Development of an optimization strategy for insulation thickness of a domestic refrigerator-freezer

The optimization of insulation thickness is very important to increase the performance of domestic refrigerator-freezers (RFs) because of its strong dependency on the heat load through polyurethane-insulated compartments. However, it is very difficult to find the optimum insulation thickness to allow minimum energy consumption at the arbitrarily given COP and internal volume of each compartment. In this study, the optimization process for the insulation thickness was proposed to improve the energy efficiency of a total RF system. This process included the quantitative relationships between the COP and the insulation thickness of each compartment. In addition, the effects of the proposed optimization strategy on the performance of RF were investigated in the bypass two-circuit cycle and the dual-loop cycle. As a result, the energy consumptions of the bypass two-circuit cycle and the dual-loop cycle were reduced by 5.7% and 6.1%, respectively, by applying the proposed optimization strategy.