Air conditioning system, vehicular air conditioning system and control method of vehicular air conditioning system

Abstract

An air conditioning system comprises a compressorwhich compresses a refrigerant made of carbon dioxide, a radiatorwhich radiates heat of the refrigerant compressed by the compressor, an expansion valvewhich decompresses the refrigerant which dissipated heat by the radiatorand which can control a refrigerant pressure on the outlet side of the radiator, an evaporatorwhich evaporates the refrigerant decompressed by the expansion valve, a sensorwhich detects temperatures of a surface of a pipe through which a high pressure refrigerant on the outlet side of the radiator passes, and a control apparatuswhich calculates a target refrigerant pressure on the outlet side of the radiatorbased on a value detected by the sensor to control the expansion valve. The control apparatus corrects the target refrigerant pressure on the outlet side of the radiatorcorresponding to refrigerant temperatures. With this configuration, even if the temperature of the pipe surface is different from the actual refrigerant temperature, the air conditioning system can be controlled under an appropriate target refrigerant pressure.