Investigating the impact of different SCWSVGs arrangements on thermo-hydrodynamic flow within pillow-plate type heat exchanger

Abstract

This paper introduces an innovative approach aimed at enhancing heat transfer while simultaneously reducing pressure loss in the Pillow-plate type heat exchanger (PPHE) through the utilization of circular welding spots (CWS) with a dual role as vortex generators (VG) and convergent/divergent features. The VGs, strategically positioned in a configuration termed “SCWSVGs” (Staggered circular welding spot vortex generators), are fixed in place to augment heat transfer. This configuration results in an amplified heat transfer coefficient, increased turbulence, and intensified vortices and secondary flow behind the SCWSVGs. The effectiveness of this enhancement strategy is validated through comparisons with experimental data, correlations, and various channel arrangements. Furthermore, the study investigates the impact of SCWSVGs diameters and streamwise pitches (XL) by exploring the variation in the hydraulic diameter to streamwise length ratio (dh/XL) within the range of 0.036 to 0.070. Key parameters in the dataset include Nu, f, (Cx/Cx0)0.33, normalized heat transfer factor (St/St0), RAF, and TEF. Notably, at 1,000 ≤ Re ≤ 16,000, the highest and lowest heat transfer rates are observed for cases 1–5 and cases 15–20, respectively. The (Nu/Nu0)/(f/f0)0.33 reaches up to 67 %, while f decreases by 9 % (Re = 1,000) to 10 % (Re = 16,000) based on two times the streamwise length (XL). Varied XL values result in significant differences in Nu, highlighting the superior performance of PPHE compared to a smooth enclosure channel.