A refrigeration cycle apparatus that can improve operation efficiency when a refrigerant that contains at least 1,2-difluoroethylene is used is provided. An air conditioning apparatus 1 includes a compressor (21), an outdoor heat exchanger (23), an outdoor expansion valve (24), an indoor heat exchanger (31), and a suction injection pipe (40), and uses a refrigerant that contains at least 1,2-difluoroethylene. The suction injection pipe (40) allows a part of a refrigerant that flows toward the indoor heat exchanger (31) from the outdoor heat exchanger (23) to merge with a low-pressure refrigerant that is sucked into the compressor (21).

An air conditioning apparatus 1 includes a compressor (321), an indoor heat exchanger (242) that is a use-side heat exchanger that exchanges heat with first air (F1), an outdoor heat exchanger (323) that is a heat-source-side heat exchanger that exchanges heat with second air, a refrigerant, a first duct (209), and a casing (230). The refrigerant contains at least 1,2-difluoroethylene, and circulates in the compressor (321), the indoor heat exchanger (242), and the outdoor heat exchanger (323) to repeat a refrigeration cycle. The first duct (209) supplies the first air (F1) to a plurality of rooms in an interior. The casing (230) includes a use-side space (SP2) that is connected to the first duct (209) and that accommodates the indoor heat exchanger (242). The casing (230) is configured to allow the first air (F1) after heat exchange with the refrigerant at the indoor heat exchanger (242) to be sent out to the first duct (209).

To reduce the possibility that temperature of refrigerant discharged from a compressor of a refrigeration apparatus becomes excessively high by controlling torque of a motor built into the compressor, the compressor includes the motor having rotation thereof controlled by inverter control. An inverter controller controls torque of the motor using inverter control when operation frequency of the compressor is at least one value within a range of from 10 Hz to 40 Hz. When at least the operation frequency is within the range of from 10 Hz to 40 Hz, torque of the motor is controlled, and under a predetermined condition in which temperature of refrigerant discharged from the compressor easily becomes excessively high, a device controller controls devices provided in a refrigerant circuit such that refrigerant sucked into the compressor is placed in a wet vapor state.

An air-conditioning apparatus includes: a heat source unit that generates a heating energy or a cooling energy that is transferred to refrigerant; a heat-use unit that causes the refrigerant to transfer the heating energy or the cooling energy to a heat load through heat exchange between the refrigerant and the heat load; a plurality of return pipes arranged parallel to each other and connecting the heat source unit and the heat-use unit to allow the refrigerant to flow therein from the heat-use unit to the heat source unit; an opening and closing device provided at at least one of the return pipes to control a flow rate of refrigerant; and a controller that opens the opening and closing device in a cooling operation, and closes the opening and closing device in a heating operation.

An air-conditioning system includes a heat source unit, an air conditioner connected via piping to the heat source unit and configured to perform heat exchange between water supplied by the heat source unit and indoor air, a water circulation device for circulating the water between the heat source unit and the air conditioner, and an air-conditioning control device. The air-conditioning control device controls the heat source unit to lower temperature of the water flowing into the air conditioner, in accordance with an increase in an indoor humidity, and controls the water circulation device to lower temperature of the water flowing from the air conditioner back to the heat source unit, in accordance with an increase in an indoor temperature.

A refrigeration cycle apparatus includes a refrigeration cycle circuit, a bypass flow path, a first valve provided in the refrigeration cycle circuit, a second valve provided at the bypass flow path, a first temperature sensor configured to detect a temperature of an indoor space, a second temperature sensor configured to detect a temperature of refrigerant on a liquid side of an indoor heat exchanger, and a notification part. The refrigeration cycle apparatus is able to operate in an operation state where the compressor operates, the indoor heat exchanger functions as an evaporator, and the first valve is open while the second valve is closed. In the operation state, the notification part issues notification of an abnormality of an electronic expansion valve or the first valve when a temperature detected by the second temperature sensor is higher than an evaporation temperature of refrigerant in the refrigeration cycle circuit.

A method of operating an air conditioner unit, as provided herein, includes initiating a first heat pump cycle, the first heat pump cycle comprising sending a control signal to the fan to rotate at a predetermined rotational speed, and detecting an actual rotational speed of the fan, calculating a first flow rate of air through the first heat exchanger based on the control signal and the actual rotational speed, storing the first flow rate as a first reference flow rate, stopping the first heat pump cycle, initiating a second heat pump cycle, calculating a second flow rate of air through the first heat exchanger, comparing the calculated second flow rate to the first reference flow rate, and directing the air conditioner unit based on the comparison of the calculated second flow rate to the first reference flow rate.

An outdoor unit of an air-conditioning apparatus includes an outdoor unit main body, a compressor, an outdoor heat exchanger, an outdoor fan, an outdoor air temperature detection unit, and a control unit. The control unit stores an outdoor air temperature that is detected when the outdoor unit main body receives an operation stop signal, a temperature determination unit configured to determine whether the outdoor air temperature stored in the storage unit is less than a temperature threshold value when the outdoor unit main body receives an operation start signal, and an operation timing setting unit configured to select an operation mode of the compressor based on an outdoor air temperature detected by the outdoor air temperature detection unit after operation of the outdoor fan is resumed in a case where the temperature determination unit determines that the outdoor air temperature is less than the temperature threshold value.

A system comprising a compressor, a first valve coupled to the compressor and coupled to a first coil, a first expansion valve coupled to the first coil, a second coil, and a second expansion valve. The second expansion valve coupled to a third coil, a second valve coupled to the compressor and the third coil. A controller operable to operate the first valve, the first expansion valve, the second expansion valve, and the second valve. The second coil is coupled to the compressor and the refrigerant flows from the second coil to the compressor.

A system includes a compressor, an indoor fan, a thermostat, an indoor fan controller, and a compressor controller. The thermostat provides first and second signals based on indoor loading. The fan controller operates the fan in low speed mode and the compressor controller operates the compressor in low capacity mode when only the first signal is asserted. The compressor controller automatically switches the compressor to high capacity mode if only the first signal remains asserted past the low capacity mode runtime. The fan controller operates the fan in high speed mode when the second signal is asserted while the first signal is still asserted. The compressor controller continues to operate the compressor in high capacity mode and the fan controller operates the fan in low speed mode after the second signal is de-asserted, until the first signal is de-asserted, at which point the fan and compressor are turned off.