Investigation on the discharge port and discharge valve lift in the R32 rotary compressor for performance improvement

The performance of the rotary compressor is critical to the efficiency of air conditioning systems. Cooling capacity, input power and coefficient of performance (COP) are three key indicators used to evaluate the performance of rotary compressors. The discharge area, determined by the discharge port diameter and discharge valve plate (DVP) displacement, significantly influences these three indicators. This paper introduces a conical discharge port aimed at increasing the discharge port perimeter, along with an optimized design of DVP lift, which primarily affects DVP displacement. A mathematical model is developed to investigate the impact of the discharge port and DVP lift on the aforementioned performance indicators. Experimental validation is conducted to verify the calculated results and compare the performance of three compressor prototypes: basic prototype having a cylindrical discharge port and a 2.5 mm DVP lift; Prototype I having a conical discharge port and a 2.5 mm DVP lift; and Prototype II having a conical discharge port and a 2 mm DVP lift. The errors between the calculated and experimental values for cooling capacity, input power, and COP are within 3 %, 2 %, and 4 %, respectively, demonstrating the high accuracy of the developed mathematical model. Furthermore, the comparative analysis reveals that prototype II, equipped with a conical discharge port and a 2 mm DVP lift, exhibits superior performance among these three prototypes.