Laser fabrication of Cu nanoparticles based nanofluid with enhanced thermal conductivity: Experimental and molecular dynamics studies

Nanofluids are engineered colloidal suspensions of solid nanoparticles in aqueous and non-aqueous base fluids with enhanced thermo-physical characteristics compared to conventional heat transfer fluids (HTFs). In this study, we report on the fabrication of copper nanoparticles-ethylene glycol (CuNPs-EG) nanofluid by using a simple one-step pulsed Nd:YAG laser ablation method to ablate the surface of a pure copper target in EG base fluid under ambient conditions. Structural and morphological analysis confirmed the fabrication of pure spherical shaped CuNPs with average diameter of ~7 nm. Thermal conductivity (k) investigations of CuNPs-EG nanofluid were conducted by using a computational approach where Equilibrium Molecular Dynamics (EMD) simulations integrated with Green-Kubo (EMD-GK) method was used. The obtained EMD-GK results for k were confirmed experimentally through a guarded hot-plate technique within the temperature ranges of 298–318 K. Interestingly, a relative enhancement (η) in the percentage of thermal conductivity of CuNPs-EG nanofluids obtained after an ablation time ta = 5 min was 15% at 318 K, while sample obtained after ta = 30 min showed an enhancement of ~24% in thermal conductivity. These obtained results confirmed the suitability of using a laser based ablation method to fabricate highly efficient nanofluids which could be used as alternatives for conventional HTFs in various heat transfer applications.