Comparative performance of an automotive air conditioning system using fixed and variable capacity compressors

This study investigates the experimental performance of an automotive air conditioning (AAC) system for the cases of employing fixed and variable capacity compressors (FCC and VCC). For this aim, an experimental system consisting of original components from an HFC134a AAC system has been set up and instrumented. For each compressor case, the system has been tested under steady-state operating conditions by varying the compressor speed, temperatures of the air streams entering the condenser and evaporator as well as the velocities of these air streams. The energy and exergy analysis has been applied to the experimental system, and its performance for both compressor operations has been evaluated. The results show that the operation with the VCC usually yields a higher COP than the operation with the FCC in expense of a lower cooling capacity. Furthermore, the cooling capacity and the rate of total exergy destruction in the VCC operations remain almost constant after a certain compressor speed, while both parameters increase continually with the compressor speed in the FCC operations.