The experimental and numerical investigation of novel type conic vortex generator on heat transfer enhancement

Abstract

In this work, experimental and numerical studies are implemented to investigate heat transfer enhancement and Darcy friction factor characteristics of solar air heater [SAH] fitted with novel type conic vortex generators [NTCVGs] on absorber plate. For the purpose of performing the indoor testing of SAH, rectangular duct with an aspect ratio of AR = 10 is utilized. The thermal performance of vortex generators [VGs] is highly dependent on their geometrical configurations. Therefore, the thermal performance of the NTCVG with different attack angles [α = 20°, 30°, 37.5° and 45°], blade angles [β = 30°, 45° and 60°] and scale ratios [S = 0.6:1, 0.8:1, 1:1, 1.2:1 and 1.4:1] are analyzed in the range of Re = 5000–25000. As a result of the experimental work, it is concluded that all the geometrical parameters are determined to be played a crucial role for thermal enhancement factor, TEF. Besides that the optimum attack angle, blade angle and scale ratio at which the highest thermal enhancement factor of TEF = 1.316, is achieved for α = 37.5°, β = 30° and S = 1:1, respectively. Numerical studies are also performed to shed light on the relation between flow structure and the convective heat transfer mechanism by taking experimental boundary conditions into account at Re = 5000 by using the software Fluent, ANSYS 2020 R2. The resulting Reynolds-averaged fluid velocity and vorticity distributions of turbulent flow as well as the temperature and Nusselt number distributions of heated surface are visualized by numerical studies. In addition to that pressure distribution are also presented to investigate the pressure loss behavior of NTCVG at β = 30°, 45° and 60°.