Heat transfer and fluid flow analysis of microchannel heat sinks with periodic vertical porous ribs

Abstract

In this study, a detailed numerical analysis of the fluid flow and heat transfer of a three-dimensional microchannel is performed to evaluate the effect of using periodic vertical porous and solid ribs with various geometrical shapes, including rectangular, elliptical, isosceles triangular, backward triangular and forward triangular on the walls of this microchannel. Darcy-Brinkman-Forchheimer equations are used to model transport through the porous medium. The results for microchannels with solid ribs and with porous ribs are compared to each other. It is found that at the lowest studied inlet velocity (uin=0.25m/s), for the rib heights of Hr=0.025mm,0.05mmand0.07mm, the average Nusselt number of the porous-rib microchannel is 2.16, 2.1 and 1.3 times greater than the solid case, respectively; and, 2.505, 3.62 and 4.01 times greater than the no-ribs microchannel, respectively. It is found that for the same increase in the Nusselt number, the porous ribs induces much less pressure drop compared to the solid cases. Accounting the thermal and hydraulic performance simultaneously, Figure of Merit (FOM) is calculated. The results show that porous ribs lead in much better FOMs compared to the solid ribs case. Effects of the height, porosity and Darcy number of the ribs are also investigated.