Comparative study and multi-objective optimization of plate-fin recuperators applied in 200 kW microturbines based on non-dominated sorting and normalization method considering recuperator effectiveness, exergy efficiency and total cost

Abstract

The current study aims to simultaneously and comprehensively investigate the performance of four types of recuperative heat exchangers applied in 200 kW microturbines by using numerical method. Different fin configurations including rectangular, triangular, louver and offset strip fins are employed in the recuperators to enhance the heat transfer rate. Additionally, the calculations are separately undertaken for both counter and cross-flow arrangements. To achieve the best performance, a three-objective optimization problem is solved using Non-dominated Sorting Genetic Algorithm (NSGA-II). Recuperator effectiveness and exergy efficiency and total cost are considered as the objective functions. The recuperator effectiveness and exergy efficiency are maximized and the recuperator total cost is minimized, simultaneously. The results of each optimization are delineated by a set of designs using three dimensional Pareto-optimal fronts. Maximum cycle thermal and exergy efficiencies and NPV occur in the counter-flow recuperator employing offset strip fin and the values are found to be 39.1275%, 36.7431% and 3088164 $, respectively. A sensitivity analysis of variation in recuperator effectiveness and exergy efficiency and total cost with changes in design parameters of the plate-fin recuperators employing louver and offset strip fins with counter-flow arrangement is performed. Finally, all the optimal designs obtained from the Pareto diagrams are compared to determine the optimum designs using normalization method and non-dominated sorting concept. According to the comparisons, offset strip fin and louver fin with counter flow arrangement show better performance.