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 and liquid return prevention control method thereof. When the multi-split air conditioning system is in heating operation, the multi-split air conditioning system is switched to a defrosting mode to operate for defrosting if an outdoor unit receives a defrosting instruction. After detecting gas exhaust pressure, gas return pressure and gas exhaust temperature of a compressor in real time, the multi-split air conditioning system sends a defrosting completion signal to a diverter, controls the compressor to reduce frequency and a plurality of electric-control valves to open, and controls any one of the electric-control valves to open and the rest of the electric-control valves to close during reversing of a four-way valve, so as to reduce the amount of a refrigerant returned to a low-pressure gas-liquid separator.

An air conditioning apparatus and a method for controlling an air conditioning apparatus are provided. The air conditioning apparatus may include a controller that performs an abnormal operation diagnosis of the air conditioning apparatus based on an output signal of a pump, thereby directly checking introduction of air into pipes or clogging of valves.

A heat pump may include a compressor configured to compress a refrigerant, a first temperature sensor provided in heating pipes connected to a heating device that heats an indoor space to sense a temperature of fluid flowing through the heating pipes, and a controller. The controller may be configured to determine whether a boiler is operating to heat an indoor space or is operating to supply hot water based on a sensing value of the first temperature sensor. The compressor may operate when the controller determines that the boiler is not operating to heat the indoor space and/or determines that the boiler is operating to supply hot water.

An air conditioning apparatus may include an outdoor unit through which a first fluid, such as refrigerant circulates, an indoor unit through which a second fluid, such as water circulates, a heat exchange device which is configured to connect the outdoor unit to the indoor unit and in which the first fluid and the second fluid are heat-exchanged with each other, first to third inner tubes configured to connect the outdoor unit to the heat exchange device, and a heat storage unit connected to the first to third inner tubes.

An air conditioning apparatus may include an outdoor unit through which a first fluid, such as refrigerant circulates, an indoor unit through which a second fluid, such as water circulates, a heat exchange device which is configured to connect the outdoor unit to the indoor unit and in which the first fluid and the second fluid are heat-exchanged with each other, a first inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid at high-pressure flows, a second inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid at low-pressure flows, and a third inner tube which is configured to connect the outdoor unit to the heat exchange device and through which the first fluid in liquid form flows. The heat exchange device may include a bypass tube configured to bypass the second inner tube and a flow control valve provided in the bypass tube.

An air conditioner includes an outdoor unit including a compressor for compressing a refrigerant and an outdoor heat exchanger for exchanging heat between the refrigerant and outside air. A ventilation device is connected to a plurality of refrigerant pipes, and configured to direct outside air into an indoor space, and indoor air to the outside. The ventilation device includes a case, a main heat exchanger, a recovery heat exchanger, and a refrigerant distributor. The refrigerant distributor is configured to direct the refrigerant between the main heat exchanger and the recovery heat exchanger.

An air conditioner includes an outdoor unit including a compressor for compressing a refrigerant and an outdoor heat exchanger for exchanging heat between the refrigerant and outside air. A ventilation device is connected to the outdoor unit through a liquid refrigerant pipe, a high-pressure refrigerant pipe, and a low-pressure refrigerant pipe. The ventilation device supplies the outside air to an indoor space, and discharges indoor air to the outside. The ventilation device includes a case, a main heat exchanger, a recovery heat exchanger, a refrigerant distributor, and a re-heat heat exchanger. A liquid refrigerant pipe valve is disposed in the liquid refrigerant pipe for controlling an amount of refrigerant.

A heat recovery variable-frequency multi-split heat pump system and a control method thereof. The system includes an outdoor unit and at least two indoor units. The system is a three-pipe heating recovery multi-split heat pump system designed on the basis of a four-way reversing valve, and one indoor unit thereof is provided with two electronic expansion valves and two heat exchangers so that any indoor unit in the system can operate independently under three working conditions of refrigeration, heating or heat recovery dehumidification. Under multi-split condition, the system can operate under six working conditions, namely, the full-refrigeration working condition, the full-heating working condition, the common-heat-recovery working condition, the common-heat-recovery-dehumidification working condition, the heat recovery dehumidification-refrigeration-combination working condition and the heat recovery dehumidification-heating-combination working condition. Under the heat recovery dehumidification condition, a lower outlet air temperature, during low-temperature dehumidification, is raised by means of heat removal of a condenser so as to achieve the purpose of dehumidification without temperature fall or temperature rise, so that the thermal comfort and efficiency of the system are improved, and the refrigerating capacity and heating capacity of the system are effectively improved.

In an air-conditioning system including a thermal storage heat exchanger, a refrigerant circuit is configured such that an indoor heat exchanger and a receiver communicate with the thermal storage heat exchanger when an operational mode of the refrigerant circuit is switched to a cooling operation in which the thermal storage heat exchanger serves as a radiator and the indoor heat exchanger serves as an evaporator.