Analysis on heat transfer and pressure drop of a microchannel heat sink with dimples and vortex generators

Abstract

The combination of vortex generators (VGs) and dimples on a microchannel heat sink is proposed to improve the heat transfer performance on a cooling surface with a constant heat flux of 100 W/cm2. Three pairs of VGs are evenly distributed along flow direction, while the dimples are placed downstream of VGs with the same intervals. Numerical simulations are performed with de-ionized water as working fluid for the Reynolds number in the range from 167 to 834. The result indicates that the adoption of VGs and dimples could improve the heat transfer performance by 23.4–59.8% with a penalty of apparent friction factor increased by 22.1–54.4% compared with smooth microchannel. The intensity of vortices induced by VGs is much stronger than those induced by dimples and the interaction between dimples and VGs is advantageous for heat transfer enhancement. Furthermore, the VGs arranged in a “common flow down” configuration have better heat transfer performance than VGs in a “common flow up” configuration. The parameter study manifests that VGs with a height ratio of h/Hc = 0.6 and attack angle of β = 45° present the best thermal hydraulic performance. The optimized value of R reaches as high as 1.17–1.28 in the present study.