Comparative Thermodynamic Study of Refrigerants to Select the Best Environment-Friendly Refrigerant for Use in a Solar Ejector Cooling System

摘要

In this study, a solar ejector cooling system is theoretically analyzed to evaluate refrigerants and determine their performance characteristics and environment-friendly nature for a fixed ejector geometry under a set of standard operating conditions. The results show that the refrigerant R1234yf is the best choice for the cycle, and is an environment-friendly refrigerant with thermo-physical properties similar to that of R134a. Moreover, it has a high entrainment ratio and is cheap when compared to other refrigerants, nonflammable, and safe. The results indicate that the cooling cycle COP increases during the day hours as the generator temperature increases and reaches a maximum value of 0.59 at an optimum generator temperature of 86 degrees C in the middle of the day. The overall efficiency of the system varied in the range 38-45%. Furthermore, it was found that increasing the generator pressure by 40% reduced the COP by 58.5% and increased the critical backpressure by 27.3%.