An outdoor unit for a heat recovery VRF air conditioning system and a heat recovery VRF air conditioning system are provided. The outdoor unit comprises: a compressor, having an exhaust port and a gas return port; a reversing assembly, having a first valve port, a second valve port, a third valve port and a fourth valve port; an outdoor heat exchanger, having a first end connected to the first valve port, and a second end connected to the second connector; 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; and a gas-liquid separator.

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.

A controller is configured to decide whether liquid refrigerant is unevenly distributed among a plurality of outdoor units and then adjust an outlet subcooling degree of an outdoor heat exchanger or an outlet sub cooling degree at a high-pressure outlet of a high-low pressure heat exchanger, and a discharge superheating degree of a compressor in a low capacity-side outdoor unit to match lower heat exchange capacity of the outdoor heat exchanger in the low capacity-side outdoor unit with higher heat exchange capacity of an outdoor heat exchanger in a high capacity-side outdoor unit, the low capacity-side outdoor unit being one of the plurality of outdoor units in which the outdoor heat exchanger has the lower heat exchange capacity, the high capacity-side outdoor unit being another of the plurality of outdoor units in which the outdoor heat exchanger has the higher heat exchange capacity.

A multi-split system and a liquid return prevention control method thereof during defrosting of the multi-split system. The method includes the following steps: when the multi-split system is in heating operation, detecting gas exhaust pressure (PC), gas return pressure (PE) and gas exhaust temperature (TP) of a compressor in real time; if an outdoor unit receives a defrosting instruction, sending a defrosting signal to a diverter and heating indoor units in multiple indoor units, controlling, by means of the diverter, a throttling element (EXV2) to close before first reversing of a four-way valve and last for a pre-set time, so as to reduce the amount of a refrigerant returned to the outdoor unit; and regulating the opening of the throttling element (EXV2) according to the gas exhaust pressure (PC), gas return pressure (PE) and gas exhaust temperature (TP) during defrosting operation of the multi-split system, so that the risk of liquid return occurred to the compressor during a defrosting process, and the safety and reliability of the system are greatly improved.

A multi-split air conditioning system having an outdoor unit and multiple indoor units and control method therefor. The control method comprises the following steps: obtaining an outdoor ambient temperature when an indoor unit sends a start instruction received from a user; determining whether the outdoor ambient temperature falls within a preset temperature range; and determining an operation mode of the multi-split system according to operations status of other existing started indoor units when the outdoor ambient temperature falls within the preset temperature range.

Provided is an air conditioner including at least one indoor unit; an EHP outdoor unit connected with the at least one indoor unit, and configured to control an applied current and drive an EHP compressor; a GHP outdoor unit connected with the at least one indoor unit and including a GHP compressor configured to operate using power from an engine driven through a combustion gas and an oil separator provided at an outlet side of the GHP compressor; an oil level sensor provided at the EHP outdoor unit or the GHP outdoor unit and configured to detect an amount of oil; and a control part configured to control an RPM of the EHP compressor or the GHP compressor based on information detected by the oil level sensor.

A refrigeration cycle apparatus includes a refrigeration cycle circuit which includes a plurality of load-side heat exchangers; a plurality of indoor units which accommodate the plurality of load-side heat exchangers, respectively; and a controller which controls the plurality of indoor units. Each of the plurality of indoor units includes an air-sending fan. At least one of the plurality of indoor units includes a refrigerant detection unit. The controller divides the plurality of indoor units into one or more groups. The controller is set such that when refrigerant is detected by the refrigerant detection unit included in any of the plurality of indoor units, the controller causes the air-sending fans included in all the indoor units which belong to a same group as the indoor unit which includes the refrigerant detection unit which detects the refrigerant to be operated.

An air-conditioning apparatus includes a heat medium circuit in which a compressor, a flow switching unit, a flow regulating unit, a gas header, a heat source-side heat exchanger, a distributor, an expansion unit, and a use-side heat exchanger are connected by a pipe, and during a defrosting operation to defrost the heat source-side heat exchanger, heat medium circulates, in order, the compressor, the flow switching unit, the gas header, the heat source-side heat exchanger, the distributor, the expansion unit, and the use-side heat exchanger. The heat source-side heat exchanger includes a first heat exchange unit, and a second heat exchange unit provided lower than the first heat exchange unit. The flow regulating unit is configured to, during the defrosting operation, regulate a flow rate of heat medium flowing through the first heat exchange unit and a flow rate of heat medium flowing through the second heat exchange unit.

An air conditioner includes a heat storage apparatus for storing heat emitted from a compressor arranged in an outdoor unit, wherein the heat storage apparatus includes a heat storage tank installed in the compressor for storing heat emitted from the compressor and a heat transfer member configured to deliver heat emitted from the compressor to the heat storage tank, wherein the heat storage tank includes a first heat transfer face configured to have a form corresponding to a part of an outer circumferential face of the compressor to come into contact with the outer circumferential face of the compressor and a pair of second heat transfer faces configured to extend from both ends of the first heat transfer face to be in parallel to each other and form space with the outer circumferential face of the compressor, and wherein the heat transfer member is arranged in the space.

An air conditioner is provided. The air conditioner may include a subcooling heat exchanger that evaporates a refrigerant, a compressor that compresses the refrigerant, an injection flow channel through which the evaporated refrigerant flows into the compressor, an injection valve that opens and closes the injection flow channel, an oil separator that separates oil from refrigerant discharged from the compressor, and an oil injection line, which communicates at a first end thereof with the oil separator and at a second end thereof with the injection flow channel so as to guide the oil separated by the oil separator toward the injection flow channel. The oil separated by the oil separator may selectively flow into the compressor through the oil injection line and the injection flow channel in accordance with a mode of operation of the air conditioner.