PERFORMANCE INVESTIGATION OF FOUR ECO-FRIENDLY REFRIGERANTS AS RETROFITS FOR DOMESTIC REFRIGERATORS

Abstract

This paper examines eco-friendly hydrocarbon refrigerants as substitutes for R134a in vapour compression refrigeration systems. It details the retrofitting of an existing system for R134a with modifications including a copper capillary tube, filter drier, refrigerant charge adjustment kit for hydrocarbons, and a sub-cooling coil to improve cooling capacity and energy efficiency while minimizing environmental impact. It explores retrofitted systems using Liquefied Petroleum Gas (LPG), Propane (R290), Iso-butane (R600a), and Carbon dioxide (R744), comparing their effectiveness to R134a through experimental analysis. R290 refrigerant outperforms others in pull down times, achieving cooling in 15 minutes at -10°C evaporator and 40°C condenser temperatures, followed by R600a, LPG, and R744. R134a is the least energy efficient at 850W and has the longest pull-down time of 22 minutes. LPG, propane, and iso-butane are more efficient and eco-friendly alternatives to R134a, consuming 644W to 805W with better pull-down time, power consumption, and lower pressure ratios. LPG exhibits a refrigerating effect of 150 kJ/kg with a COP of 3.50 and 78.7% efficiency. R290 has a superior effect at 240 kJ/kg, COP of 3.45, and 76.7% efficiency, followed by R600a at 230 kJ/kg, COP of 3.42, and 76.3% efficiency. R744, however, shows the lowest refrigerating effect at 140 kJ/kg, COP of 2.30, and 66.5% efficiency, while R134a, despite its low cooling capacity, achieves 78.1% efficiency. Hydrocarbon refrigerants are eco-friendly alternatives to R134a, with R600a being the most effective. R290 and LPG are also suitable substitutes for domestic refrigerators during phase-out, as they help reduce energy consumption.