Exergetic and performance assessment of superheated vapor compression refrigeration systems under variable compressor efficiency using conventional and low-GWP refrigerants

Abstract This research presents a comprehensive exergetic and performance assessment of vapor compression refrigeration (VCR) systems integrated with a superheater, employing four refrigerants from different categories, namely R134a, R1234yf, CO₂, and R410a. All selected refrigerants possess zero ozone depletion potential (ODP). Among them, R1234yf and CO₂ are identified as low global warming potential (GWP) alternatives, while R134a and R410a represent conventional high-GWP refrigerants. The objective of this study is to evaluate the thermodynamic performance and environmental sustainability of the system through a detailed comparative analysis of these refrigerants. Exergy analysis, recognized as an effective tool for quantifying system inefficiencies and component-wise irreversibilities, is applied to the major elements of the refrigeration cycle, including the evaporator, condenser, expansion device, and compressor. Governing equations for exergetic efficiency and exergy destruction are formulated, and the system performance is examined under both superheated and non-superheated operating conditions. In addition, the influence of compressor isentropic efficiency is investigated over a wide range from 0.65 to 0.85 to assess its impact on overall system performance. The modeling and simulations are carried out using the commercial software Ecosim PROOSIS under varying operating conditions, with evaporator temperatures ranging from 248 to 298 K and condenser temperatures from 313 to 338 K. The results indicate that R134a achieves the highest exergetic efficiency among the refrigerants considered, followed closely by R1234yf, highlighting its strong potential as an environmentally benign replacement. An increase in both evaporator and condenser temperatures leads to a reduction in exergetic efficiency for all refrigerants, whereas a higher compressor isentropic efficiency significantly improves system performance. Furthermore, the incorporation of a superheater enhances the overall exergetic efficiency and reduces irreversibilities within the system. Overall, this study provides a valuable insights into combined effects of refrigerant selection, superheating, and compressor efficiency on the performance of VCR systems. The findings emphasize the feasibility of adopting low-GWP refrigerants, particularly R1234yf and CO₂, for developing energy-efficient and environmentally sustainable refrigeration technologies.