Aspects of the present disclosure include a system for turbo-compression cooling. The system may be aboard a marine vessel. The system includes a power cycle and a cooling cycle. The power cycle includes a first working fluid, a waste heat boiler configured to evaporate the working fluid, a turbine, and a condenser. The condenser condenses the working fluid to a saturated or subcooled liquid. The cooling cycle includes a second working fluid, a first compressor configured to increase the pressure of the second working fluid, a condenser configured to condense the second working fluid to a saturated or subcooled liquid after exiting the first compressor, an expansion valve, and an evaporator. The turbine and first compressor are coupled one to the other. The waste heat boiler receives waste heat from engine jacket water and lubricating oil from a ship service generator. The evaporator cools water in a shipboard cooling loop.

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).

An object of the present invention is to provide, as a working fluid to be used for a heat cycle system, a working fluid for heat cycle that has cycle performance replaceable with that of R410A, and at the same time, has a small burden on an apparatus, low flammability, suppressed self-decomposition, and less effect on global warming, and therefore, is usable stably even if leaked, a composition for heat cycle system containing the same, and a heat cycle system using the composition. The working fluid for heat cycle contains trifluoroethylene, difluoromethane, and at least one selected from 1,1-difluoroethane, fluoroethane, propane, propylene, carbon dioxide, 2,3,3,3-tetrafluoropropene, and (E)-1,3,3,3-tetrafluoropropene at mass ratios satisfying predetermined expressions and at a ratio of the total content to be 90 to 100 mass % relative to the total amount of the working fluid and has a temperature glide of 10° C. or less.

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.

The propagation of a disproportionation reaction of a refrigerant is suppressed. Disclosed is a method that uses a composition in a device, in which the composition includes one or more compounds selected from the group of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropene, and 1,3,3,3-tetrafluoropropene, and the heat capacity of a portion with a melting point greater than or equal to 1,000° C. in the device is greater than or equal to 6.5 J/K.

The propagation of a disproportionation reaction of a refrigerant is suppressed. Disclosed is a method that uses a composition as a refrigerant in a compressor, in which the composition includes one or more compounds selected from the group of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropene, and 1,3,3,3-tetrafluoropropene, the compressor forms a refrigerant circuit together with first to ninth refrigerant pipes, a gas-side refrigerant communication pipe, and a liquid-side refrigerant communication pipe, and the compressor includes first to fifth heat absorbing portions in each of which a heat capacity of a portion with a melting point greater than or equal to 1,000° C. is greater than or equal to 6.5 J/K.

The present invention provides a composition comprising a refrigerant (mixed refrigerant) having three types of performance, i.e., a coefficient of performance (COP) and refrigerating capacity (Cap) that are equivalent to or higher than those of R410A, and a sufficiently low GWP. Specifically, the present invention provides a composition comprising a refrigerant, the refrigerant comprising CF.sub.3I, CO.sub.2 (R744), and at least one compound A selected from the group consisting of trifluoroethylene (HFO-1123), trans-1,2-difluoroethylene [(E)-HFO-1132], cis-1,2-difluoroethylene [(Z)—HFO-1132], fluoroethylene (HFO-1141), and 3,3,3-trifluoropropyne (TFP).

An ejector refrigeration cycle device includes: a radiator that dissipates heat from a refrigerant discharged from a compressor; an ejector module that decompresses the refrigerant cooled by the radiator; and an evaporator that evaporates a liquid-phase refrigerant separated in a gas-liquid separation space of the ejector module. A grille shutter is disposed as an inflow-pressure increasing portion between the radiator and a cooling fan blowing the outside air toward the radiator. The grille shutter is operated to decrease the volume of the outside air to be blown toward the radiator when an outside air temperature is equal to or lower than a reference outside air temperature, thereby increasing the pressure of the inflow refrigerant to flow into a nozzle passage of the ejector module.

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.

A heat exchanger includes at least one flat tube configured to allow a refrigerant mixture inclusive of HFO1123, R32, and HFO1234yf to flow therethrough as a heat medium. The flat tube includes a plurality of flow paths for the heat medium. Each of the plurality of flow paths has a round rectangular shape in cross section, the round rectangular shape being defined by a pair of longitudinal line segments opposed to each other, a pair of lateral line segments opposed to each other, and a set of four rounded corners, each of the rounded corners being a segment of a circumference of a circle. The pair of longitudinal line segments are intersects with the pair of lateral line segments at the rounded corners. The round rectangular shape is configured to satisfy 0.005≦r/d≦0.8 where r is a radius of the circle, and d is a distance between the pair of longitudinal line segments opposed to each other.