Design optimization of baffle in heat exchanger for improving flow maldistribution and pressure drop

Abstract

Heat exchangers (HEs) are used in process industries such as power plants and petroleum refineries. It is important to minimize flow maldistribution as well as pressure drop for high performance of HE. A baffle is often installed in the header part of HE in order to achieve the flow uniformity, but the hole sizes of baffle are determined by the engineer's experience. In this paper, a multi-objective design optimization for minimizing both the flow maldistribution and the pressure drop is performed using numerical simulation. The hole sizes in the baffle are taken as the design variables. In addition, the angle of baffle is newly considered. By introducing the angle of baffle, it is expected that fluid will smoothly flow into the edge of the header. The numerical simulation using computational fluid dynamics (CFD) is so intensive that sequential approximate optimization that response surface is repeatedly constructed and optimized is adopted to determine the optimal solution with a small number of simulations. Through the numerical result, the pareto-frontier between the flow maldistribution and the pressure drop is identified. It is found from the numerical result that several small vortexes are generated in the optimal configuration. This indicates that generating small vortexes will play an important role for improving the performance of HE.