Optimization of the Angle of Attack of Delta-Winglet Vortex Generators Over a Bank of Elliptical-Tubes Heat Exchanger

Abstract

In order to reach a more efficient and compact heat exchanger, it is essential to optimize the design, having in mind the impact of different geometrical parameters. Many of the previously cited studies in the area of heat transfer enhancement using vortex generators were confined only to defined points in the possible design space. Thus, a multi-objective optimization study is particularly suitable in order to cover this space entirely. A CFD simulation along with Pareto method were used to simulate the air flow and heat transfer and optimize the design parameters. The angle of attack of a pair of delta-winglets mounted behind each tube is varied between β = −90° and β = +90°. Three elliptical tube rows with inline arrangements are investigated for Reynolds numbers from 500 to 1500 (based on the inlet properties). Use of delta-winglets as heat transfer enhancement elements increases the performance of elliptical-tubes heat exchanger. This enhancement is mainly due to the fact that delta-winglets increase the level of vorticity inside these devices and thus the mixing of the fluid is enhanced.