Numerical Investigation of Rough Micro- and Mini-channel Heat Sinks for Varying Aspect ratio

Abstract

Numerical simulations are performed to study the impact of aspect ratio on the micro- and mini-channel heat sink behaviours in the presence of sinusoidal surface roughness. A CFD model is first validated with the relevant reference data for laminar flow conditions using ANSYS-Fluent analysis. The found results of this validation study show that the simulation results agree well with the reference data. The considered channel height, absolute roughness height and diameter are 250 µm, 30 µm and 366 to 374 µm, respectively. The top and bottom rough walls are under constant heat flux conditions, while other walls are adiabatic with air as the working fluid. The micro- and mini-channels with long wetted perimeter and lower aspect ratio have shown more convective heat transfer but with slightly higher frictional resistance. The convective heat transfer and thermal performance factor both improve with the increase in Reynolds number where all the values are higher than 1. The maximum value of the thermal performance factor is noted up to 1.6 for the channel having aspect ratio of 0.038 (Reynolds number = 250). This study shows that micro- and mini-channel heat sinks are sensitive to surface roughness, Reynolds number where varying aspect ratio have influence on both flow and heat transfer performances in laminar regime.