Design and multi-objective optimization of heat exchangers for refrigerators

In this study, a detailed thermodynamic model for a refrigerator based on an irreversible Carnot cycle is developed with the focus on forced-air heat-exchangers. A multi-objective optimization procedure is implemented to find optimal design values for design variables. Minimizations of energy consumption and material cost were the two objectives considered. Since these objectives are conflicting, no single design will satisfy both simultaneously. The result of this research is a set of multiple optimum solutions, which are called ‘Pareto optimal solutions’. Air and refrigerant side correlations were combined with an elemental approach to model the heat exchangers. This paper presents a detailed design model development. A limited validation is presented with experimental test-data obtained from a typical household refrigerator. Detailed simulation models are typically complex and computationally demanding. An optimization algorithm requires several evaluations of such models. Response surface based metamodels for objective functions were used to save computational effort. A genetic-algorithm based optimization tool is used for multi-criteria optimization.