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This paper presents performance comparison between different liquid metal based nanofluids termed as nano-liquid-metal-fluids in a microchannel heat sink in order to achieve ultimate cooling solutions without sacrificing the compact structure and heavy computing speed. The hydraulic and thermal performance of nanofluids having five different liquid metals (Ga, GaIn, EGaIn, GaSn, EGaInSn) as base fluid and four different nanoparticles (CNT, Al2O3, Cu, diamond) as solute are evaluated comparing with water based nanofluids. Three-dimensional flow inside miniaturized channels are predicted using single-phase and two-phase numerical simulations. Numerical models are validated against data obtained from experimental studies from literature. Three different grids are developed and several element sizes were compared to obtain the grid independence. Upon evaluation, the study can point out that liquid metal based nanofluids can generate much superior heat transport characteristics with more than 3.41 times higher heat transfer coefficient compared to conventional water based nanofluids. GaIn-CNT combination exhibits the best thermal solution possible with a heat transfer coefficient increment of 2.68%, 17.19%, 22.16%, 2.62% over CNT particle-based EGaIn, EGaInSn, Ga, GaSn liquid metal, respectively for Re = 750. Considering hydraulic performance, PEC (performance evaluation criterion) has been introduced and Ga based nanofluids are found to be most effective in this perspective. The effect on overall cooling effectiveness has also been carried out with a detailed particle concentration study. This study paves the pathway of using these extraordinary coolants in mini/micro channel heat sinks.

Microchannel heat sink plays a vital role in removing a considerable amount of heat flux from a small surface area from different electronic devices. In recent times, the rapid development of electronic devices requires the improvement of these heat sinks to a greater extent. In this aspect, the selection of appropriate substrate materials of the heat sinks is of vital importance. In this paper, three boron-based ultra-high temperature ceramic materials (ZrB2, TiB2, and HfB2) are compared as a substrate material for the microchannel heat sink using a numerical approach. The fluid flow and heat transfer are analyzed using the finite volume method. The results showed that the maximum temperature of the heat source didn’t exceed 355K at 3.6MWm-2 for any material. The results also indicated HfB2 and TiB2 to be more useful as a substrate material than ZrB2. By applying 3.6 MWm-2 heat flux at the source, the maximum obtained surface heat transfer coefficient was 175.2 KWm-2K-1 in a heat sink having substrate material HfB2.