Numerical Analysis on Laminar Heat Transfer Intensification Using Wavy-Twisted Oval Tubes

The present research examines the laminar fluid flow and heat transfer characteristics within a novel swirling flow generator. The geometry is a tube with an oval cross-section that is twistedly swept along a wavy path, named wavy-twisted oval tube (WTOT). This study considers aniline, a fluid with temperature-dependent properties, as the working medium. The effects of Reynolds number (Re = 200, 300, 400, 600, and 900), and twist ratio (TR = 3.3 and 6.6) on flow patterns, friction factor, Nusselt number, and thermodynamic second law efficiency are numerically evaluated, and some comparisons are made against twisted oval tubes (TOTs) and plain oval tubes (POTs). Due to the impact of centrifugal forces on the swirling flow, transverse velocity fields are intensified, resulting in greater temperature uniformity inside WTOTs. The numerical results show that the heat transfer rate can be improved by 34-78% and 201–332% when WTOTs are used instead of TOTs and POTs, respectively. Additionally, the WTOTs cause an increase in pressure drop of up to 68% and 335% compared to TOTs and POTs, respectively. From a thermodynamic perspective, WTOTs are responsible for a reduction in entropy generation by a maximum of 66.5% and an enhancement in second law efficiency by up to 195%.