Multi-objective constructal design for a marine boiler considering entropy generation rate and power consumption

Abstract

A marine boiler model composed of the major heat transfer components of evaporator, superheater and economizer is built in this paper. Constructal design for the marine boiler is performed based on the minimization of weighted sum function composed of entropy generation rate and power consumption. It reveals that the triple minimum weighted sum function can be gained by changing the dimensionless tube outer diameters of the evaporator, superheater and economizer. The weighted sum function of the marine boiler is reduced by 25.9% after triple minimizations, and its overall performance is evidently elevated. The multi-objective optimization considering the entropy generation rate and power consumption is further conducted by using NSGA-II, and the Pareto optimal set of the two performance indexes is gained. By using three decision methods to evaluate the Pareto optimal set, the deviation index of the LINMAP decision method is the smallest one. Therefore, the optimal structure obtained by LINMAP decision method is recommended in the marine boiler designs, which satisfies multiple design requirements for the practical boilers.