Inducing vortex flow and heat-exchanger performance-assessments in a square duct equipped with modified-orifice vortex-turbulators (MOVT)

Abstract

The increasing global demand for energy has stimulated innovation aimed at optimizing energy usage for both efficiency and cost-effectiveness. Heat exchangers (HTEX) have consequently become a central focus of research, as enhancing their performance is essential for improving overall energy efficiency. Passive heat transfer enhancement techniques, such as the use of vortex turbulators, have attracted considerable attention because they can improve heat transfer without incurring additional energy consumption costs. This study proposes the development of a novel vortex turbulator for a square cross-section HTEX duct by integrating the advantages of existing turbulator designs. The design also considers applicability and operational feasibility for real-world implementation. The resulting device, termed the modified-orifice vortex turbulator (MOVT), is intended to enhance the heat transfer rate (HTR) and overall thermo-hydraulic performance of heat transfer systems. The study investigates the influence of MOVT shapes, categorized into three types: X, Y, and Z. It also examines the MOVT size, defined by the ratio of its thickness (a) to the duct height (H), a/H = 0.05–0.20. Furthermore, the effects of flow direction variations (+x, -x) are analyzed. The entire study is conducted under turbulent flow conditions, with inlet Reynolds numbers ranging from 3000 to 16,000. The numerical simulation results indicate that the HTR increases by up to 4.19 times compared to a plain tube without the MOVT. The best optimum transfer enhancement ratio at similar pumping force or the highest thermal enhancement factor (TEF) of 1.42 is observed with the Y-type MOVT at a thickness-to-height ratio (a/H) of 0.05.