Thermal and Hydraulic Performance of a Rectangular Duct With Multiple V-Shaped Ribs

Abstract

Experiments have been carried out to investigate the performance of a new swirl flow duct which is suitable for compact heat exchangers such as radiators. The ducts tested have rectangular cross sections with aspect ratio 1 to 8, and multiple V-shaped ribs are attached to the wide walls in a staggered arrangement such that square secondary flow cells are established. A previous investigation has shown that multiple V-shaped ribs may provide greater heat transfer enhancement than angled straight ribs and V-shaped ribs at Reynolds numbers below 2000. The data are presented as j and f factors for Reynolds numbers from 500 to 15,000, and correlations are obtained for the influence of rib height (0.1 < e/H < 0.2), rib pitch (3 < p/H < 7), and rib angle (15 deg < Φ < 45 deg). It was found that a rib angle of 45 deg provided the highest j/f ratio, while increasing the rib height or decreasing the rib pitch lowers the j/f ratio.