Numerical Assessments on Laminar Airflow, Thermal Characteristic, and Performance Improvement in a Round Tube Equipped With Combined Vortex Generators

Abstract

A round tube heat exchanger (RTHE) with combined vortex generators (CVGs) is subjected to numerical assessments of its airflows and thermal characteristics. The CVGs are V‐shaped ribs and rectangular winglets. The effects of CVG arrangement (A‐1, A‐2, and B), blockage ratio ( b 1 / H and b 2 / D ), and airflow direction (+ x , − x ) on airflow and thermal behavior are considered. To solve the numerical problem, a commercial program’s finite volume technique is chosen. Presenting streamlines, fluid temperature distributions, and local Nusselt number contours (on the tube wall) are the numerical findings obtained in the RTHE fitted with the CVG. The study presents the performance analysis of RTHE using dimensionless variables, including the thermal enhancement factor (or thermal performance factor), averaged friction factor, and averaged Nusselt number. The numerical results indicate that the general flow configuration in the RTHE is dramatically altered by the CVG. The mixing quality of the fluid seems to be enhanced. The vortex flows are found through the RTHE. As a result of the vortex flows impinging on the RTHE wall, the thermal boundary layer (T‐BL) over the heat transfer surfaces changes. Enhancing the convective heat transfer coefficient, heat transfer ability, and thermal performance in the RTHE is mostly because of the reduction of the T‐BL thickness. When compared to a smooth round tube, the maximum enhanced heat transfer of the RTHE fitted with the CVG is 13.83 times greater. Furthermore, at Re = 2000, type B, b 1 / D = 0.15, b 2 / D = 0.05, and V‐Upstream scenario, the optimal TEF is 3.81.