A refrigeration apparatus includes a heat source-side unit and a utilization-side unit that are connected to each other, and performs a refrigeration cycle in which a high pressure of a refrigerant reaches or exceeds a critical pressure. The refrigeration apparatus also includes a control unit configured to perform a first action of returning the refrigerant to the heat source-side unit when a stop condition of the utilization-side unit is satisfied, and a second action of prohibiting the first action when a pressure at the heat source-side unit is equal to or more than the critical pressure of the refrigerant. This configuration suppresses damage to a refrigerant storage reservoir and the like in returning the refrigerant to the heat source-side unit.

An air conditioner includes an outdoor unit including a compressor, first and second indoor heat exchangers to receive a refrigerant from the outdoor unit, the second indoor heat exchanger receiving the refrigerant independently of the first indoor heat exchanger, and a fan disposed between the first and second indoor heat exchangers. First and second refrigerant pipes form flow paths between the outdoor unit and the first and second indoor heat exchangers. First and second expansion valves are disposed on the first and second refrigerant pipes. Third and fourth refrigerant pipes form flow paths between the compressor and the first and second indoor heat exchangers. A first opening and closing valve selectively opens and closes a fifth refrigerant pipe to selectively allow refrigerant to flow between the second and third refrigerant pipes. Second and third opening and closing valves selectively open and close the second and third refrigerant pipes.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device connecting the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor devices and the heat exchanger.

An air conditioner may include a continuous refrigeration apparatus including a first gas control unit connected to a first indoor heat exchanger, a second gas control unit connected to a second indoor heat exchanger, a first pipe connecting a liquid pipe of an outdoor unit and a liquid of an indoor unit, and a second pipe branched from the first pipe and connected to the first and second gas control units. The first gas control unit may include a first-first flow path connecting the first gas control unit to the second pipe; a first-second flow path connected to the first-first flow path, and through which refrigerant discharged from the first indoor heat exchanger flows during a refrigeration operation; and a first-third flow path connected in parallel with the first-second flow path, and guiding refrigerant from the compressor to the first indoor heat exchanger during a defrosting operation.

A defrosting control method for a multi-split system is provided. A multi-split system comprises an outdoor unit and multiple indoor units. An expansion valve is provided on a connecting pipeline between each of the indoor units and the outdoor unit. When the expansion valve of each activated indoor unit is closed and the degree of opening of the expansion valve of each off-state indoor unit is less than or equal to a maximum set degree of opening, the system satisfies a defrosting requirement, and as a result the method controls the expansion valve of each activated indoor unit to remain closed, thereby resolving the issue of a dramatic temperature drop in a room having an activated indoor unit during defrosting and improving user satisfaction. The degree of opening of the expansion valve of a off-state indoor unit is Off_PLS, and is controlled such that Off_PLS=ALL_HP*Avg_PLS/Off_HP. The invention satisfies a defrosting requirement and reduces the degree of opening of the expansion valves as much as possible, thereby preventing damage to a compressor without affecting defrosting.

A refrigeration cycle apparatus includes a refrigeration circuit in which non-azeotropic refrigerant mixture circulates. The refrigeration circuit includes a compressor, an outdoor heat exchanger, an indoor heat exchanger, an expansion valve, and a four-way valve. The four-way valve is configured to assume a first state and a second state. The outdoor heat exchanger includes a plurality of refrigerant flow paths and a linear flow path switching valve configured to switch connections of the plurality of refrigerant flow paths between a series state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in series and a parallel state in which the non-azeotropic refrigerant mixture flows through the plurality of refrigerant flow paths in parallel. A controller switches the linear flow path switching valve between the series state and the parallel state when a multi-way valve is in the second state.

An air conditioning apparatus includes an outdoor device that is configured to circulate refrigerant and that includes a compressor and an outdoor heat exchanger, a plurality of indoor devices configured to circulate water, and a heat exchange device that connects the outdoor device with the indoor device. The heat exchange device includes a heat exchanger configured to exchange heat between the refrigerant and the water, and a switch device configured to control flow of refrigerant between the indoor device and the heat exchanger.

A thermo-hygrostat air conditioner is provided that may include at least one indoor unit installed indoors, and including a main coil that provides air that meets a predetermined humidity by dehumidifying outdoor air and a sub coil that cools or heats the dehumidified air at a predetermined temperature and provides the air indoors; and an outdoor unit connected to the main coil and the sub coil of the indoor unit via a refrigerant pipe and including at least one outdoor heat exchanger, at least one compressor, at least one outdoor expansion valve and at least one four way valve. A mode of the main coil and the sub coil may be determined depending on a cooling load and a heating load. The outdoor unit may control the four way valve according to the mode of the main coil and the sub coil and provide refrigerant to the main coil and the sub coil according to the mode.

There is provided an air conditioner capable of displaying sufficient cooling ability in each indoor unit by allowing a sufficient amount of refrigerant to flow into indoor units where cooling ability cannot be displayed. By executing refrigerant amount balance control, since degrees of opening of indoor expansion valves are narrowed in indoor units whose refrigerant superheating degrees are smaller than an average refrigerant superheating degree, amounts of refrigerant flowing into the indoor expansion valves are decreased. In the indoor unit where the refrigerant superheating degree is higher than the average refrigerant superheating degree, since refrigerant pressure on a downstream side of the indoor expansion valve is also decreased due to the degrees of opening of the indoor expansion valves being narrowed, the difference in pressure between the upstream side and the downstream side of the indoor expansion valve increases and an amount of refrigerant flowing into the indoor unit is increased.

Provided is an air conditioning apparatus. The air conditioning apparatus includes an outdoor unit which includes a compressor and an outdoor heat exchanger and through which a refrigerant is circulated, an indoor unit through which water is circulated, a heat exchanger in which the refrigerant and the water are heat-exchanged with each other, a water tube configured to guide the water circulated through the indoor unit and the heat exchanger, a pump installed in the water tube, and a controller configured to analyze an output signal of the pump so as to calculate a ration of an air layer in the water tube, the controller being configured to control a target supercooling degree or target superheating degree of the heat exchanger according to the calculated ratio of the air layer.