Abstract: An air-conditioning apparatus includes a main circuit in which a compressor, a refrigerant flow switching device, a load side heat exchanger, a load side expansion device, and a plurality of heat source side heat exchangers are sequentially connected. When the plurality of heat source side heat exchangers are used as condensers, the first heat source side heat exchanger and the second heat source side heat exchanger are connected in series. When the plurality of heat source side heat exchangers are used as evaporators, the first heat source side heat exchanger and the second heat source side heat exchanger are connected in parallel. A distribution adjustment header on an inlet side of at least either the first heat source side heat exchanger or the second heat source side heat exchanger when the plurality of heat source side heat exchangers are used as evaporators.

Abstract: A heat exchanger group includes a first heat exchanger, a second heat exchanger, and a third heat exchanger. In a cooling operation, refrigerant discharged from the compressor is divided into two. One refrigerant is delivered to the second heat exchanger, and the other refrigerant is delivered to the third heat exchanger. The second heat exchanger performs heat exchange to turn the refrigerant into two-phase refrigerant. The third heat exchanger performs heat exchange to turn the refrigerant into two-phase refrigerant. The refrigerant that has flowed through the second heat exchanger and the refrigerant that has flowed through the third heat exchanger meet, and the resultant refrigerant is delivered to the first heat exchanger. The first heat exchanger performs heat exchange, so that the two-phase refrigerant turns into liquid refrigerant and flows through the first heat exchanger.

Abstract: 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.

Abstract: An air-conditioning apparatus includes a refrigerant circuit in which pipes sequentially connect a compressor, a flow switching device, a heat source side heat exchanger, an expansion device, a load side heat exchanger, and the flow switching device, and configured to perform a cooling operation and a heating operation switched by the flow switching device, an oil separator configured to separate refrigerating machine oil from refrigerant discharged from the compressor, a first bypass passage in which fluid flowing out of the oil separator flows, an auxiliary heat exchanger configured to cool the fluid, a first flow control device configured to control passing of the fluid, a second bypass passage in which liquid refrigerant or two-phase gas-liquid refrigerant flowing through one of the pipes connecting the heat source side heat exchanger and the expansion device flows, and a second flow control device configured to control passing of refrigerant.

Abstract: An air-conditioning apparatus includes a refrigerant circuit formed by connecting, with pipes, a compressor to compress refrigerant and discharge the compressed refrigerant, a first heat exchanger, a subcooling heat exchanger exchanges heat between a portion of the refrigerant flowing in a first flow passage and another portion of the refrigerant flowing in a second flow passage to subcool the portion of refrigerant flowing in the first flow passage, a first expansion device to decompress the refrigerant, a second heat exchanger, and an accumulator connected to a suction side of the compressor and configured to store excess refrigerant, so that the refrigerant is circulated through the refrigerant circuit. The air-conditioning apparatus is configured to prevent the discharge temperature of the compressor from being excessively increased irrespective of the operation mode and therefore prevent damage to the compressor.

Abstract: An air-conditioning apparatus is capable of efficiently performing defrosting operation without suspending a heating operation of an indoor unit. The air-conditioning apparatus includes a main circuit sequentially connecting, via a pipe, a compressor, indoor heat exchangers, first flow control devices, and a plurality of parallel heat exchangers connected in parallel to each other to allow refrigerant to circulate, first defrost pipes branching a part of the refrigerant discharged from the compressor and causing the part of the refrigerant to flow into one of the plurality of parallel heat exchangers and to be defrosted, an interface heat exchanger located between the plurality of parallel heat exchangers, a first bypass pipe branching a part of the refrigerant discharged from the compressor and causing the part of the refrigerant to flow into the interface heat exchanger, and a second bypass pipe causing the part of the refrigerant flowing out of the interface heat exchanger to flow into the main circuit.

Abstract: An air-conditioning apparatus divides an outdoor heat exchanger to form parallel heat exchangers and supplies part of refrigerant from a compressor to the parallel heat exchangers alternately to perform defrosting, performs medium-pressure defrosting in which part of the refrigerant from the compressor is decompressed and supplied to a parallel heat exchanger to be subjected to defrosting, and the refrigerant after being used for defrosting is injected into the compressor. A first flow switching unit performs switching of a connection mode of ends of the parallel heat exchangers on compressor side, where the pressure changes among high pressure, medium pressure, and low pressure according to operation contents, to one of three modes: a mode with the ends connected to the compressor discharge side, a mode with the ends connected to the compressor suction side, and a mode with the ends connected to neither the discharge nor suction side.

Abstract: An outdoor unit, connected with indoor units by pipes to constitute a refrigerant circuit, includes a compressor configured to compress and discharge refrigerant, a plurality of parallel heat exchangers configured to allow heat exchange between air and the refrigerant, a first defrosting pipe serving as a flow path for branching a part of the refrigerant discharged by the compressor and allowing the refrigerant to flow into the parallel heat exchanger to be defrosted for defrosting, a first expansion device configured to decompress the refrigerant passing through the first defrosting pipe, a second expansion device configured to adjust the pressure of the refrigerant that passed through the parallel heat exchanger to be defrosted, and a controller configured to control the second expansion device such that the pressure of the refrigerant that passed through the parallel heat exchanger to be defrosted falls within a predetermined range.

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 includes a main circuit in which a compressor, an indoor heat exchanger, a first flow control device, and a plurality of parallel heat exchangers connected in parallel to each other are sequentially connected via a pipe to allow refrigerant to circulate, a first defrost pipe that branches a part of the refrigerant discharged from the compressor and allows the refrigerant to flow into the parallel heat exchanger to be defrosted among the plurality of parallel heat exchangers, a expansion device provided in the first defrost pipe and configured to depressurize the refrigerant discharged from the compressor, and a connection switching device that allows the refrigerant flowing out of the parallel heat exchanger to be defrosted to flow into the main circuit at a position upstream of the parallel heat exchangers other than the parallel heat exchanger subject to defrosting.

Abstract: To provide an air-conditioning apparatus that is safer and has small conveying power for such as water at the indoor unit side can be made small. It is characterized in that a compressor 10 and a heat source side heat exchanger 12 are accommodated in a heat source apparatus 1, an intermediate heat exchanger 15 and a pump 21 in a relay unit 3, a use side heat exchanger 26 in an indoor unit 2, respectively, and when a controller 60 makes the compressor 10 stop based on the thermo-off due to decrease in the heat load in the use side heat exchanger 26 or an operation stop instruction, the controller 60 makes the pump 21 stop after the compressor 10 is stopped or almost at the same time as the stop.

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: An air-conditioning apparatus achieves improvement of safety and further achieves saving of energy without allowing a refrigerant to circulate in or near an indoor unit. The air-conditioning apparatus is configured such that heat medium pipes have a larger inner cross-sectional area per unit capacity than that of refrigerant pipes.

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 a refrigerant circuit formed by connecting pipes, a compressor including a compression chamber and an injection port through which refrigerant is introduced into the compression chamber, a first heat exchanger, a subcooling heat exchanger that includes a first flow passage and a second flow passage and exchanges heat between refrigerant flowing in the first flow passage and refrigerant flowing in the second flow passage to subcool the refrigerant flowing in the first flow passage, a first expansion device, a second heat exchanger, and an accumulator In addition, a first bypass pipe connects the second flow passage of the subcooling heat exchanger with a segment of the pipes, positioned on a refrigerant inflow side of the accumulator; an expansion device to adjust a flow rate of the refrigerant flowing in the first bypass pipe; a second bypass pipe that connects a segment of the pipes with the injection port, the segment being positioned between the first heat exchanger a

Abstract: An air-conditioning apparatus includes a selection unit and a determination unit, the selection unit selecting a reverse-defrosting operation mode or a heating-defrosting simultaneous operation mode, the reverse-defrosting operation mode being a mode in which all of parallel heat exchangers are defrosted by stopping a heating operation, the heating-defrosting simultaneous operation mode being a mode in which each parallel heat exchanger is sequentially defrosted while continuing a heating operation, the determination unit determining whether or not a defrosting operation is to be started, in which the determination unit is configured to start the defrosting operation in a state where the amount of frost deposited on the parallel heat exchangers is smaller in a case where the heating-defrosting simultaneous operation mode is selected than in a case where the reverse-defrosting operation is selected.

Abstract: A refrigeration cycle apparatus including a heat source side heat exchanger including a first heat exchanger and a second heat exchanger connected in parallel; an air-sending device that supplies air, which is an object to be heat exchanged in the first heat exchanger and the second heat exchanger, in a variable manner; solenoid valves that each opens and closes a refrigerant passage of the first heat exchanger and the second heat exchanger; a third refrigerant circuit that is parallelly connected to the first heat exchanger and the second heat exchanger; and a flow control valve that controls the flow rate of the refrigerant flowing in the third refrigerant circuit. The refrigeration cycle apparatus can improve continuity of control of a heat exchange capacity of a heat source side heat exchanger.

Abstract: 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.

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: In an air-conditioning apparatus, a heat source side heat exchanger, intermediate heat exchangers, and use side heat exchangers are formed in separate bodies respectively and adapted to be disposed at separate locations one another. In a heat medium circulation circuit where the intermediate heat exchanger and the use side heat exchanger are connected, temperature sensors are installed. An anti-freezing operation mode is provided in which, when the detection temperatures of the temperature sensors become equal to or lower than a set temperature Ts while a compressor or pumps are stopped, the heat medium is circulated to perform anti-freezing of the heat medium.