Abstract: In the case of a heating operation in which a use side heat exchanger functions as a condenser when the outside air has a predetermined low temperature, a low-outside-air-temperature heating operation start mode is executed in which, while a refrigerant, as discharged from a compressor, flows into the use side heat exchanger, the refrigerant, upon flowing into the injection pipe, merges with a part of the refrigerant discharged from the compressor, which has traveled through the connecting pipe and has transferred heat in the heat source side heat exchanger, and a merged refrigerant is supplied to the injection port of the compressor, and thereafter a low-outside-air-temperature heating operation mode is executed in which the refrigerant, as discharged from the compressor, is supplied to the injection port of the compressor via the injection pipe while flowing into the use side heat exchanger.

Abstract: 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.

Abstract: A refrigeration cycle apparatus includes a refrigerant circuit of a refrigeration cycle through which a refrigerant that transits in a supercritical state is allowed to flow, and a flow dividing device that divides the flow of a high-pressure liquid refrigerant in a subcritical state into two or more parts. The flow dividing device is configured such that the device is oriented substantially in the horizontal direction or substantially upward in the vertical direction relative to the direction of flow of the refrigerant in a liquid state. With such a configuration, the flow of refrigerating machine oil is equally divided, thus offering high energy saving while keeping heat-medium conveyance power at a low level without reducing the heat exchanging performance.

Abstract: An air-conditioning apparatus including a refrigeration cycle configured by connecting one or more load-side units including a load-side heat exchanger and a load-side expansion device with a heat-source-side unit including a heat-source-side heat exchanger and a compressor and by causing refrigerant to circulate through a refrigerant circuit including the load-side heat exchanger, the load-side expansion device, the heat-source-side heat exchanger, and the compressor, controls, during a heating operation, the opening degree of the load-side expansion device, based on the discharge pressure of the compressor, so that the pressure of refrigerant at the outlet of the compressor becomes equal to a target pressure, in the case where the operation capacity of the compressor is approximately at the maximum value of the operation capacity of the compressor.

Abstract: An air-conditioning apparatus is capable of completing heat medium freeze prevention control more quickly by performing heat medium temperature rise control for raising the temperature of a cooled heat medium and includes a controller that adjusts a current opening degree of a bypass device at a bypass pipe to an opening degree, and that makes an adjustment such that the flow passage resistance in the case of the opening degree becomes equal to the flow passage resistance in the case of an opening degree before an expansion device is adjusted to a minimum opening degree.

Abstract: A refrigeration cycle apparatus includes a refrigerant circuit of a refrigeration cycle through which a refrigerant that transits in a supercritical state is allowed to flow, and a flow dividing device that divides the flow of a high-pressure liquid refrigerant in a subcritical state into two or more parts. The flow dividing device is configured such that the device is oriented substantially in the horizontal direction or upward in the vertical direction relative to the direction of flow of the refrigerant in a liquid state. With such a configuration, the flow of refrigerating machine oil is equally divided, thus offering high energy saving while keeping heat-medium conveyance power at a low level without reducing the heat exchanging performance.

Abstract: A heat source-side refrigerant circuit A including a compressor 11, an outdoor heat exchanger 13, a first refrigerant branch portion 21 connected to the compressor 11, a second refrigerant branch portion 22 and a third refrigerant branch portion 23 connected to the outdoor heat exchanger 13, a first refrigerant flow rate control device 24 provided between branch piping 40 and the second refrigerant branch portion 22, intermediate heat exchangers 25n connected at one side thereof to the first refrigerant branch portion 21 and the third refrigerant branch portion 23 via three-way valves 26n and connected at the other side thereof to the second refrigerant branch portion 22, and second refrigerant flow rate control devices 27n provided between the respective intermediate heat exchangers 25n and the second refrigerant branch portion 22, and user-side refrigerant circuits Bn having indoor heat exchangers 31n connected respectively to the intermediate heat exchangers 25n are provided, and at least one of water and

Abstract: In an air-conditioning apparatus, a heat source side heat exchanger, intermediate heat exchangers, and use side heat exchangers are separately formed and adapted to be disposed at separate locations, respectively. There is provided a defrosting operation function to melt frost attached around the heat source side heat exchanger, and a heating function during defrosting operation that drives a pump to circulate a heat medium and supply heating energy to the use side heat exchangers in need of heating to perform heating operation. The defrosting operation function can be executed by switching a four-way valve to cooling side to introduce a high-temperature high-pressure refrigerant flowed out of the compressor into the heat source side heat exchanger.

Abstract: An air-conditioning apparatus includes: an outdoor unit including a compressor, a first refrigerant flow path switching device, and a heat-source-side heat exchanger; a heat medium relay unit including an intermediate heat exchanger, an expansion device, a second refrigerant flow path switching device, and a pump; and at least one indoor unit including a use-side heat exchanger. The compressor, the first refrigerant flow path switching device, the expansion device, the second refrigerant flow path switching device, and the intermediate heat exchanger are connected using a refrigerant pipe, thereby making up a refrigeration cycle. The intermediate heat exchanger and the use-side heat exchanger are connected using a heat medium pipe, thereby making up a heat medium circulation circuit in which a heat medium different from the refrigerant circulates.

Abstract: An air-conditioning apparatus includes a suction-injection pipe that introduces a refrigerant in a liquid or two-phase state into a suction side of a compressor, an expansion device that is arranged at the suction-injection pipe, and a controller that regulates the suction-injection flow rate of a refrigerant introduced into the suction side of the compressor through the suction-injection pipe by controlling the opening degree of the expansion device.

Abstract: 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.

Abstract: In an air-conditioning apparatus, a heat source side heat exchanger 12, intermediate heat exchangers 15a and 15b, and use side heat exchangers 26a to 26d are separately formed and adapted to be disposed at separate locations, respectively. There are provided a defrosting operation function to melt frost attached around the heat source side heat exchanger 12, and a heating function during defrosting operation that drives a pump 21a to circulate a heat medium and supply heating energy to the use side heat exchangers 26a to 26d in need of heating to perform heating operation. The defrosting operation function can be executed by switching a four-way valve 11 to cooling side to introduce a high-temperature high-pressure refrigerant flowed out of the compressor 10 into the heat source side heat exchanger 12.

Abstract: In a refrigeration cycle device, a design volume ratio, obtained by dividing a stroke volume of a sub-compressor by a stroke volume of an expander, is set to be smaller than (DE/DC)×hE?hF)/(hB?hA). With an operating efficiency being the maximum in an operating range allowed to be set of the refrigeration cycle device, DE is a density of a refrigerant, which has flowed out from a radiator, DC is a density of the refrigerant, which has flowed out from an evaporator, hE is a specific enthalpy of the refrigerant flowing into the expander, hF is a specific enthalpy of the refrigerant, which has flowed out from the expander, hA is a specific enthalpy of the refrigerant sucked by a main compressor, and hB is a specific enthalpy of the refrigerant at an intermediate position of a compression process of the main compressor.

Abstract: A compact, readily-manufacturable heat exchanger and a refrigeration cycle apparatus equipped with the same are provided. One of opposite ends of a main body in a refrigerant flowing direction is provided with a first inlet communication hole that extends in a direction of arrangement of first refrigerant channels and that communicates with all of the first refrigerant channels. The other end is provided with a first outlet communication hole that extends in the direction of arrangement of the first refrigerant channels and that communicates with all of the first refrigerant channels.

Abstract: A heat exchanger in which inner wall surfaces of refrigerant passages through which a first refrigerant and a second refrigerant flow are constituted by a different metal and in which a heat exchange performance is improved. Second-refrigerant heat-transfer tubes that are formed with a metal different from a heat transfer block are each inserted through a corresponding second-refrigerant heat-transfer-tube insertion hole. The second-refrigerant heat-transfer tubes are formed with a metal with a different material from that of the heat transfer block.

Abstract: An outdoor unit is configured to include a compressor and a heat source side heat exchanger. Indoor units are configured to include first expansion devices and use side heat exchangers, and air-condition an air-conditioned space. Branching devices, connected by pipes to the outdoor unit by a plurality of main pipes and connected by pipes to each indoor unit by a plurality of branch pipes, are configured to branch a refrigerant from a side of the main pipes and circulate the refrigerant to the branch pipes, and converge the refrigerant from a side of the branch pipes and circulate the refrigerant to the main pipes. A refrigerant concentration detecting device is installed in a non-air-conditioned space. A shutoff valve control device is configured, upon determining that the refrigerant has leaked, to control shutoff devices and to shut off the refrigerant flows.

Abstract: A refrigeration cycle apparatus includes a refrigerant circuit of a refrigeration cycle through which a refrigerant that transits in a supercritical state is allowed to flow, and a flow dividing device that divides the flow of a high-pressure liquid refrigerant in a subcritical state into two or more parts. The flow dividing device is configured such that the device is oriented substantially in the horizontal direction or substantially upward in the vertical direction relative to the direction of flow of the refrigerant in a liquid state. With such a configuration, the flow of refrigerating machine oil is equally divided, thus offering high energy saving while keeping heat-medium conveyance power at a low level without reducing the heat exchanging performance.

Abstract: In an air-conditioning apparatus that uses a refrigerant, which operates in a transcritical cycle, and refrigerating machine oil, which has low miscibility with the refrigerant, in a refrigerant circuit for a refrigeration cycle connected to a compressor, a radiator, an expansion mechanism, and an evaporator, the air-conditioning apparatus includes a flow regulating mechanism provided in the refrigerant circuit, and flow control means that controls the flow regulating mechanism. If a refrigerant flow velocity at an outlet side of the radiator is lower than a predetermined threshold value, the refrigerant flow velocity at the outlet side of the radiator is increased by the flow control means so that oil-return operation that returns the refrigerating machine oil discharged from the compressor to the compressor is performed for at least a predetermined time period.

Abstract: A refrigeration cycle apparatus increases the cooling capacity even under overload conditions in a refrigeration cycle apparatus that uses a refrigerant which undergoes transition to a supercritical state and in which the high-pressure side enters a supercritical state. A refrigeration cycle apparatus adjusts a high-pressure-side pressure of a refrigerant flowing through a main refrigerant circuit by causing a controller to control an opening degree of a second expansion valve and a heat transfer area of a radiator.

Abstract: A refrigeration cycle apparatus achieves efficient operation by constantly recovering power in a wide operating range. The refrigeration cycle apparatus regulates a pressure of a high pressure side by changing either one or both of an opening degree of the intermediate-pressure bypass valve and an opening degree of the pre-expansion valve on the basis of a density ratio that is obtained from an inflow refrigerant density of the expander and an inflow refrigerant density of the sub-compressor in an actual operating state and a design volume ratio that has been expected at the time of design and that is obtained from a stroke volume of the sub-compressor, a stroke volume of the expander, and a ratio of a flow rate of the refrigerant flowing to the sub-compressor.