EXPERIMENTAL PERFORMANCE OF AN AUTOMOBILE AIR CONDITIONING SYSTEM USING AN ORIFICE TUBE FOR FIXED AND VARIABLE CAPACITY COMPRESSORS

This study investigates the experimental performance of an automotive air conditioning (aac) system using an orifice tube as an expansion device for fixed and variable capacity compressors (fcc and vcc). an experimental aac system using r134a as refrigerant has been set up in the laboratory, and instrumented. the system has been operated with fcc and vcc, and tested by varying the compressor speed as well as the temperatures of the air streams entering the condenser and evaporator. by applying energy analysis to the experimental system, its performance parameters have been evaluated for both compressor cases, and presented in comparative graphics. the experimental results show that the cooling capacity and the exergy destruction in the system usually increase with the compressor speed, while the coefficient of performance (cop) decreases with it. the cooling capacity and cop get higher on increasing the temperature of the air stream entering the evaporator or decreasing the temperature of the air stream entering the condenser. it is revealed that using the fcc yields 5─10% higher cooling capacity compared to the case of using the vcc, and causes higher cop values at low speeds. however, as a result of the intervention of the capacity control system, using the vcc yields higher cop values at high speeds.