Exergy and energy analysis of a vapour compression refrigeration system for the investigation of a new refrigerant to be used on board the ships

Abstract

This paper investigates the comparison between single stage vapour compression refrigeration cycles working with R134a - a traditional refrigerant for marine applications, and R435A - a new refrigerant having Dimethyleter (DME) 80% and R152a 20%. Since R134a shows a high GWP (Global Warming Potential), in the next future this refrigerant will be a subject for replacement. The new refrigerant taken into discussion here, R435A, shows a much lower GWP (3 compared with 1300 of R134a). The study allows the investigation of the performance of the cycles working with these two refrigerants, within a thermodynamic analysis, based on both first and second laws of thermodynamics. This kind of research is a strong tool used in design, optimisation and performance assessment of refrigeration systems. In the present paper are analysed the influence of evaporation temperatures on first and second law efficiencies and on exergy losses in the system. The results are obtained when this temperature varies in the range (248÷278) K. These results reveal the fact that R435A is a viable solution for R134a replacement, since average COP for R435A is about 35% higher than for R134a, the average exergy loss is around 40% smaller and the average exergy efficiency is approximately 35% higher.