Performance Optimization of Sustainable Building Cooling Systems Employing Low-GWP Zeotropic Refrigerants

Abstract

Performance assessment of three low-GWP zeotropic alternatives to existing refrigerants for vapor compression cooling machines is conducted in this paper. Refrigerants considered are low-GWP drop-in alternatives R-454B (GWP 466), R-452B (GWP 698), and R-444B (GWP 295), as well as commonly used comparison refrigerants R-32, R-410A, and R-407C. CoolProp property tables and SciPy interpolation were utilized in order to calculate COP, second-law (exergy) efficiency, compression ratio, temperature glide, and TEWI over a range of evaporating temperatures from −5 °C to 15 °C and condensing temperatures from 35 °C to 55 °C. In addition, superheat and subcooling values were optimized using differential evolution to obtain maximum COP. Simulation results indicate that R-444B has the highest nominal COP of 5.60 as well as the lowest TEWI of 28 tonne CO₂-eq over a 15-year lifespan. R-454B was also found to exhibit competitive performance (COP of 3.99), with a low GWP within legislative limits. COP–GWP Pareto optimality indicates R-444B and R-454B to be the two leading candidates as drop-in replacements to higher GWP refrigerants for building cooling.