An air-conditioning apparatus includes an outdoor-side flow rate control device (a fourth flow rate control device) that generates an intermediate pressure for injection into a compressor, and a bypass flow rate control device (a sixth flow rate control device) that is placed at a bypass pipe allowing bypassing of an outdoor heat exchanger in parallel to the outdoor-side flow rate control device and that controls the amount of heat exchange of the outdoor heat exchanger together with the outdoor-side flow rate control device.

An air-conditioning apparatus includes a heat medium system configured to control a flow rate of the heat medium supplied to the heat source unit side heat exchanger that exchanges heat between refrigerant and the heat medium, the heat medium system having at least one system of a heat medium conveyor, a heat medium flow rate adjuster, and a heat medium flow rate control device. In the air-conditioning apparatus, the operation of each of use-side heat exchangers is changed to a cooling operation or a heating operation in accordance with a control command, and a cooling and heating concurrent operation is performed. The refrigerant is caused to flow through the heat source unit side heat exchanger in accordance with the ratio of the total cooling capacity of the use-side heat exchangers to the total heating capacity of the use-side heat exchangers. The heat medium flow rate control device controls the flow rate of the heat medium supplied to the heat source unit side heat exchanger, using the temperature of the heat medium flowing into the heat source unit side heat exchanger and the temperature of the heat medium flowing from the heat source unit side heat exchanger.

A heat-medium flow-path switching device and a heat-medium flow-rate adjusting device are integrated into an integrated heat-medium flow-rate adjusting device. The integrated heat-medium flow-rate adjusting device is configured to perform the heat-medium flow-path switching function and the meat-medium flow-rate adjusting function by driving and controlling a single drive unit. Moreover, the integrated heat-medium flow-path switching device is configured to perform a function of closing flow paths from/to a use-side heat exchanger added to the heat-medium flow-rate adjusting function.

An air-conditioning apparatus includes a compressor, an indoor heat exchanger configured to function as a condenser or an evaporator, indoor heat exchanges each configured to function as a condenser or an evaporator, a plurality of expansion valves each provided for a corresponding one of the indoor heat exchangers each configured to adjust a flow rate of a refrigerant that flows through the corresponding indoor heat exchanger, and a controller configured to control an operation capacity of the compressor and opening degrees of a plurality of expansion devices. When increasing heat exchange performance of the indoor heat exchanger, the controller increases the operation capacity of the compressor and controls the opening degree of the expansion valve corresponding to the indoor heat exchanger to decrease the flow rate of the refrigerant that flows through the indoor heat exchanger.

An air-conditioning apparatus includes a bypass pipe that has one end connected to the discharge side of a compressor and through which refrigerant exiting the compressor flows, an auxiliary heat exchanger that is connected to the other end of the bypass pipe and the suction part of the compressor, and cools refrigerant flowing through the bypass pipe and supplies the cooled refrigerant to the suction part of the compressor, and a flow regulating unit that is provided on the refrigerant outlet side of the auxiliary heat exchanger, and regulates the flow rate of refrigerant routed into the suction part of the compressor from the auxiliary heat exchanger.

A multi-room air-conditioning apparatus includes an outdoor unit, a relay unit connected to an outdoor unit by first and second connection pipes, and a plurality of indoor units connected to the relay unit. The outdoor unit includes a second gas-liquid separating device provided on the suction side of the compressor. The suction side of the compressor and the second gas-liquid separating device are connected to each other by a gas-side outlet pipe and a liquid-side outlet pipe.

An air-conditioning apparatus includes a refrigerant circuit including a low-pressure shell structure compressor into which a refrigerant flowing through an injection pipe flows, a first heat exchanger, a second heat exchanger, a first expansion device, a refrigerant flow switching device, and a second expansion device configured to allow the refrigerant which has passed through the first expansion device and flows from the second heat exchanger to the first heat exchanger to have an intermediate pressure, the compressor, the first heat exchanger, the second heat exchanger, the first expansion device, the refrigerant flow switching device, and the second expansion device being connected by pipes to constitute the refrigerant circuit, and further includes a controller that controls an amount of refrigerant flowing through the injection pipe into a compression chamber. A part of a high-pressure refrigerant flowing from the first heat exchanger to the second heat exchanger flows through the injection pipe.

An air-conditioning apparatus includes a heat medium circuit with a heat medium flow reversing device that can switch the flow direction of a heat medium in the heat medium side passage of the heat exchanger related to heat medium.

A computing device calculates a quality of a refrigerant flowing out of an expansion device on the basis of an inlet liquid enthalpy calculated on the basis of a temperature of the refrigerant flowing into the expansion device, and a saturated gas enthalpy and a saturated liquid enthalpy calculated on the basis of a temperature or pressure of the refrigerant flowing out of the expansion device; calculates a liquid-phase concentration and a gas-phase concentration of the refrigerant flowing out of the expansion device on the basis of the temperature and pressure of the refrigerant flowing out of the expansion device; and calculates a composition of the refrigerant circulating in a refrigeration cycle on the basis of the calculated quality, liquid-phase concentration, and gas-phase concentration.

A flow rate of circulating water to a water heat exchanger is determined by multiplying, by a rated water flow rate, a ratio of an absolute value of a difference between a total operation capacity of each of indoor side heat exchangers serving as a heating load and a total operation capacity of each of indoor side heat exchangers serving as a cooling load to a total operation capacity of the water heat exchanger.