Experimental evaluation of low global warming potential refrigerants R600a and R1234yf as alternatives to R134a in household refrigerators: energy and environmental analysis

The urgent need to phase out R134a, due to its significant global warming potential (GWP), has accelerated the search for sustainable alternatives in refrigeration systems. This study presents a comprehensive experimental investigation of R600a and R1234yf as low-GWP retrofit alternatives to R134a in a domestic refrigerator. Performance was assessed for both a 24-hour steady-state analysis and representative 150-minute dynamic operating profiles at a setpoint of +4°C. The results indicate that while all refrigerants maintained the target temperature, R600a was the most efficient, with a daily consumption of 1.631 kWh, whereas R1234yf had the highest consumption at 1.823 kWh. Dynamic profiling revealed that R1234yf’s high fluid density increased capillary tube resistance, pushing peak condenser pressure to 16.02 bar and significantly elevating compressor load and in-rush power peaks (~300 W). In contrast, R600a demonstrated the most stable thermodynamic profile with the lowest discharge temperature (61.47°C) and condenser pressure (5.65 bar), favoring mechanical longevity. Life cycle climate performance (LCCP) analysis confirmed that indirect emissions account for over 98% of the total environmental impact. Despite having a GWP value as low as 4, R1234yf resulted in a higher total LCCP value (5321.85 kgCO2) than R134a (5233.13 kgCO2) due to energy inefficiency in the retrofit scenario. Consequently, R600a, which offers the lowest total carbon footprint (4786.70 kgCO2), was identified as the most sustainable alternative. This study concluded that prioritizing low GWP without accounting for energy efficiency is insufficient to meet climate targets, as operational efficiency remains the primary driver of household appliances’ overall environmental impact.