor; and a controlling unit configured to stop the compressor at occurrence of abnormality, when the refrigerant gas sensor detects refrigerant gas while the compressor is being driven. After the compressor is stopped as the refrigerant gas sensor detects the refrigerant gas, the controlling unit does not start driving of the compressor until an operation to cancel the abnormality is performed.

An indoor unit includes an air-sending fan, an air inlet through which air of an indoor space is sucked in, and an air outlet located above the air inlet and through which the air sucked in through the air inlet is blown out to the indoor space. A control unit activates the air-sending fan when leakage of the refrigerant is detected. When M [kg] represents an amount of charge of the refrigerant in a refrigeration cycle, LFL [kg/m.sup.3] represents a lower flammable limit of the refrigerant, A [m.sup.2] represents a floor area of the indoor space, and Ho [m] represents a height of the air outlet above a floor surface of the indoor space, the amount of charge M, the lower flammable limit LFL, the floor area A, and the height Ho satisfy a relationship of M<LFL×A×Ho.

An ice making machine having a refrigeration system designed for hydrocarbon (HC) refrigerants, and particularly propane (R-290), that includes dual independent refrigeration systems and a unique evaporator assembly comprising of a single freeze plate attached to two cooling circuits. The serpentines are designed in an advantageous pattern that promotes efficiency by ensuring the even bridging of ice during freezing and minimizing unwanted melting during harvest by providing an even distribution of the heat load. The charge limitations imposed with flammable refrigerants would otherwise prevent large capacity ice maker from being properly charged with a single circuit. The ice making machine includes a single water circuit and control system to ensure the proper and efficient production of ice. Material cost is conserved as compared to a traditional dual system icemaker.

To provide a composition for a hat cycle system which comprises a working fluid containing 1,1,2-trifluoroethylene, having cycle performance sufficient as an alternative to R410A while suppressing influence over global warming, and a heat cycle system employing the composition.

A composition for a heat cycle system, which comprises a working fluid for heat cycle containing 1,1,2-trifluoroethylene, CF.sub.3I and at least one compound selected from a hydrofluorocarbon, a hydrofluoroolefin other than 1,1,2-trifluoroethylene and a hydrocarbon, and having a temperature glide of at most 7° C., and a heat cycle system employing the composition for a heat cycle system.