Comparative Performance of Low-GWP Refrigerants as Substitutes for R134a in a Vapor Compression Refrigeration System

This study predicts numerically the performance of low-GWP refrigerants [R152a, R1234yf and R1234ze(E)] as an alternative to R134a in a vapor compression refrigeration system. The plate heat exchanger was used as a condenser, and the appropriate correlations available in the published literature were used to predict the heat transfer coefficients and friction factors of refrigerants during condensation. Drop-in analysis based on the same conditions of the cooling medium (water) was considered, and the system was modeled in EES software. For this analysis, the inlet temperature of the water was varied from 15 to 40 °C as an input, and its effect on the performance parameters (condensation temperature, input power, discharge temperature, compression ratio, cooling capacity and COP) was analyzed and compared with R134a. The correlation used in this study predicts the better performance of R152a and R1234ze(E) as their heat transfer coefficient values are found to be 67–72% and 0.85–3% higher at condensation temperatures of 40–55 °C, respectively, when compared with R134a. The trends for the predicted frictional pressure drops are also found to be similar. For the drop-in analysis based on the same cooling medium conditions, simulation results reveal better performance for R152a and R1234ze(E). R152a shows 6.3–11% higher COP relative to R134a, whereas R1234yf shows lower COP of 7.6–12%, for the range of cooling water inlet temperatures considered in this study. Simulation results conclude that R152a seems more adequate refrigerant as an alternative of R134a in vapor compression refrigeration system.