To provide a refrigeration cycle device that has a refrigerant flow path with a structure to form a counter flow of air and refrigerant not only during cooling, but also during heating, and that allows low-pressure two-phase refrigerant to flow through a liquid pipe and can thereby reduce the amount of refrigerant needed. The refrigeration cycle device includes: an outdoor unit 1 including a compressor 5, a four-way valve 6, an outdoor heat exchanger 7, and an outdoor expansion valve 9, the four-way valve 6 being configured to switch between cooling operation and heating operation; an indoor unit 2 including an indoor heat exchanger 12 and an indoor expansion valve 14; and a gas pipe 3 and a liquid pipe 4 configured to connect the outdoor unit 1 and the indoor unit 2; and at least either one of a first bridge circuit 10 having a configuration including a plurality of flow path opening-closing units 11 to allow the refrigerant to flow through the outdoor heat exchanger 7 in the same direction both during the cooling operation and during the heating operation, and a second bridge circuit 15 having a configuration including a plurality of flow path opening-closing units 16 to allow the refrigerant to flow through the indoor heat exchanger 12 in the same direction both during the cooling operation and during the heating operation.

Air conditioner units and methods of operating the same are provided. A method of operating an air conditioner unit includes determining a fan speed as a function of a compressor speed of a variable speed compressor of the air conditioner unit. The method also includes activating a variable speed fan of the air conditioner unit at the fan speed. An air conditioner unit may include a controller, and the controller may be configured for performing the method.

A refrigeration system includes a compressor for compressing a gaseous refrigerant, such that the temperature and pressure thereof increases; a four-way valve controlling whether the refrigeration system is in a heating mode or a cooling mode; a condenser, in which the gaseous refrigerant from the compressor exchanges heat with a high temperature heat carrier, said heat exchange resulting in the refrigerant condensing; an expansion valve reducing the pressure of liquid refrigerant from the condenser, hence reducing the boiling point of the refrigerant; an evaporator, in which the low boiling point refrigerant exchanges heat with a low temperature heat carrier, such that the refrigerant vaporizes; and a suction gas heat exchanger exchanging heat between high temperature liquid refrigerant from the condenser and low temperature gaseous refrigerant from the evaporator. A balance valve is arranged for controlling the amount of heat exchange between the high temperature liquid refrigerant and the low temperature gaseous refrigerant in the suction gas heat exchanger by directing a flow of high temperature liquid refrigerant directly from the condenser to the expansion valve. Disclosed is also a method for controlling such a system.

A refrigeration cycle apparatus includes: a first refrigerant route; and a second refrigerant route. In the first refrigerant route, refrigerant flows in order of a compressor, a first heat exchanger, a first pipe, a second heat exchanger, a low pressure receiver and the compressor. The second refrigerant route is connected to the first pipe and the low pressure receiver, the first pipe being connected to the first heat exchanger and the second heat exchanger in the first refrigerant route. The second refrigerant route includes an electric pump. The electric pump is configured to flow the refrigerant from the low pressure receiver to the first pipe.

A refrigeration cycle apparatus comprises: a compressor; a first heat exchanger; a second heat exchanger; a first decompressing apparatus; an oil separator; a first circulation pathway in which a refrigerant circulates in an order of the compressor, the first heat exchanger, the oil separator, the first decompressing apparatus, and the second heat exchanger; an oil-returned pathway connecting between the oil separator and a suction side of the compressor; a second decompressing apparatus provided in the oil-returned pathway; and a controller configured to control the first decompressing apparatus and the second decompressing apparatus. The controller is configured to set an operation mode to an oil collection mode by adjusting a degree of decompression of the first decompressing apparatus and a degree of decompression of the second decompressing apparatus when the refrigerant and a refrigerating machine oil flowing in the first circulation pathway are separated in the oil separator.

A heat pump system includes a compressor, a usage side heat exchanger, a heat source side heat exchanger, an expansion mechanism, a main refrigerant flow control valve switchable between cooling and heating modes, a gas reheat heat exchanger, a fan, and a secondary refrigerant flow control device switchable between first, second, and third modes. Refrigerant flows from the compressor discharge line to the main refrigerant flow control device in the first mode. Refrigerant flows from discharge line to gas reheat heat exchanger and then main refrigerant flow control valve in the second mode. Refrigerant flows both from discharge line to gas reheat heat exchanger and then main refrigerant flow control valve, and from discharge line to main refrigerant flow control valve without flowing through the gas reheat heat exchanger in the third mode. Refrigerant flows to the usage side and hot gas reheat heat exchanger in the heating mode.

A gas heat pump system including an outdoor unit having a compressor, an outdoor heat exchanger, and an expansion device; an indoor unit having an indoor heat exchanger; a refrigerant pipe to connect the outdoor unit and the indoor unit; an engine to combust mixed fuel in which fuel and air are mixed; a coolant tank to store a coolant; a radiator to emit, to an outside, heat which is transferred from the engine to the coolant; and a coolant pipe to connect the coolant tank and the radiator to allow the coolant to circulate therethrough, whereby the gas heat pump system has a cooling capability between 71 kW and 85 kW, the refrigerant is a mixed refrigerant having at least 50% R32, and the refrigerant pipe is a ductile stainless steel pipe having a delta ferrite matrix structure of 1% or less based on grain area.

An outdoor heat exchanger includes: a main heat exchange area; a sub heat exchange area; and a connecting pipe and a connecting pipe interconnecting the main heat exchange area and the sub heat exchange area. The main heat exchange area has a main heat exchange channel and a main heat exchange channel. The sub heat exchange area has a sub heat exchange channel, a sub heat exchange channel, and a sub heat exchange channel. The connecting pipe connects the sub heat exchange channel and the sub heat exchange channel to the main heat exchange channel while the sub heat exchange channels are joined together. The connecting pipe interconnects the sub heat exchange channel and the main heat exchange channel.

A refrigeration cycle apparatus includes a compressor, a four-way valve, a second flow path switching unit, a first outdoor heat exchanger, a second outdoor heat exchanger, a first indoor heat exchanger and a second flow path switching unit. The second flow path switching unit switches between a third state in which the first port, the second port, the first outdoor heat exchanger, the fourth port, the third port, the second heat exchanger, the fifth port and the sixth port are successively connected in series, and a fourth state in which the sixth port, the fourth port, the first heat exchanger, the second port and the first port are successively connected in series, and the sixth port, the fifth port, the second heat exchanger, the third port and the first port are successively connected in series.

A refrigeration cycle apparatus includes a compressor, an expansion valve, a flow switching device, a heat source side heat exchanger including a first heat source side heat exchanger and a second heat source side heat exchanger connected in parallel, an opening-and-closing valve provided on downstream of the second heat source side heat exchanger through which refrigerant flows during a defrosting operation, and a controller that, when the defrosting operation is performed, controls the flow switching device so that the refrigerant discharged from the compressor flows into the heat source side heat exchanger. The controller switches the opening-and-closing valve from an open state to a closed state when the defrosting operation is started, determines a point in time when defrosting targets to be defrosted are switched, and switches the opening-and-closing valve from the closed state to the open state in accordance with the point in time determined.