Evaluation of the impacts of refrigerant charge on air conditioner and heat pump performance

Abstract

The paper provides results that show the impact of charge level on capacity and efficiency for several units tested in the laboratory. To evaluate the performance, capacity ratio and COP ratio were determined from measurements at various refrigerant charge levels and operating conditions. For all systems considered in this study, a refrigerant charge reduction of 25% led to an average energy efficiency reduction of about 15% and capacity degradation of about 20%. To evaluate the economic value of charge detection and correction, Seasonal Energy Efficiency Ratio (SEER) and annual cost of electricity were determined for some case studies based on the tested units. The results imply that charging inaccuracies could cause significant decreases in SEER, leading to increases in the operating costs. When the refrigerant was charged to 75% of design, the SEER value decreased by 16% and annual operating cost was increased by US$ 100 per ton of capacity.