Numerical Study on Flow and Heat Transfer of Water and Liquid Metals Within Micro-Scale Heat Sinks for High Heat Dissipation Rate Applications

TL;DR

This study numerically investigates how wall slip affects flow and heat transfer in micro-scale heat sinks, revealing that slip enhances thermal performance and reduces pumping power.

Contribution

It provides new insights into the impact of wall slip on thermalhydraulic performance, demonstrating performance improvements with slip boundary conditions in micro heat sinks.

Findings

Slip length of 2 microns improves heat sink performance by 6%.

Channel average Nusselt number increases by 4%.

Pumping power decreases by 8% with slip boundary conditions.

Abstract

Compact and small-scale heat exchangers can handle high heat dissipation rates due to their large surface area to volume ratios. Applications involving high heat dissipation rates include, but are not limited to, compact microelectronic processing units, high power laser arrays, fuel cells, as well as fission batteries. Low maintenance cost, small size and dimensions, as well as high convective heat transfer coefficients, make micro-scale heat sinks an efficient and reliable cooling solution for applications with high heat dissipation rates. Despite these advantages, the large pressure drop that occurs within micro-scale heat sinks has restricted their utilization. Slip at the walls of microchannels has been reported to reduce friction factor up to 30%, depending on the hydraulic diameter of the microchannel. Numerical investigations are conducted to comprehensively investigate the effect of slip at walls on friction factor and Nusselt number of liquid flows in micro-scale heat sinks. At the same mass flow rate and inlet Reynolds number, obtained results suggest that slip length on the order of 2 microns enhances the overall thermalhydraulic performance of micro heat sinks by almost 6% in comparison with no-slip boundary conditions. 4% increase is observed in channel average Nusselt number while pumping power reduces by 8% in comparison with no-slip boundary condition.