Numerical simulation and optimization of heat transfer enhancement in a heat exchanger tube fitted with vortex rod inserts

In this work, numerical simulations have been performed to examine the thermal-hydraulic performance in a heat exchanger tube with vortex rod inserts. Analysis of flow characteristics and parametric study is carried out firstly. The results show that multiple vortices have been induced, and the parameters considered, i.e., vortex rod inclination angle (alpha), diameter ratio (d*) and Reynolds number (Re) have a significant effect on the heat transfer and friction factor characteristics in the tube with vortex rods. To achieve the best configuration for the maximum heat transfer enhancement with the minimum pressure drop considering the interactive effects of the parameters. Multi-objective optimization together with artificial neural network has been implemented to search the optimal Pareto front. To evaluate the amount of heat transfer enhancement against pressure drop augmentation, a thermal-hydraulic performance evaluation parameter has been applied, and it is found that the vortex rod with d* = 0.058 and alpha = 57.057 degrees at Re = 426.767 gives the best thermal-hydraulic performance. (C) 2017 Elsevier Ltd. All rights reserved.