Thermal Management Performances of Low Environmental-Impact Metallocene-Catalyzed Poly-α-Olefin (mPAO) Liquid for High-Power-Density Applications

Abstract

Direct-contact liquid cooling has emerged as one of the most effective thermal management techniques for high-power-density applications. In this study, key physical properties, including density, viscosity, heat capacity, and thermal conductivity are experimentally measured and simulated for three different metallocene-catalyzed poly-α-olefin (mPAO) with different branch lengths and numbers. The results indicate minimal differences in density, heat capacity, and thermal conductivity, but a significant change in the viscosity, with longer and more branched molecules exhibiting higher viscosity. A comparative analysis with common coolants highlights mPAO's superior heat transfer and environmental attributes, positioning it as a competitive environmentally friendly coolant. Using molecular dynamics simulations, mPAO's convective heat transfer behavior of mPAOs in nanochannels is examined to discover enhanced convective heat transfer with increased wall-liquid atomic interactions and reduced liquid inter-molecular interactions. These enhancements arise from the denser atomic arrangement in the liquid and closer proximity to the wall. The results indicate that for forced convection under laminar flow in smooth-walled nanochannels, the Nusselt number depends only on the normalized Kapitza length. It is independent of wall and liquid materials.