A heat pump device includes an inverter control unit outputting PWM signals to an inverter; a current detection unit detecting a current value flowing in the inverter and outputting the current value after reducing a current value having a first frequency or higher in detected current value; and a drive-signal stop unit that, when the current value output from the current detection unit is equal to or larger than an interruption level, stops output of PWM signals to the inverter. Particularly, the inverter control unit generates a voltage command value such that the voltage command value becomes a value equal to or larger than a lower limit determined according to the first frequency and generates PWM signals based on generated voltage command value and a carrier signal, thereby causing a voltage output time to the motor to be a predetermined time or longer.

The invention relates to a refrigerant circuit (10) of a vehicle air-conditioning system (12), in particular for electric vehicles, comprising a compressor unit (14) which includes a first compressor (16) and a second compressor (18) arranged downstream for compressing a refrigerant (20), a condenser (22) for heating air (24) which can be supplied to a vehicle interior, a first pressure reducing unit (26) arranged downstream of the condenser (22) for decompressing the refrigerant (20) from the condenser (22), a heat exchanger (28) through which refrigerant flows for heat exchange with vehicle ambient air (30), an evaporator (32) for cooling air (24) which can be supplied to a vehicle interior, and a second pressure reducing unit (34) arranged upstream of the evaporator (32) for decompressing the refrigerant (20) from the heat exchanger (28), the second compressor (18), the condenser (22) and the first pressure reducing unit (26) being bypassed in a cooling mode of the vehicle air-conditioning system (12), and the evaporator (32) and the second pressure reducing unit (34) being bypassed in a heating mode of the vehicle air-conditioning system (12). The invention furthermore relates to a method of air-conditioning a vehicle interior, in particular by means of the refrigerant circuit (10) described above.

A method including: determining a cooling value; and comparing the cooling value to an activation point of a lead compressor. The lead compressor is in a tandem set of scroll compressors of a cooling system. The tandem set of compressors comprises a lag compressor. The method further includes: activating the lead compressor when the cooling value is greater than the activation point; activating the lag compressor subsequent to activating the lead compressor; and determining whether conditions exist including: an alarm associated with the lag compressor being generated, and the lead compressor being deactivated. The method further includes deactivating the lag compressor when at least one of the conditions exists in the cooling 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 transportation refrigeration unit (TRU) system is provided and includes a damper assembly configured to direct air flows through first or second pathways and an evaporator disposed in the first pathway, a coil element surrounded by phase change material (PCM) and disposed in the second pathway and a routing assembly configured to direct refrigerant through the evaporator or the coil element. With the PCM pre-cooled, the damper and routing assemblies are controllable to respectively direct the air flows through the first pathway and the refrigerant through the evaporator when first conditions are met and to respectively direct the air flows through the second pathway when second conditions are met.

A transportation refrigeration unit (TRU) system is provided and includes a damper assembly configured to direct air flows through first or second pathways and an evaporator disposed in the first pathway, a coil element surrounded by phase change material (PCM) and disposed in the second pathway and a routing assembly configured to direct refrigerant through the evaporator or the coil element. With the PCM pre-cooled, the damper and routing assemblies are controllable to respectively direct the air flows through the first pathway and the refrigerant through the evaporator when first conditions are met and to respectively direct the air flows through the second pathway when second conditions are met.

A device for use in a refrigeration or heat pump system. A device includes an outer casing which includes a longitudinal cylindrical shell and end plates arranged at both ends of the shell, and at least three units of the refrigeration or heat pump system arranged inside the same common outer casing, which units are selected from the group consisting of an evaporator, a superheater, an economizer, a condenser, a desuperheater, a sub-cooler and an oil cooler.

A heat pump includes an evaporator with an evaporator inlet and an evaporator outlet; a compressor for compressing operating liquid evaporated in the evaporator; and a condenser for condensing evaporated operating liquid compressed in the compressor, wherein the condenser includes a condenser inlet and a condenser outlet, wherein the evaporator inlet is connected to a return from a region to be heated, and wherein the condenser inlet is connected to a return from a region to be cooled.

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.

The lubricating oil composition for a refrigerator of the present invention is a lubricating oil composition for a refrigerator that is used in combination with a refrigerant containing at least one fluorine-containing organic compound selected from compounds represented by the following molecular formula (A):

C.sub.pF.sub.rR.sub.s  (A)

wherein R represents Cl, Br, I, or H; p represents an integer of from 2 to 6; r represents an integer of from 1 to 12; and s represents an integer of from 0 to 11, provided that the molecule contains at least one carbon-carbon unsaturated bond, and the lubricating oil composition for a refrigerator contains a base oil and a cyclic organic compound having a cyclic hydrocarbon structure and having one or more non-conjugated double bond in a cyclic structure or a side chain thereof.