Study On Optimization Of Multi-process Plate-fin Heat Exchanger Based On Genetic Algorithm

The plate fin heat exchanger is used for lubricating oil heat transfer in aero engine lubricating oil system because of its high heat transfer efficiency,compact structure small volume,light weight and strong adaptability,its main function is to cool the lubricating oil while preheating the fuel.At present,Aeroengines are developing in the direction of high thrust ratio,large airspace,high safety,long life and low operating cost,which puts forward higher requirements for the performance of lubricating oil system.As one of the three major functional components of the lubricating oil system,the Fuel-Lubricating oil heat exchanger is also facing higher challenges.Firstly,the structure optimization of offset fin is studied by genetic algorithm.The fin structure parameters(fin height h,fin length l,fin spacing s,fin thickness t)are taken as design variables,and the heat transfer factor j,friction factor j and JF factor of fins are optimized for the objective function,and the optimal structure configuration of the fins under different objective functions is obtained.On this basis,the effects of fin single structural parameters and combined structural parameters(s/h,t/l and t/s)on fin performance are discussed,and the sensitivity of each objective function to each structural parameter is analyzed.The results show that heat transfer factor j is most sensitive to fin spacing,friction factor f is more sensitive to fin length and fin spacing,JF factor is most sensitive to fin spacing.Furthermore friction factor f is more sensitive to s/h and t/l,and JF factor is more sensitive to t/s,too.Then,the genetic algorithm is used to optimize the structure of the multi-flow plate fin heat exchanger.The fin structure parameters are used as design variables,the weight of the heat exchanger core structure,the number of heat transfer entropy units,the number of pressure entropy units and the total entropy production unit are optimized for the objective function,and the optimal structure configuration of the fins under different objective functions is obtained.On this basis,the influence of fin structure parameters on the performance of the heat exchanger is discussed.The results show that the core structure weight,the number of heat transfer entropy units,the number of pressure entropy units and the total number of entropy units are all sensitive to the change of fin spacing.Finally,the software for structural optimization calculation of offset fin and multi-flow plate-fin heat exchangers is developed by using C++ language.Using the multi-flow plate fin heat exchanger structure optimization calculation software,the core structure weight and the number of pressure entropy generating units were taken as objective functions,respectively,to optimize the 2# heat exchanger(124mm×86mm×78.4mm),and the optimal configuration of heat exchanger under different objective functions was obtained.