Numerical analysis of heat transfer and fluid flow characteristics of microchannel heat sinks with streamwise variation of fin height

Abstract

Microchannel heat sinks with uniform fin height often face limitations in balancing heat transfer with pressure drop penalty. The present study addresses this challenge by investigating the effect of streamwise variations of fin height. Numerical simulations are conducted across Reynolds numbers ranging from 200 to 800 under heat fluxes of 150–450 W/cm². Results demonstrate that variable fin height configurations, particularly the arrangement with increasing and decreasing height (IDH), significantly enhance heat transfer compared to uniform fin design of the same average height, while mitigating the pressure drop penalty associated with tall uniform fins (UF). IDH configuration achieved Nusselt number 2.5 times higher than the plain channel, resulting in 32 % improvement in thermal performance. While the pressure drop for IDH was 3.65 times that of the plain channel, the enhancement in heat transfer outweighed the pressure drop penalty. In contrast, UF configuration exhibited the highest Nusselt number (3.86 times the plain channel) but also the highest pressure drop (9 times the plain channel). Streamwise varying fin height introduces variations in cross-sectional area, inducing fluid acceleration, deceleration, and mixing, which enhance heat transfer. The results of this study can be used to enhance the thermal performance of microchannel heat sinks.