It is determined whether thermo-off postponement control is allowed or not on the basis of a current compressor operating frequency when a thermo-off condition is satisfied. If it is determined that thermo-off postponement control is allowed, the thermo-off postponement control in which a lowest operating frequency in an operating frequency range of a compressor is temporarily reduced within a range greater than or equal to a minimum operating frequency of the compressor in use so as to continue an operation. If it is determined that thermo-off postponement control is not allowed, thermo-off of stopping the compressor is performed.

A refrigeration cycle apparatus includes a refrigeration cycle in which refrigerant circulates, the refrigeration cycle including a compressor, an outdoor heat exchanger, expansion valves, and indoor heat exchangers, which are connected to each other via a refrigerant pipe, a heat source unit accommodating the outdoor heat exchanger, use-side units accommodating the indoor heat exchangers, and a control unit that controls at least turning on and off of the refrigeration cycle. The control unit detects abnormality of the refrigeration cycle based on the pressure or temperature of the refrigeration cycle in an off time of the refrigeration cycle.

In a case of a heating operation in which the use side heat exchanger functions as a condenser when an outside temperature is a predetermined low temperature, a low-outside-temperature heating operation start-up mode in which, while a refrigerant discharged from the compressor is caused to flow into the use side heat exchanger, a refrigerant is supplied to the injection port of the compressor via the injection pipe and part of the refrigerant that has transferred heat in the heat source side heat exchanger is supplied to the compressor, is followed by a low-outside-temperature heating operation mode in which the refrigerant discharged from the compressor is supplied to the injection port of the compressor via the injection pipe while the refrigerant being caused to flow into the use side heat exchanger.

A CPU 110 compares the extracted outside air temperature with a first low pressure saturation temperature. When the outside air temperature is lower than the first low pressure saturation temperature, the CPU 110 switches a first three-way valve 22 and a second three-way valve 23 so that a second outdoor heat exchanger 25 is used as a condenser and that a first outdoor heat exchanger 24 is not used. When the outside air temperature is higher than a second low pressure saturation temperature which is the first low pressure saturation temperature to which a predetermined temperature is added, the CPU 110 switches the first three-way valve 22 and the second three-way valve 23 so that the first outdoor heat exchanger 24 is used as a condenser and that the second outdoor heat exchanger 25 is not used.

A channel on an upstream side of a third expansion device and a channel on an upstream side of a second expansion device are connected during a heating operation, and medium pressure refrigerant generated by the third expansion device during the heating operation is introduced on a suction side of a compressor via the second expansion device and a suction injection pipe.

An icemaking system includes a circulation circuit configured to circulate icemaking solution, at least one icemaker provided in the circulation circuit, a cooling mechanism, a first detector and an adjuster. The icemaker includes a cooling chamber and a scraping mechanism. The cooling chamber has an inflow port and an exhaust port of solution, and the cooling chamber allows the solution to flow in the cooling chamber. The scraping mechanism scrapes ice generated on an inner surface of the cooling chamber. The cooling mechanism cools the solution in the cooling chamber. The first detector detects whether the inflow port of the cooling chamber has an ice nucleus. The adjuster adjusts a cooling temperature of the solution in accordance with a detection result of the first detector.

An air conditioning apparatus includes a first refrigerant circuit enclosing a first refrigerant, and a second refrigerant circuit enclosing a second refrigerant. The first refrigerant circuit includes a compressor configured to compress the first refrigerant, an outdoor heat exchanger, an expansion device, and a first flow path through which the first refrigerant passes in an intermediate heat exchanger configured to exchange heat between the first refrigerant and the second refrigerant. The second refrigerant circuit includes a pump configured to increase a pressure of the second refrigerant and transfer the second refrigerant, a second flow path through which the second refrigerant passes in the intermediate heat exchanger, and an indoor heat exchanger. At least one of the first refrigerant and the second refrigerant has a global warming potential lower than that of R32, and the second refrigerant has a lower flammable limit concentration higher than that of the first refrigerant.

A refrigeration cycle apparatus includes a refrigerant circuit in which a compressor, a first heat exchanger, a first expansion device, a second expansion device, and a second heat exchanger are connected by refrigerant pipes and through which refrigerant circulates, an accumulator provided to the refrigerant circuit, formed to store liquid refrigerant, and from which gas refrigerant is caused to be sucked into the compressor, a liquid-level sensing device provided to the accumulator and sensing a liquid level of the liquid refrigerant stored in the accumulator, and a controller performs, in a case in which the liquid level sensed by the liquid-level sensing device is higher than a threshold, a limiting operation of reducing an amount of suction of the gas refrigerant that is sucked from the accumulator into the compressor and, in a case in which the liquid level is lower than or equal to the threshold, a normal operation.

A multi-connected heat recovery air conditioning system and a control method thereof. The multi-connected heat recovery air conditioning system includes an indoor unit, an outdoor unit and a hydraulic module, wherein the outdoor unit comprises a compressor, an outdoor heat exchanger, a first four-way valve and a second four-way valve. The multi-connected heat recovery air conditioning system further comprises an indoor unit temperature unit, a water temperature unit, a high-pressure sensor and a low-pressure sensor. The indoor unit temperature unit is arranged in the indoor unit for detecting and obtaining the outlet temperature value of the indoor unit, the water temperature unit is arranged at a heat exchange water tank for detecting and obtaining water temperature, and the high-pressure sensor and the low-pressure sensor are arranged at the output end and the air return end of the compressor respectively.

A heat pump system including a charge compensator having a liquid line port for an inflow of a refrigerant into the charge compensator and for an outflow of the refrigerant from the charge compensator. The heat pump system further includes an isolation valve configured to control flows of the refrigerant to and from the charge compensator through a liquid line piping of the heat pump system based on whether the heat pump system is operating in a cooling mode, a defrost mode, or a heating mode, where the liquid line port is fluidly coupled to the liquid line piping of the heat pump system.