A refrigeration apparatus uses R32 as refrigerant, and includes a compressor, a condenser, an expansion mechanism, an evaporator, a branch flow channel branching from a main refrigerant channel joining the condenser and the evaporator, a first opening adjustable valve disposed along the branch flow channel, an injection heat exchanger, a first injection channel, a refrigerant storage tank disposed along the main refrigerant channel, and a second injection channel. The injection heat exchanger exchanges heat between refrigerant in the main refrigerant channel and refrigerant passing through the first opening adjustable valve. The first injection channel guides refrigerant that flows in the branch flow channel and that exits from the injection heat exchanger to the compressor or the suction passage. The second injection channel guides a gas component of refrigerant accumulated inside the refrigerant storage tank to the compressor or the suction passage.

An air-conditioning apparatus has a heating only temporary operation mode in which, in changing from a heating main operation mode to a heating only operation mode, when an outside air temperature is at or above a predetermined temperature, at least one of heat exchangers functioning as a condenser in the heating main operation mode continues functioning as the condenser, and the refrigerant is not supplied to the intermediate heat exchanger functioning as an evaporator in the heating main operation mode and a cooling only temporary operation mode in which, in changing from a cooling main operation mode to a cooling only operation mode, when the outside air temperature is at or below a predetermined temperature, at least one of heat exchangers functioning as the evaporator in the cooling main operation mode continues functioning as the evaporator, and the refrigerant is not supplied to the intermediate heat exchanger functioning as the condenser in the cooling main operation mode.

An air-conditioning apparatus directly detects leakage of a plurality of types of refrigerant by computing refrigerant concentrations, and ensure safety. On the basis of calibration curve information, a computing device computes the concentration of heat source side refrigerant in a heat medium relay unit from detected information received from a concentration detecting device.

An air-conditioning apparatus has a controller that sets the target value of a difference between the temperatures of a secondary-side heat transfer medium at positions before and after a plurality of use side heat exchangers during a rated operation in a heating operation so as to have a larger magnitude than a target value of the difference between the temperatures of the secondary-side heat transfer medium at positions before and after the plurality of use side heat exchangers during a rated operation in the cooling operation.

A flow reversing device is provided for a heating, ventilation, air conditioning, and refrigeration (HVACR) system having a heat exchanger. The flow reversing device included a first flow control device, a second flow control device, a third flow control device, and a fourth flow control device, each flow control device being a two-way flow control device. When the first flow control device and the fourth flow control device are opened and the second flow control device and the third flow control device are closed, a first flow is formed. When the second flow control device and the third flow control device are opened and the first flow control device and the fourth flow control device are closed, a second flow is formed. The first flow and the second flow are in opposite directions.

A refrigeration cycle system includes: a heat source circuit including a secondary-side compressor, a cascade heat exchanger, a secondary-side switching mechanism, and a suction flow path; a plurality of utilization circuits respectively including utilization-side heat exchanger; a first communication pipe; a second communication pipe; a third communication pipe; a connection path; and a first on-off valve. The first communication pipe and the first heat source pipe connect the plurality of utilization-side heat exchangers and the secondary-side switching mechanism. The second communication pipe and the second heat source pipe connect the plurality of utilization-side heat exchangers and suction flow path. The third communication pipe, the fourth heat source pipe, and the fifth heat source pipe connect the plurality of utilization-side heat exchangers and the cascade heat exchanger. The connection path connects the first communication pipe and the second communication pipe. The first on-off valve switches between a state in which the first communication pipe and the second communication pipe connect and a state in which they do not connect.