Development of a cooling capacity correlation for aluminum tube evaporator to enhance refrigerator efficiency using R600a refrigerant

Abstract This paper focuses on the cooling capacity analysis of aluminium tube evaporator for cooling compartments in domestic refrigerator. The study adapted a framework combining analytical and experimental analyses to investigate the influence of evaporator tube length on the cooling capacity of the freezer and refrigerator. Convective heat transfer co-efficient based on two-phase flow was calculated under four different correlations considering a domestic refrigerator of 246 L volume using R600a refrigerant. Cooling capacity was calculated based on the product of cooling capacity factor and cubic root of volume signifying the heat loss. The cooling capacity factor provides a concrete understanding of the variation in evaporator tube length as a function of different parameters such as thermal conductivity, thickness, temperature etc. An optimized evaporator tube length was considered for the freezer and refrigerator of 246 L domestic refrigerator bestowing uniform cooling capacity factor for four different correlations albeit convective heat transfer coefficient (HTC) varied significantly. To validate the optimized evaporator tube lengths, cooling capacity was examined through pull-down tests for two different commercially available samples of varying volumes and tube lengths for the freezer and refrigerator, as well as the optimized sample with the largest volume. A comparison of the cooling capacity of the two samples and the optimized sample showed that the optimized sample exhibited a higher cooling capacity and achieved temperature convergence earlier. Furthermore, the energy analysis conducted on all samples revealed that optimized sample attained the highest energy efficiency ratio (EER) and least Energy Efficiency Index (EEI).