Design and Performance Evaluation of a Cooler Refrigerating System Working with ‎Ozone Friendly Refrigerant

Abstract

In this study, a cooler refrigerating system was designed, constructed and tested with ‎various charge quantities of an ozone friendly hydro-fluorocarbon refrigerant (R134a) as ‎working fluid. The results obtained showed that the design temperature and pull-down time ‎set by International Standard Organisation (ISO) for small refrigerator were early achieved ‎with refrigerant charges of 100 and 120 g than with 60 and 80 g charges. Approximately the ‎same pull-down time and minimum temperature of -14oC were obtained with refrigerant ‎charges of 100 and 120 g. Discharge pressure is about the same for 60, 80 and 100 g ‎refrigerant charges, but significant increase in discharge pressure was observed as the ‎refrigerant charge increased to 120 g. The rate of increase in the refrigerating capacity and the ‎COP with respect to evaporator temperature for refrigerant charge of 60 g to 100 g are higher ‎than that for refrigerant charge of 120 g. Highest refrigerating capacity and COP of 4.404 kW ‎and 3.1, respectively, were obtained in the cooler refrigerator with 100 g charge. Generally, ‎the best performance of the cooler was obtained with refrigerant charge of 100 g and increase ‎in the charge beyond 100 g affected the performance of the cooler negatively.