Air conditioning apparatus, heat exchanger for use in the apparatus and apparatus control method

An air conditioning apparatus comprising a compressor of variable displacement type;

• a condenser connected to the discharge side of said compressor, said condenser being comprised of a pair of headers disposed parallel to each other and having refrigerant passages formed therein, a plurality of heat transfer pipes arranged between said headers to form refrigerant passages, a number of fins disposed in respective air passage spaces between adjacent pairs of said heat transfer pipes, and a refrigerant flow rate control valve for opening and closing the refrigerant passage in at least one of said headers;
• an expansion valve connected to the outlet side of said condenser;
• an evaporator connected between the outlet side of said expansion valve and the suction side of said compressor;
• control means for controlling an opening and closing operation of said refrigerant flow rate control valve;
• and a temperature sensor for detecting an atmospheric temperature, wherein said refrigerant flow rate control valve is controlled by said control means to be opened and closed for reducing the effective heat transfer area of said condenser, when the atmospheric temperature detected by said temperature sensor is determined to be low.

A control method for an air conditioning apparatus comprising a compressor;

• a condenser connected to the discharge side of said compressor, said condenser being comprised of a pair of headers disposed parallel to each other and having refrigerant passages formed therein, a plurality of heat transfer pipes arranged between said headers to form refrigerant passages, a number of fins disposed in respective air passage spaces between adjacent pairs of said heat transfer pipes, and a refrigerant flow rate control valve for opening and closing the refrigerant passage in at least one of said headers;
• an expansion valve connected to the outlet side of said condenser;
• an evaporator connected between the outlet side of said expansion valve and the suction side of said compressor;
• control means for controlling an opening and closing operation of said refrigerant flow rate control valve;
• and sensor means for detecting a refrigerant pressure or temperature on the outlet side of said condenser, wherein said refrigerant flow rate control valve is controlled by said control means to be opened and closed dependent on a signal value for changing the effective heat transfer area of said condenser.