Exergy analysis and optimization of R600a as a replacement of R134a in a domestic refrigerator system

Exergy analysis was applied to investigate the performance of a domestic refrigerator originally manufactured to use 145 g of R134a. It was found that the highest exergy destruction occurred in the compressor followed by the condenser, capillary tube, evaporator, and superheating coil. Taguchi method was applied to design experiments to minimize exergy destruction while using R600a. Taguchi parameters were selected by the obtained results from R134a and an experiment using 60 g of R600a, which indicated similar results as R134a. Based on the outcomes, R600a charge amount, condenser fan rotational velocity and compressor coefficient of performance were selected for the design. The analysis of variance results indicated that R600a charge amount was the most effective parameter. At the optimum condition, the amount of charge required for R600a was 50 g, 66% lower than R134a one, which not only brings economic advantages, but also significantly reduces the risk of flammability of the hydrocarbon refrigerant.

► Exergy destruction: compressor, condenser, capillary tube and evaporator.
► Optimum: 50 g of R600a, compressor COP of 1.82, condenser fan velocity of 1800.
► The amount of R600a charge is 50 g that is 66% lower than R134a one.
► Total exergy destruction in optimum condition is 45% of the base refrigerator.