An air-conditioning apparatus includes a main circuit in which a compressor, a flow switching device, an indoor heat exchanger, a pressure reducing device, and a plurality of parallel heat exchangers connected in parallel with each other are connected by pipes, a bypass pipe, a flow control device provided to the bypass pipe and configured to adjust a flow rate of refrigerant flowing through the bypass pipe, an evaporating pressure sensor configured to measure an evaporating pressure of the refrigerant, and a controller. The air-conditioning apparatus is configured to operate in a normal heating operation mode and a heating-defrosting operation mode. When an operation associated with the normal heating operation mode is switched to an operation associated with the heating-defrosting operation mode, the controller adjusts an opening degree of the flow control device using the evaporating pressure in the parallel heat exchanger and a driving frequency of the compressor.

A heat pump system includes a first unit; a second unit connected to a first flow path of the first unit; and a third unit connected to a second flow path of the first unit and connected to the second unit. The heat pump system can operate in a cooling and water heating mode and a heating and water heating mode, wherein, in the cooling and water heating mode, the heat pump system is configured to switch a switching assembly to a first position and connect the at least one first heat exchangers and the second heat exchanger in series; in the heating and water heating mode, the heat pump system is configured to switch the switching assembly to a second position and connect the second heat exchanger and the at least one third heat exchangers in parallel.

A multi-air conditioner for heating/cooling operation may include: at least one indoor unit which is installed in a room, and includes an indoor heat exchanger; an outdoor unit which is connected to the indoor unit through a refrigerant pipe, and includes an outdoor heat exchanger, a compressor, an outdoor expansion valve, and a four-way valve; at least one leakage blocking valve which is formed on the refrigerant pipe, and blocks a refrigerant flow in the refrigerant pipe when a refrigerant leak occurs from the refrigerant pipe in the room; and a buffer unit which is installed on the refrigerant pipe between the indoor unit and the outdoor unit, and collects refrigerant leaking from the refrigerant pipe. Accordingly, when the refrigerant leaks into the room, it is possible to minimize the amount of the leaking refrigerant by collecting the refrigerant in the buffer tank.

A multi-air conditioner for heating and cooling may include at least one indoor unit, an outdoor unit, and at least one leak shut-off valve. The at least one indoor unit is installed in an indoor space and includes an indoor heat exchanger and an indoor expansion valve. The outdoor unit is connected to the at least one indoor unit via a refrigerant pipeline and includes an outdoor heat exchanger, a compressor, an outdoor expansion valve, and a four-way valve. The outdoor unit may decrease a pressure of the refrigerant pipeline when a refrigerant leak occurs from the refrigerant pipeline. The at least one leak shut-off valve is provided on the refrigerant pipeline and blocks a flow of refrigerant in the refrigerant pipeline when a refrigerant leak from the refrigerant pipeline occurs in the indoor space.

An outdoor unit of the heat pump includes a compressor, an oil separator provided in a discharge path of the compressor, an outdoor-unit connecting pipe connecting an intake path of the compressor and an outdoor unit of an another heat pump for supplying a refrigerant to the outdoor unit of the another heat pump, an oil supply pipe extending from a predetermined position of the oil separator and connecting to the outdoor-unit connecting pipe, an on-off valve provided on the oil supply pipe, an expansion valve provided in a portion of the outdoor-unit connecting pipe between a connecting part connected to the intake path and a connecting part connected to the oil supply pipe, and a refrigerant filling port provided in a portion of the outdoor-unit connecting pipe between the connecting part and the expansion valve.

A packaged terminal air conditioner unit includes a main expansion device connected to an interior coil such that the main expansion device is operable to throttle a flow of refrigerant to both a first coil section and a second coil section of the interior coil. A secondary expansion device is connected in series between the main expansion device and the second coil section of the interior coil such that the secondary expansion device is operable to throttle a flow of refrigerant to the second coil section of the interior coil. A controller is in operative communication with the secondary expansion device such that the controller adjusts the secondary expansion device to a configuration between a fully open configuration and a fully closed configuration during operation of the compressor.

A refrigeration apparatus includes a compressor, a heat-source-side heat exchanger operable as a refrigerant evaporator or radiator, and a usage-side heat exchanger operable as a refrigerant evaporator or radiator. The heat-source-side heat exchanger is disposed inside a heat source unit having an exhaust port and an outdoor fan in an upper part, and an intake port in a side part. The heat-source-side heat exchanger includes first and second heat-source-side heat exchangers. Adjustable first and second heat-source-side flow rate adjusting valves are connected to liquid sides of the first and second heat-source-side heat exchangers, respectively. In a defrost operation in order to defrost the first and second heat-source-side heat exchangers, the opening degrees of the first and second heat-source-side flow rate adjusting valves are controlled so as to achieve a defrost flow rate ratio at which more refrigerant flows to the second heat-source-side heat exchanger than during an air-cooling operation.

A refrigeration cycle apparatus includes a plurality of outdoor units. Each of the plurality of outdoor units includes an outdoor heat exchanger, a compressor, and a sensor to detect the quantity of refrigeration oil in the outdoor unit. A controller has a first operation mode in which a part of the plurality of outdoor units is operated and another outdoor unit is stopped; and a second operation mode in which all of the plurality of outdoor units are operated. In the first operation mode, when the operating time of an operating outdoor unit exceeds a prescribed time and the quantity of refrigeration oil in the compressor of the operating outdoor unit is equal to or larger than a prescribed quantity, the controller stops the operating outdoor unit and makes a switch to bring a stopped outdoor unit of the plurality of outdoor units into operation.

Provided is a refrigeration apparatus in which a decrease in a temperature of an indoor heat exchanger can be suppressed as much as possible while depletion of refrigerator oil in a compressor is also suppressed. An air-conditioning apparatus configured from a parallel connection of a plurality of outdoor units to an indoor unit, wherein when a predetermined defrosting condition has been fulfilled, a controller includes at least one processor programmed to selectively execute a reverse-cycle defrost mode when a predetermined outflow condition pertaining to an outflow integrated quantity of refrigerator oil has also been fulfilled, and selectively execute an alternating defrost mode, in which the outdoor unit that is to be defrosted is changed in sequence, when the predetermined outflow condition has not been fulfilled.

A suction injection pipe and a subcooling heat exchanger are provided at a main refrigerant circuit in which a main refrigerant circulates. Further, a sub-refrigerant circuit that differs from the main refrigerant circuit and in which a sub-refrigerant circulates is provided. A controller performs control for switching between a cooling action of the subcooling heat-exchanger that cools the main refrigerant that is sent to a main use-side heat exchanger by using the suction injection pipe and the subcooling heat exchanger, and a cooling action of the sub-refrigerant-circuit that cools the main refrigerant that is sent to the main use-side heat exchanger by using the sub-refrigerant circuit.