Application of Taguchi method in the numerical analysis of fluid flow and heat transfer around a flat tube with various axial ratios

Abstract

In this paper, the behavior of airflow over flat and circular tubes is investigated in terms of aerodynamics and heat transfer simultaneously to determine the most effective factors and their optimum levels. Three types of flat tubes, with axial ratios of 1.5, 2, and 2.5, are considered in comparison with circular tubes. Two boundary conditions of constant temperature and constant heat flux are applied on the tube wall. By using the Taguchi method and analysis of variance (ANOVA), the L16 array is investigated statistically. The drag force coefficient, the Nusselt number, and the thermal-hydraulic performance are calculated, as well as the optimal values and contributions of design variables. The results show that, while the axial ratio has a major effect on the drag force, it has little impact on the rate of heat transfer, and the tube wall boundary condition would be more effective. However, the axial ratio of the tube has the greatest impact on thermal-hydraulic performance. In terms of flow behavior, the vortex shedding phenomenon is eliminated in most cases of flat tubes. By utilizing the Taguchi method and statistical analysis, the volume of calculations is reduced by 50% without considering the reduction of data analysis time.