A refrigeration cycle apparatus includes a primary-side refrigerant circuit in which a first refrigerant circulates and a secondary-side refrigerant circuit in which a second refrigerant circulates. The primary-side refrigerant circuit includes a primary-side compressor, a primary-side flow path of a cascade heat exchanger, a primary-side heat exchanger, and a primary-side switching mechanism. The secondary-side refrigerant circuit includes a secondary-side compressor, a secondary-side flow path of the cascade heat exchanger, a secondary-side switching mechanism, a suction flow path, a plurality of utilization-side heat exchangers, a first connection flow path, connecting the plurality of utilization-side heat exchangers and the secondary-side switching mechanism, including a secondary-side first connection pipe, a first heat source pipe, first branch pipes, junction pipes, first connection pipes, and first utilization pipes, a second connection flow path, connecting the plurality of utilization-side heat exchangers and the suction flow path, including a secondary side second connection pipe, a second heat source pipe, second branch pipes, the junction pipes, the first connection pipes, and the first utilization pipes, a third connection flow path, connecting the plurality of utilization-side heat exchangers and the secondary-side flow path of the cascade heat exchanger, including a secondary-side third connection pipe, a fourth heat source pipe, a fifth heat source pipe, third branch pipes, second connection pipes, and second utilization pipes.

The refrigeration cycle apparatus includes a refrigerant circuit, a controller to control the refrigerant circuit, a bypass flow path, and a flow control valve. The bypass flow path communicates between the discharge side of the compressor and the first outdoor heat exchanger or between the discharge side of the compressor and the second outdoor heat exchanger. The flow control valve is provided to the bypass flow path. The refrigerant circuit is configured to be able to perform a heating defrosting simultaneous operation. The heating defrosting simultaneous operation is an operation of supplying part of the refrigerant discharged from the compressor to one of the first outdoor heat exchanger and the second outdoor heat exchanger via the bypass flow path, causing the other of the first outdoor heat exchanger and the second outdoor heat exchanger to serve as an evaporator, and causing the indoor heat exchanger to serve as a condenser.

Provided is an air conditioning apparatus that sufficiently raises the temperature of hot air to be blown out when receiving a request for high-temperature air temporarily raising the temperature of the hot air. A first use side unit includes a first use side heat exchanger and a first use side fan. A second use side unit includes a second use side heat exchanger and a second use side fan. When the first use side unit receives a request for the high-temperature air and the second use side unit receives no request for the high-temperature air, the air conditioning apparatus shifts to a mode that performs control to reduce the airflow volume of the second use side fan or make the airflow volume of the second use side fan zero such as reducing the number of revolutions of the second use side fan in another room by 40 rpm.

An air conditioner and a method for controlling an air conditioner. The method may include detecting an outlet temperature of a compressor; detecting a change in temperature of a hot water supply pipe; determining a system error based on the outlet temperature of the compressor; and determining an abnormality in an adjustment valve based on the temperature of the hot water supply pipe when a system error is determined.

A refrigeration system includes a compressor for compressing a gaseous refrigerant, such that the temperature and pressure thereof increases, whereas the boiling point thereof decreases; 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. The low temperature gaseous refrigerant entering the suction gas heat exchanger contains a certain amount of low temperature liquid refrigerant, said low temperature liquid refrigerant vaporizing as a result of the heat exchange with the high temperature liquid refrigerant from the condenser. Disclosed is also a refrigeration method.

A reversible refrigeration system including a compressor arranged to compress gaseous refrigerant, a four-way valve switchable between a heating position in which a payload is heated and a cooling position in which the payload is cooled. A payload heat exchanger is connected to the payload requiring heating or cooling, and a dump heat exchanger, two one-way valves, and two controllable expansion valves as well, wherein the one-way valves each are connected parallel to a corresponding expansion valve, wherein switching of the four-way valve between the heating position and the cooling position controls a flow of pressurized refrigerant to either of the payload heat exchanger or the dump heat exchanger and wherein the heat exchanger which receives the flow of pressurized refrigerant functions as a condenser and the other heat exchanger functions as an evaporator.

A reversible refrigeration system including a compressor arranged to compress gaseous refrigerant, a four-way valve switchable between a heating position in which a payload is heated and a cooling position in which the payload is cooled. A payload heat exchanger is connected to the payload requiring heating or cooling, and a dump heat exchanger, two one-way valves, and two controllable expansion valves as well, wherein the one-way valves each are connected parallel to a corresponding expansion valve, wherein switching of the four-way valve between the heating position and the cooling position controls a flow of pressurized refrigerant to either of the payload heat exchanger or the dump heat exchanger and wherein the heat exchanger which receives the flow of pressurized refrigerant functions as a condenser and the other heat exchanger functions as an evaporator.

Upon detection of a leakage of refrigerant, a refrigerant recovery operation is performed for operating a compressor in a state where an outdoor expansion valve is closed. The refrigerant suctioned from an indoor unit passes through an outdoor heat exchanger so as to be liquefied and accumulated in an outdoor unit. When a low-pressure detection value by a pressure sensor decreases below a reference value, a termination condition for the refrigerant recovery operation is satisfied, and the compressor is stopped. Furthermore, when an abnormality in the refrigerant recovery operation is detected based on a behavior of the low-pressure detection value obtained until the termination condition is satisfied, the compressor is stopped to thereby end the refrigerant recovery operation. Also, guidance information for notification about an abnormality is output to a user.

When a controller receives an instruction for a heating operation, the controller switches an operation mode of a refrigeration cycle apparatus between a heating operation mode and an oil recovery operation mode. The heating operation mode is a mode to circulate refrigerant in a refrigerant circuit such that the refrigerant flows through a gas extension pipe in a gas phase state. The oil recovery operation mode is a mode to circulate the refrigerant in the refrigerant circuit such that the refrigerant flows in the gas extension pipe in a gas-liquid two-phase state. The direction in which the refrigerant flows in the gas extension pipe in the oil recovery operation mode is opposite to that in which the refrigerant flows in the gas extension pipe in the heating operation mode.

An air conditioner including a refrigerant circuit including a compressor, an outdoor heat exchanger, an outdoor expansion valve, an indoor expansion valve, and an indoor heat exchanger. The refrigerant circuit including an auxiliary heat exchanger provided on a refrigerant pipe between the outdoor heat exchanger and the indoor expansion valve and connected in series with the outdoor expansion valve, and a rectifier configured to allow a refrigerant flowing from the outdoor heat exchanger toward the indoor expansion valve in a cooling operation or a refrigerant flowing from the indoor expansion valve toward the outdoor heat exchanger in a heating operation to sequentially flow through the auxiliary heat exchanger and the outdoor expansion valve.