Enhanced heat transfer mechanism and flow topology of a channel contained with semi-circular hinged V-shaped baffles

Abstract

The current work presents a numerical analysis of heat transfer mechanism and flow topology of channels with V-shaped baffles (VB) and semi-circular hinged V-shaped baffles (SH-VB). The vital purpose of applying SH-VB roughened channels is to induce combined vortex and impinging jets flows and reduce the pressure drop in the channel as compared to the use of VB. The effects of geometric parameters: pitch ratios (PR = 0.5, 1.0, 1.5 and 2.0), blockage ratios (BR = 0.1, 0.15 and 0.2), semi-circular hinge angles (β = 5°, 10° and 15°) were studied in the turbulent region (3000 ≤ Re ≤ 19,000). The study was performed at constant aspect ratio (AR) of 10.0 and V-baffle attack angle of α = 45°. The numerical results showed that the decrease of PR and increase of BR resulted in an increase of heat transfer enhancement and pressure drop. The maximum heat transfer enhancement of 5.57 times over the smooth rectangular channel was found at PR = 0.5, BR = 0.2, β = 10°, and Re = 3000. The numerical results also indicated that SH-VB gave higher heat transfer and thermal enhancement factors (TEF) and lower pressure losses than VB. SH-VB provided higher Nu/Nu0, lower f/f0 and higher TEF than VB by around 1.73–8.98%, 5.41–26.84% and 4.51–15.22%, respectively depending on Re, BR, PR and β. The optimum parameters of SH-VB which gave the maximum TEF at 2.6, were BR = 0.10, PR = 0.5 and β = 10° at Re = 3000.