Thermodynamic and Exergetic Performance Comparison of R-22, R-134a, R-410A, and R-290

The refrigeration industry is undergoing a fundamental transformation driven by environmental regulations targeting substances with high ozone depletion potential (ODP) and global warming potential (GWP). The Montreal Protocol and its Kigali Amendment mandate progressive phase-out of hydrochlorofluorocarbon (HCFC) R-22 and the phase-down of high-GWP hydrofluorocarbon (HFC) refrigerants including R-134a and R-410A, creating urgent demand for technically and environmentally superior alternatives. This paper presents a comprehensive thermodynamic cycle analysis and second law (exergy) performance comparison of four refrigerants — R-22 (baseline HCFC), R-134a (HFC), R-410A (HFC blend), and R-290 propane (natural hydrocarbon) — in a vapour compression refrigeration system of 3.5 kW (1 TR) cooling capacity. Analysis is conducted over a range of evaporator temperatures (−10 to +15°C) at a fixed condenser temperature of 45°C, with realistic compressor isentropic efficiency of 0.72. Energy analysis determines COP, mass flow rate, compressor work, and discharge temperature. Exergy analysis identifies component-wise irreversibility and second-law efficiency. Environmental assessment quantifies total equivalent warming impact (TEWI) over a 20-year equipment life. Results show that R-290 achieves the highest COP (4.94 at T_evap = 5°C, 11.8% above R-22), lowest compressor work, lowest exergy destruction (0.604 kW total), and best second-law efficiency (65.2%), while having zero ODP and GWP of only 3 — compared to R-22's GWP of 1760. The principal constraint on R-290 adoption is its A3 flammability classification, which requires system design modifications. R-410A provides the best performance among HFC alternatives (COP 4.76) but its GWP of 2088 makes it subject to phase-down. The study provides quantitative performance data to guide refrigerant selection decisions in the Indian refrigeration industry context.