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.

Abstract: A multi-chamber air conditioner including a heat-source side refrigerant circuit in which a compressor, an outdoor heat exchanger, a first heat exchanger, a refrigerant flow-rate controller, and a second heat exchanger are connected in series, a first use-side refrigerant circuit in which the first heat exchanger and an indoor heat exchanger are connected in series, and a second use-side refrigerant circuit in which the second heat exchanger and the indoor heat exchanger are connected in series, and a heat-source side refrigerant circulating in the heat-source side refrigerant circuit and a use-side refrigerant circulating in the use-side refrigerant circuit are heat-exchanged in the first heat exchanger. The heat-source side refrigerant circulating in the heat-source side refrigerant circuit and the use-side refrigerant circulating in the use-side refrigerant circuit are heat-exchanged in the second heat exchanger.

Abstract: An air-conditioning apparatus including, a first housing (an outdoor unit) that accommodates a compressor and a heat source side heat exchanger; a second housing (a heat medium relay unit) that accommodates a heat exchanger related to heat medium, an expansion device, and a pump; a third housing (a heat medium regulating unit) that accommodates a first heat medium flow switching device, a second heat medium flow switching device, and a heat medium flow control device; and a fourth housing (indoor unit) that accommodates a use side heat exchanger have separately different casings.

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 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: 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 controller 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 controller 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: 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: 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: Disclosed is a positive displacement expander equipped with an expansion mechanism in which power is generated using fluid energy produced while a high-pressure fluid, supplied to a plurality of expansion chambers partitioned by an orbiting scroll or a rolling piston, is being expanded and decompressed. The expander includes a communicating pipe that allows each of the expansion chambers to communicate with an expander discharge side and an opening and closing device disposed on the communicating pipe. When supply of the high-pressure fluid is stopped, the opening and closing device is opened by the time when high and low pressures between each of the expansion chambers and the expander discharge side are equalized, thus stopping the orbiting scroll or the rolling piston at a predetermined position so that an expander obtains sufficient driving force when resuming.

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: 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: In order to provide a refrigeration cycle device that is compact and efficiently utilizing an expansion machine and reduced in manufacturing cost through the use of a first compressor and second compressor driven by an expansion machine, a heat radiator and an on-off valve are disposed between the first and the second compressors and the second heat radiator is utilized irrespective of the operating mode such as the cooling or heating operation. Also, the heat transfer area ratio, which is a ratio of the heat transfer area of the second heat source side heat exchanger relative to the total heat transfer area of the heat transfer areas of said first and second heat source side heat exchangers, is set, according to the air speed distribution, within a range at which the COP is at its peak. Thus, the second heat source side heat exchanger can be utilized even during the heating operation, providing a high efficiency refrigeration cycle device.

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: 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 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.

Abstract: Obtained is an air-conditioning apparatus that is capable of saving energy. A pressure in a passage of the second refrigerant flow switching device in which a refrigerant from an outdoor unit flows into is higher than a pressure in a passage of the second refrigerant flow switching device in which the refrigerant flows out to the outdoor unit regardless of switching states of a first refrigerant flow switching device, the second refrigerant flow switching devices, and a third refrigerant flow switching device.

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 is supplied to the injection port of the compressor via an injection pipe and a part of a refrigerant that is accumulated in an accumulator is supplied to the compressor via a connecting pipe, 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: In the invention, control of the expansion device is carried out based on the temperature difference between the refrigerant temperature of the first representative point that becomes a predetermined enthalpy under the refrigerant pressure of the gas cooler and the detection temperature of the outlet temperature sensor, and control of the rotation speed of the compressor and/or the rotation speed of the heat medium sending device is/are carried out based on the second representative point that is, under the refrigerant pressure of the gas cooler, a temperature different from the first representative point.

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: 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.