Equilibrium Molecular Dynamics Simulation Study on the Effect of Nanoparticle Loading and Size on Thermal Conductivity of Nanofluids

Abstract

Nanofluids have been proposed as a route for surpassing the performance of currently available heat transfer liquids for better thermal management needed in many diverse industries and research laboratories. Recent experiments on nanofluids have indicated a significant increase in thermal conductivity with 0.5 to 2% of nanoparticle loading in comparison to that of the base fluid. But the extent of thermal conductivity enhancement sometimes greatly exceeds the predictions of well established classical theories like Maxwell and Hamilton Crosser theory. In addition to that, these classical theories can not explain the temperature and nanoparticle size dependency of nanofluid thermal conductivity. Atomistic simulation like molecular dynamics simulation can be a very helpful tool to model the enhanced nanoscale thermal conduction and predict thermal conductivities in different situations. In this study a model nanofluid system of copper nanoparticles in argon base fluid is successfully modeled by equilibrium molecular dynamics simulation in NVT ensemble and thermal conductivities of base fluid and nanofluids are computed using Green Kubo method. The interatomic interactions between solid copper nanoparticles, base liquid argon atoms and between solid copper and liquid argon are modeled by Lennard Jones potential with appropriate parameters. For different volume fractions of nanoparticle loading, the thermal conductivities are calculated. The nanoparticle size effects on thermal conductivities of nanofluids are also systematically studied. This study indicates the usefulness of MD simulation to calculate thermal conductivity of nanofluid and explore the higher thermal conduction in molecular level.