An air-conditioning apparatus includes a compressor and an outdoor heat exchanger that operates as an evaporator. A first heat exchange unit of the outdoor heat exchanger includes: first heat transfer tubes extending in an upward/downward direction, and arranged apart from each other in a lateral direction; a first junction pipe extending in the lateral direction, and connected to the lower ends of the first heat transfer tubes; an outflow pipe connected to the first junction pipe at or below a center position of the first junction pipe in the upward/downward direction; second heat transfer tubes extending in the upward/downward direction, and arranged apart from each other in the lateral direction; a first distribution pipe extending in the lateral direction, and connected to the lower ends of the second heat transfer tubes, and a first connection part connecting upper ends of the first heat transfer tubes and upper ends of the second heat transfer tubes.

An air conditioner that includes a compressor that compresses a refrigerant, a main outdoor heat exchanger that condenses the refrigerant in a cooling mode and that evaporates the refrigerant in a heating mode, an indoor heat exchanger that evaporates the refrigerant in the cooling mode while condensing the refrigerant in the heating mode, a switch that guides the refrigerant discharged from the compressor to the main outdoor heat exchanger in the cooling mode and that guides the refrigerant discharged from the compressor to the indoor heat exchanger in the heating mode, and a sub outdoor heat exchanger that evaporates a portion of the refrigerant condensed in the main outdoor heat exchanger in a low-load cooling mode and that condenses a portion of the refrigerant discharged from the compressor in a low-load heating mode.

An air-conditioning apparatus includes: a compressor allowing refrigerant injection thereto and compress and discharge the refrigerant at a high temperature; an indoor heat exchanger exchanging heat between air and refrigerant; a first flow rate control device adjusting and controlling a flow rate of refrigerant; and a plurality of outdoor heat exchangers being in parallel to exchange heat between outside air and refrigerant, a first defrosting pipe allowing a branched part of the refrigerant discharged from the compressor to pass and flow into the outdoor heat exchanger to be defrosted; a reducing device adjusting a pressure of refrigerant passing through the first defrosting pipe to a medium pressure; a second defrosting pipe from which the refrigerant having passed through the outdoor heat exchanger to be defrosted is injected into the compressor; and a reducing device adjusting a pressure of refrigerant passing through the second defrosting pipe to an injection pressure.

A system comprising a compressor, a first valve coupled to the compressor and coupled to a first coil, a first expansion valve coupled to the first coil, a second coil, and a second expansion valve. The second expansion valve coupled to a third coil, a second valve coupled to the compressor and the third coil. A controller operable to operate the first valve, the first expansion valve, the second expansion valve, and the second valve. The second coil is coupled to the compressor and the refrigerant flows from the second coil to the compressor.

An air-conditioning apparatus includes two heat source units, each including a compressor, an outdoor heat exchanger functioning as an evaporator, an accumulator connected to a suction side of the compressor, and at least one of an outdoor air-sending device configured to supply air corresponding to a heat exchange target for refrigerant to the outdoor heat exchanger or a flow control device (bypass and expansion device for bypass) configured to regulate a flow rate of the refrigerant flowing through the outdoor heat exchanger. A controller is configured to control at least one of the outdoor air-sending device or the flow control device so that a suction quality of the compressor of an upper heat source unit installed on an upper side and a suction quality of the compressor of a lower heat source unit installed on a lower side become the same.

In an air conditioning apparatus, when the amounts of refrigerant oils retained in a first compressor and a second compressor are increased and oil levels in the first compressor and the second compressor reach a first oil outflow part and a second oil outflow part, the refrigerant oils subsequently sucked into the first compressor and the second compressor flow out of the first oil outflow part and the second oil outflow part to a first oil outflow pipe and a second oil outflow pipe, and flow from the first oil outflow pipe and the second oil outflow pipe to a refrigerant outflow pipe. The refrigerant oils flowing in the refrigerant outflow pipe from the first and second compressor through the first and second oil outflow pipe flow out of an outdoor unit through a four-way valve, and circulate through a refrigerant circuit together with refrigerants.

An air conditioner system including a compressor, a condenser, an expander, an evaporator, and a bypass pipeline that guides the evaporated refrigerant from the evaporator to the condenser, wherein the bypass pipeline includes: a first bypass pipe configured to guide at least some of the evaporated refrigerant from the evaporator to the condenser; a second bypass pipe attached to the first bypass pipe to allow heat exchange between refrigerant in the condenser and refrigerant therein; and a third bypass pipe coupled to the second bypass pipe to guide the refrigerant from the second bypass pipe out of the condenser.

Embodiments as disclosed herein are directed to a heat pump that employs at least two different refrigerants, each of which is optimized for either a cooling operation mode or a heating operation mode. The embodiments as disclosed herein can help increase the capacity and/or efficiency of a heat pump in both the cooling operation mode and the heating operation mode. In addition, the embodiments as disclosed herein may also eliminate the need for a ground source in a relatively low ambient temperature environment.

Provided are an air conditioner and a method of controlling the same. The air conditioner includes an indoor unit including an indoor heat exchanger, a first outdoor unit connected to the indoor unit, the first outdoor unit including a first compressor compressing a refrigerant and a first outdoor heat exchanger, a second outdoor unit including an engine generating a power by using combustion gas, a generator supplying electricity into the first compressor by using the power generated in the engine, a second compressor compressing the refrigerant by using the power of the engine, and a second outdoor heat exchanger, and a controller determining an additional operation of the second compressor on the basis of required cooling or heating load while the first compressor operates.

Disclosed are a method and a device for controlling refrigerant in an air conditioning system. The method includes: S1: comparing a superheat degree of each outdoor unit with an average superheat degree; S2: if the superheat degree of a present outdoor unit is higher than the average superheat degree, and a first different between the superheat degree of the present outdoor unit and the average superheat degree is greater than a present value, increasing a refrigerant amount entered into the present outdoor unit; and S3: if the superheat degree of the present outdoor unit is lower than the average superheat degree, and a second different between the average superheat degree and the superheat degree of the present outdoor unit is greater than the present value, decreasing the refrigerant amount entered into the present outdoor unit. Therefore, the refrigerant amount entered into each outdoor unit is adjusted from systemic overall perspective.