Abstract: An air-conditioning apparatus includes: a plurality of heat source units each including a compressor, a heat-source-side heat exchanger, a flow control valve, and an accumulator; a use-side load connected to the heat source units by pipes, and including a use-side heat exchanger that causes heat exchange to be performed between refrigerant supplied from each of the heat source units and a use-side heat medium; and a controller that controls an operation of each of the heat source units. The controller includes a determination unit and a liquid equalization unit. The determination unit determines whether or not a current operation is a non-normal operation in which the heat source units and the use-side load operate in a different manner from that in a heating operation or a cooling operation. The liquid equalization unit equalizes the amounts of liquid refrigerant that flows in the heat source units, when the determination unit determines that the current operation is the non-normal operation.

Abstract: An air-conditioning apparatus includes heat-source-side units each including a compressor and a heat-source-side heat exchanger, a load-side heat exchanger and a load-side expansion device, a first header, a second header, bypass expansion devices, circuit switching units, discharge pressure sensors, bypass pressure sensors, and a controller configured to control, in a heat-source-side unit in defrosting mode, the circuit switching unit in such a manner that a portion of refrigerant discharged from the compressor flows into the heat-source-side heat exchanger and configured to control, in the heat-source-side unit in defrosting mode, an opening degree of the bypass expansion device in the heat-source-side unit in such a manner that a value representing a difference between a value obtained by the discharge pressure sensor and a value obtained by the bypass pressure sensor is equal to or greater than a predetermined value.

Abstract: An air-conditioning apparatus includes: a first defrosting pipe branching from a main circuit to supply a portion of refrigerant discharged from a compressor to one of plural parallel heat exchangers to be defrosted; a second defrosting pipe which returns, to the main circuit, the refrigerant supplied through the first defrosting pipe to the one parallel heat exchanger; a first expansion device provided on the first defrosting pipe; a second expansion device provided on the second defrosting pipe to adjust a pressure of the refrigerant in the one parallel heat exchanger; and a third expansion device provided between a connection point between an outlet of the second defrosting pipe and the main circuit and one of plural indoor heat exchangers functioning as an evaporator, to adjust a pressure of the refrigerant in the one of the indoor heat exchangers; and a controller that controls the second and third expansion devices individually.

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 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 includes heat-source-side units each including a compressor and a heat-source-side heat exchanger, a load-side heat exchanger and a load-side expansion device, a first header, a second header, bypass expansion devices, circuit switching units, discharge pressure sensors, bypass pressure sensors, and a controller configured to control, in a heat-source-side unit in defrosting mode, the circuit switching unit in such a manner that a portion of refrigerant discharged from the compressor flows into the heat-source-side heat exchanger and configured to control, in the heat-source-side unit in defrosting mode, an opening degree of the bypass expansion device in the heat-source-side unit in such a manner that a value representing a difference between a value obtained by the discharge pressure sensor and a value obtained by the bypass pressure sensor is equal to or greater than a predetermined value.

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 controller switches between and performs a first simultaneous heating and defrosting operation of supplying part of refrigerant discharged from a compressor is supplied to one or some parallel heat exchangers among a plurality of parallel heat exchangers through a defrosting circuit and allowing the other one or more parallel heat exchangers to operate as evaporators, and a second simultaneous heating and defrosting operation of, in one or some heat source units among a plurality of heat source units, supplying the refrigerant discharged from the compressor is supplied to all the plurality of parallel heat exchangers through the defrosting circuit, and in the other one or more heat source units, continuing heating by allowing all the plurality of parallel heat exchangers to operate as evaporators.

Abstract: A controller switches between and performs a first simultaneous heating and defrosting operation of supplying part of refrigerant discharged from a compressor is supplied to one or some parallel heat exchangers among a plurality of parallel heat exchangers through a defrosting circuit and allowing the other one or more parallel heat exchangers to operate as evaporators, and a second simultaneous heating and defrosting operation of, in one or some heat source units among a plurality of heat source units, supplying the refrigerant discharged from the compressor is supplied to all the plurality of parallel heat exchangers through the defrosting circuit, and in the other one or more heat source units, continuing heating by allowing all the plurality of parallel heat exchangers to operate as evaporators.

Abstract: An air-conditioning apparatus includes: a first defrosting pipe branching from a main circuit to supply a portion of refrigerant discharged from a compressor to one of plural parallel heat exchangers to be defrosted; a second defrosting pipe which returns, to the main circuit, the refrigerant supplied through the first defrosting pipe to the one parallel heat exchanger; a first expansion device provided on the first defrosting pipe; a second expansion device provided on the second defrosting pipe to adjust a pressure of the refrigerant in the one parallel heat exchanger; and a third expansion device provided between a connection point between an outlet of the second defrosting pipe and the main circuit and one of plural indoor heat exchangers functioning as an evaporator, to adjust a pressure of the refrigerant in the one of the indoor heat exchangers; and a controller that controls the second and third expansion devices individually.

Abstract: Provided is an air-conditioning apparatus capable of performing a cooling and heating mixed operation, including: a heat source unit including a compressor; a plurality of indoor units; a relay unit; a first relay unit-side bypass pipe configured to cause a part of refrigerant, which is discharged from the compressor and flows into the relay unit, to flow between a heat source unit-side heat exchanger and an indoor unit-side heat exchanger; a second relay unit-side flow rate control device provided to the first relay unit-side bypass pipe; and a controller configured to control an opening degree of the second relay unit-side flow rate control device so that, in an operation in which the heat source unit-side heat exchanger functions as an evaporator, a discharge temperature of a discharge refrigerant discharged from the compressor is equal to or lower than a heat-resistant temperature of 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-cooled air-conditioning apparatus including a heat source side heat exchanger comprising a plural number of heat source side heat exchanger parts that are connected together, and each of the heat source side heat exchanger parts is connected by a corresponding flow switching valve to a compressor. The air-cooled air-conditioning apparatus includes a controller configured to perform a defrosting operation in which a refrigerant discharged from the compressor is caused to flow separately through each of the heat source side heat exchanger parts by opening and closing the corresponding flow switching valves. The controller performs the defrosting operation on the basis of the heat exchanger capacity of each of the heat source side heat exchanger parts, the necessary heating capacity of each of the heat source side heat exchanger parts, and the arrangement of the heat source side heat exchanger parts.

Abstract: An air-conditioning apparatus includes a time constant calculation unit that estimates a response time constant at a time when an opening degree of an expansion device is changed on the basis of specifications of a compressor that forms a refrigeration cycle of the air-conditioning apparatus, specifications of a load side heat exchanger, and an operating state quantity of the air-conditioning apparatus, a control constant calculation means that calculates at least one of a control gain of the opening degree of the expansion device and a control interval on the basis of a calculation result of the time constant calculation means, and a control constant change means that changes a control constant.

Abstract: An outdoor heat exchanger includes a fan configured to adjust a heat transfer coefficient ao of the outside of a heat transfer tube through which a refrigerant flows, a bypass passage and flow rate control valve configured to adjust a heat transfer coefficient ?i of the inside of the heat transfer tube through which the refrigerant flows, and an on-off valve configured to adjust a heat transfer area A where the refrigerant exchanges heat with a heat medium. A controller controls the heat transfer coefficient ?o of the outside of the heat transfer tube, the heat transfer coefficient ?i of the inside thereof, and the heat transfer area A to control a heat exchange amount of the outdoor heat exchanger.

Abstract: An air-conditioning apparatus includes an injection pipe allowing a part of a refrigerant, as discharged from a compressing device, to flow into an intermediate portion of a compression stroke of the compressing device, and an injection internal heat exchanger that exchanges heat between a refrigerant stream that flows through the injection pipe and a refrigerant stream that flows into a heat-source-side heat exchanger after passing through an indoor unit.

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 heat-source-side unit includes a body case having an air inlet and an air outlet, a heat exchanger contained in the body case and disposed to an air passage between the air inlet and the air outlet, and a damper disposed above the heat exchanger and configured to open and close the air passage. The damper is closed in a defrosting operation that removes frost on the heat exchanger.

Abstract: Provided is an air-conditioning apparatus capable of performing a cooling and heating mixed operation, including: a heat source unit including a compressor; a plurality of indoor units; a relay unit; a first relay unit-side bypass pipe configured to cause a part of refrigerant, which is discharged from the compressor and flows into the relay unit, to flow between a heat source unit-side heat exchanger and an indoor unit-side heat exchanger; a second relay unit-side flow rate control device provided to the first relay unit-side bypass pipe; and a controller configured to control an opening degree of the second relay unit-side flow rate control device so that, in an operation in which the heat source unit-side heat exchanger functions as an evaporator, a discharge temperature of a discharge refrigerant discharged from the compressor is equal to or lower than a heat-resistant temperature of the compressor.

Abstract: An air-conditioning apparatus includes an injection pipe allowing a part of a refrigerant, as discharged from a compressing device, to flow into an intermediate portion of a compression stroke of the compressing device, and an injection internal heat exchanger that exchanges heat between a refrigerant stream that flows through the injection pipe and a refrigerant stream that flows into a heat-source-side heat exchanger after passing through an indoor unit.