An air conditioner includes an outdoor heat exchanger in which N heat exchange units are spaced apart from one another sequentially in a vertical direction N expansion valves respectively connected to the N heat exchange units; N hot gas pipes respectively connected to the N heat exchange units; N hot gas valves respectively installed in the N hot gas pipes; and a controller configured to control the N expansion valves and the N hot gas valves to defrost the N heat exchange units, wherein the controller is configured to defrost a bottom heat exchange unit first, then defrost a top heat exchange unit, and defrost the heat exchange units located under the top heat exchange unit sequentially from a second highest heat exchange unit to the bottom heat exchange unit after defrosting the top heat exchange unit.

A refrigeration cycle apparatus includes a refrigerant circuit which allows refrigerant to circulate therethrough, and an outdoor heat exchanger which exchanges heat between the refrigerant and outdoor air. The outdoor heat exchanger has first to third heat exchange sections. The second heat exchange section is located below the first heat exchange section, and the third heat exchange section is located below the second heat exchange section. In a refrigerant passage connecting the second and third heat exchange sections, a first pressure reducing device reduces a pressure of the refrigerant flowing through the refrigerant passage. In an operation mode in which the first and second heat exchange sections each serve as an evaporator, the third heat exchange section is located upstream of the second heat exchange section in the flow of the refrigerant, and refrigerant having a temperature higher than that of the outdoor air flows through the third heat exchange section.

A device for heating by absorbing latent heat of solidification of water, including a compressor (1), a condenser (2) and multiple evaporators (E1, E2) connected in parallel, each evaporator (E1, E2) has an electronic expansion valve (D1, D2) at its inlet, a solenoid valve (V1, V2) at its outlet; after the evaporators (E1, E2) are connected in parallel, outlets of the evaporators (E1, E2) are connected to an inlet of the compressor (1) and inlets of the evaporators (E1, E2) are connected to an outlet of the condenser (2); an outlet of the compressor (1) is connected to an inlet of the condenser (2); the compressor (1), the condenser (2) and the multiple parallel evaporators (E1, E2) form a closed loop system through pipelines; there are circulating refrigerants in the closed loop system, and heating and deicing processes are realized through a circulation of refrigerants; the solenoid valves (V1, V2) at the outlets of the evaporators (E1, E2) are switched between opening or closing to realize switching between evaporating and deicing functions of the evaporators (E1, E2).

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.

An air-conditioning apparatus is capable of performing a heating-defrosting operation where a specific one of a plurality of parallel heat exchangers is a heat exchanger to be defrosted and serves as a condenser while at least one parallel heat exchanger other than the heat exchanger to be defrosted serves as an evaporator. The air-conditioning apparatus includes a liquid refrigerant transporting unit for transferring liquid refrigerant from an accumulator to the heat exchanger to be defrosted. To perform the heating-defrosting operation, the air-conditioning apparatus supplies, to the heat exchanger to be defrosted, the liquid refrigerant transferred by the liquid refrigerant transporting unit.

An air conditioning apparatus includes a flow path switching valve. An outdoor heat exchanger is divided into a first heat exchanger and a second heat exchanger. During heating operation, a refrigerant is diverted and supplied to the first heat exchanger and the second heat exchanger. During the heating operation, the flow path switching valve combines the flows of the refrigerants discharged from the first heat exchanger and the second heat exchanger, and returns the resultant refrigerant to a refrigerant inlet of a compressor. Three ports of the flow path switching valve are internally communicated with one another while being isolated from an other single port during the heating operation. Two ports of the flow path switching valve are internally communicated with each other and other two ports are internally communicated with each other during defrosting operation of the first heat exchanger or the second heat exchanger.

Provided is a refrigeration apparatus in which adverse events caused by excess refrigerant can be suppressed even when defrosting is performed with some of a plurality of outdoor units designated as units to be defrosted. An air-conditioning apparatus is configured from a parallel connection of a first outdoor unit and a second outdoor unit, wherein when a second outdoor heat exchanger of the second outdoor unit is caused to function as an evaporator while a first outdoor heat exchanger of the first outdoor unit is caused to function as a condenser to defrost the first outdoor heat exchanger, a refrigerant circuit has a flow channel that supplies some of the refrigerant flowing out of the first outdoor heat exchanger to the second outdoor heat exchanger and a flow channel that supplies the rest of the refrigerant flowing out of the first outdoor heat exchanger to an indoor heat exchanger.

A heat pump system for conditioning regeneration air from a space is provided. The heat pump system is operable in a winter mode and/or a summer mode, and may be selectively operated in a defrost mode or cycle. During a defrost mode, hot refrigerant may be used to directly and sequentially defrost the regeneration air heat exchanger. A compressor may be configured to be overdriven during a defrost cycle.

An air conditioner includes a switching valve, a flow rate restricting portion and an on-off valve. The switching valve provided in a flow path between a compressor and an outdoor heat exchanger. The outdoor heat exchanger includes a heat exchange portion and a heat exchange portion. During heating operation, the switching valve causes a second connection port, a third connection port and a first connection port to communicate with one another. The flow rate restricting portion and the on-off valve are connected in series between an outlet and an inlet of the compressor during the heating operation, to bypass a part of refrigerant. During defrosting operation of the heat exchange portion, the switching valve is configured such that a fourth connection port and the second connection port communicate with each other, and the third connection port and the first connection port communicate with each other.

An air-conditioning apparatus includes a refrigerant circuit, an air-conditioning load state detection unit, an operation-state detection unit, and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The air-conditioning apparatus has a simultaneous heating and defrosting operation mode. In the simultaneous heating and defrosting operation mode, the controller controls a compressor, a pressure reducing device, and a defrosting refrigerant pressure-reducing device such that control amounts of the compressor, the pressure reducing device, and the defrosting refrigerant pressure-reducing device reach respective normal-time control target values that are set based on an air-conditioning load state and an operation state.