Flow structure and heat transfer in a narrow rectangular channel with different discrete rib arrays

Abstract

Ribs are known to enhance the heat transfer between the energy-carrying fluid and the heat transfer surfaces. A numerical investigation on the turbulent flow and heat transfer behavior in the rectangular channel with inclined broken ribs for three kinds of rib arrays has been conducted. The computations based on the finite volume method with the SIMPLE algorithm have been carried out with Reynolds number ranging from 6700 to 13,400. Shear stress transport (SST) k−ω turbulence model was adopted. The studies of three-dimensional flow structure including vortex structure and turbulent mixing characterized by the turbulence kinetic energy were carried out. The numerical results show that the heat transfer of the inclined broken ribbed channel are improved about 160–230% compared with smooth duct because co-rotating longitudinal vortices are generated on the cross section of channel. In addition, the effects of geometric parameters for ribs on the heat transfer, such as rib height, rib pitch, were analyzed. Overall, the V-type ribbed array shows the best thermal performance factor. For different slope angle of ribs, the 45° case shows the best overall performance for parallel array and W-type array, while in terms of V-type array the slope angle of ribs for the highest overall thermal performance is 30°.