Performance Analysis and Multi-Objective Optimization of an Offset Plate-Fin Crossflow Heat Exchanger

A compact crossflow offset plate-fin heat exchanger (CPFHE) is widely used in many industrial applications. In this paper, a local sensitivity analysis was performed and a parametric analysis was used to validate the results of the sensitivity analysis and locate the optimum by utilizing the unidirectional search. A new formula for the mass of the CPFHE that includes the masses of fans was introduced. A practical approach was used to formulate multi-objective optimization problems through which the total annual relative cost, heat rate, effectiveness, and mass of the CPFHE were optimized separately and simultaneously relative to 13 optimization design variables using a genetic algorithm and the direct search method. The main optimization results showed that the effectiveness of the CPFHE could be increased by 9% through performing the optimization process relative to an additional influential variable, achieving a remarkable 0.9812. The actual value for the optimized mass of the CPFHE reported in the literature (a very small volume with huge pressure drops and massive fans) is many times greater than the optimized mass of this study. The distributions of the Pareto-optimal point solutions of multi-objective optimization results for three different conflict-objective functions were plotted and showed that all points are nondominated.