Numerical simulation on performance band of automotive air conditioning system with a variable displacement compressor

A mathematical model of an automotive air conditioning (AAC) system with a variable displacement compressor (VDC) is developed in order to simulate and analyze its steady-state performance. A test system is established to validate the system model, and the simulated results agree well with the experimental data. The simulation results show that there is a performance band for the system parameter relationship due to the frictional forces between the moving components of the VDC within which all the steady-state points fall. Different from the one–one parameter relationship in an AAC system with a fixed displacement compressor, it is a multiple–one parameter relationship in the AAC system with a VDC. The influence of the compressor rotary speed, air temperature at the condenser inlet and air flow rate through the evaporator on the performance band is simulated. The evaporating pressure performance band moves in the direction of increasing evaporator inlet air temperature and increasing evaporating pressure when the compressor rotary speed increases. The evaporating pressure performance band moves in the direction of decreasing evaporating inlet air temperature and decreasing evaporating pressure when air temperature at the condenser inlet or air flow rate through the evaporator increases.