An outdoor unit of an air conditioner coupled to an indoor unit by a liquid pipe and a gas pipe, includes: a compressor; an outdoor heat exchanger; a discharge pipe coupled to a refrigerant discharge side of the compressor; an intake pipe coupled to a refrigerant intake side of the compressor; an outdoor-unit high-pressure gas pipe coupled to the discharge pipe; an outdoor-unit low-pressure gas pipe coupled to the intake pipe; an outdoor-unit liquid pipe that couples a first refrigerant entry/exit opening of the outdoor heat exchanger and the liquid pipe together; a bypass pipe coupled to the outdoor-unit liquid pipe; a first flow-passage switcher coupled to a second refrigerant entry/exit opening of the outdoor heat exchanger, the discharge pipe, the intake pipe, and the bypass pipe; and a second flow-passage switcher coupled to the gas pipe, the outdoor-unit high-pressure gas pipe, and the outdoor-unit low-pressure gas pipe.

An air conditioner includes an indoor unit, an outdoor unit, and a controller. The outdoor unit is connected to the indoor unit, and the outdoor unit includes a housing, a compressor, a four-way valve, an outdoor fan, a separating device, and a plurality of outdoor heat exchangers arranged in parallel. The controller is coupled to the compressor, the four-way valve, the outdoor fan, and the driving assembly, and is configured to control a first portion of a refrigerant flowing out from the compressor to flow into an outdoor heat exchanger; control a second portion of the refrigerant flowing out from the compressor to flow into the indoor unit; and when a time in which the first portion of the refrigerant flows into the outdoor heat exchanger is less than a first preset time, prevent a refrigerant flowing out from the indoor unit from flowing into the outdoor heat exchanger, and control the driving assembly to drive the wind blocking portion to move, so as to separate the outdoor fan from the outdoor heat exchanger.

An air conditioner of an embodiment includes a plurality of outdoor units, one or more indoor units, and a control unit. The outdoor unit includes a compressor, a four-way valve, an outdoor heat exchanger, an outdoor expansion valve and an outdoor blower, and the outdoor units exchange heat between the outside air and a refrigerant. The indoor unit is an indoor unit connected to the plurality of outdoor units by a refrigerant pipe, includes an indoor heat exchanger, an indoor expansion valve, and an indoor blower, and exchanges heat between the indoor air and the refrigerant. The control unit controls the plurality of outdoor units and the one or more indoor units. The control unit controls the condensation pressure of the outdoor unit in a heating operation or the suction pressure of the outdoor unit in a defrosting operation to be equal to or smaller than an upper limit pressure, which is 1/1.5 times the rated maximum pressure during the heating operation when any of the outdoor units is in the defrosting operation.

An air-conditioning apparatus includes a refrigerant circuit and a controller. The refrigerant circuit includes a main circuit and a bypass circuit. The bypass circuit is connected, by a pipe, to each of a plurality of parallel outdoor heat exchangers via a defrosting refrigerant pressure-reducing device, a defrosting flow passage switching device, and a backflow prevention device. The controller switches a flow passage for use in introduction of refrigerant using the defrosting flow passage switching device, to select one of the plurality of parallel outdoor heat exchangers as a defrosting target to be defrosted; and supplies defrosting refrigerant whose pressure is reduced by the defrosting refrigerant pressure-reducing device to the selected one of the plurality of parallel outdoor heat exchangers.

A heating, ventilation, and/or air conditioning (HVAC) system has a first variable refrigerant flow outdoor unit, a first ducted variable speed indoor unit configured to selectively exchange refrigerant with the first variable refrigerant flow outdoor unit, and a second indoor unit configured to selectively exchange refrigerant with the first variable refrigerant flow outdoor unit.

In a refrigeration apparatus, in a first operation mode, a comparison is made between a first liquid pipe temperature, which is a temperature of a refrigerant on a side of a liquid pipe heat exchanger that is near usage-side heat exchangers, and a second liquid pipe temperature, which is a temperature of the refrigerant on a side of the liquid pipe heat exchanger that is near a plurality of heat-source-side heat exchangers, the liquid pipe heat exchanger performing heat exchange with the refrigerant flowing through liquid sides of the heat-source-side heat exchangers. When an evaporation-switch liquid pipe temperature condition is satisfied, the heat-source-side heat exchanger functioning as a radiator of the refrigerant is switched to an evaporator of the refrigerant, and the first operation mode is switched to a second operation mode in which the plurality of heat-source-side heat exchangers are caused to function as evaporators of the refrigerant.

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.

An outdoor unit (100) for a heat recovery VRF air conditioning system and a heat recovery VRF air conditioning system are provided. The outdoor unit (100) comprises: a compressor (2), having an exhaust port (a) and a gas return port (b); a reversing assembly (3), having a first valve port (c), a second valve port (d), a third valve port (e) and a fourth valve port (f); an outdoor heat exchanger (4), having a first end connected to the first valve port (f), and a second end connected to the second connector (12); a plurality of one-way valves, wherein each one-way valve has a circulation end and a stop end, and each one-way valve is opened only in one direction from the circulation end to the stop end; a throttling element (6); and a gas-liquid separator (9).

A refrigeration apparatus includes a refrigerant circuit connecting heat-source units in parallel with usage units. First and second heat-source units have first and second compressors, first and second heat-source-side heat exchangers, first and second high-pressure receivers, first and second detecting elements detecting whether the receivers are near flooding, first and second bypass channels returning refrigerant in top parts of the receivers to intake sides of the compressors, and first and second motor-operated valves on the bypass channels, respectively. A controller performs excess refrigerant distribution control in which an opening degree of the first valve is controlled to be greater than an opening degree of the second valve when the second detecting element detects a nearly flooded state, and the opening degree of the second valve is controlled to be greater than the opening degree of the first valve when the first detecting element detects a nearly flooded state.

A heat exchange apparatus includes a first heat exchanger configured to transfer heat between a refrigerant and another medium, a plurality of second heat exchangers configured to transfer heat between the refrigerant and the liquid, a compressor configured to pressurize the refrigerant and a plurality of expansion devices for each of the plurality of second heat exchangers and configured to expand the refrigerant pressurized by the compressor, wherein the refrigerant flows through the plurality of second heat exchangers in parallel, and the liquid flows through the plurality of second heat exchangers in series.