Enhanced-vapor-injection air conditioning system and control method thereof

The invention discloses a kind of air injection enthalpy-increasing air-conditioning system and its control method, wherein, the air injection enthalpy-increasing air-conditioning system includes increasing enthalpy pipeline, and main refrigerant pipeline and the main refrigerant pipeline loop for connecting indoor apparatus of air conditioner and air-conditioner outdoor unit；The increasing enthalpy line entry end connects the arbitrary node of the main refrigerant pipeline, the increasing enthalpy tube outlet end connects the air injection enthalpy-increasing mouthful of the main compressor, supplementary heat exchanger and auxiliary compressor are provided between the increasing enthalpy line entry end and the increasing enthalpy tube outlet end, enter the auxiliary compressor gas returning port after into the heat of vaporization in the refrigerant absorption supplementary heat exchanger of the increasing enthalpy pipeline into gaseous coolant, the auxiliary compressor exhaust outlet is connected with the increasing enthalpy tube outlet end.In technical scheme proposed by the present invention, in the presence of auxiliary compressor, the enthalpy for adding to gaseous coolant in main compressor is higher, and the air injection enthalpy-increasing than general air injection enthalpy-increasing air-conditioning system is in hgher efficiency.