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

Remarkable thermal conductivity enhancement in Ag—decorated graphene nanocomposites based nanofluid by laser liquid solid interaction in ethylene glycol

We report on the synthesis and enhanced thermal conductivity of stable Ag-decorated 2-D graphene nanocomposite in ethylene glycol based nanofluid by laser liquid solid interaction. A surfactant free nanofluid of Ag nanoparticles anchored onto the 2-D graphene sheets were synthesized using a two-step laser liquid solid interaction approach. In order to understand a pulsed Nd:YAG laser at the fundamental frequency (λ = 1,064 nm) to ablate Ag and graphite composite target submerged in ethylene glycol (EG) to form AgNPs decorated 2-D GNs-EG based nanofluid. From a heat transfer point of view, it was observed that the thermal conductivity of this stable Ag-graphene/EG is significantly enhanced by a factor of about 32.3%; this is highest reported value for a graphene based nanofluid

A novel approach for engineering efficient nanofluids by radiolysis

This contribution reports for the first time the possibility of using radiolysis to engineer stable efficient nanofluids which exhibit an enhanced thermal conductivity. The validation was confirmed on Ag-H2O and Ag-C2H6O2 nanofluids fabricated via g-radiolysis within the mild dose range of 0.95 × 103–2.45 × 103 Gray. The enhanced thermal conductivity of Ag-H2O and Ag-C2H6O2 nanofluids, was found to be g-radiations dose dependent. In the latter case of Ag-C2H6O2 nanofluid, the relative enhancement in the temperature range of 25–50 °C was found to be 8.89%, 11.54%, 18.69%, 23.57% and 18.45% for D1 = 0.95 × 103 Gray, D2 = 1.2 × 103 Gray, D3 = 1.54 × 103 Gray, D4 = 1.80 × 103 Gray and D5 = 2.45 × 103 Gray respectively. Yet not optimized, an enhancement of the effective thermal conductivity as much as 23.57% relatively to pure C2H6O2 was observed in stable Ag-C2H6O2 nanofluids. Equivalent results were obtained with Ag-H2O