THE PERFORMANCE EVALUATION OF CO_2 TRANSCRITICAL BOOSTER AND R290/R744 CASCADE REFRIGERATION SYSTEMS FOR DIFFERENT CITIES IN TURKEY

摘要

CO_2 as a natural and fully environmentally friendly refrigerant has become more preferable in refrigeration systems in recent years. Since its critical temperature is much lower than that of other refrigerants. It is mostly used in cascade refrigerant systems as a low temperature cycle fluid. On the other hand, CO_2 may be used in single-stage transcritical refrigeration systems. In this study, performance of two natural refrigerant solutions, trans-critical booster CO_2 refrigeration system with ejector and a R290/CO_2 cascade refrigeration system are examined theoretically by using EES software. Operating conditions are determined to represent different climatic regions in Turkey using summer dry bulb temperatures of various cities. The trans-critical and the cascade system are assumed to operate at two different evaporation temperatures of -10°C and -25°C, respectively. The overall EER values for each system with respect to the same ambient and evaporation conditions are compared and evaluated. Finally, performance of both systems has been compared and the appropriate solution for each city has been suggested.