Influence of graphene oxide nanosheets on the stability and thermal conductivity of nanofluids

Abstract

Many theoretical and experimental studies on heat transfer and flow behavior of nanofluids have been conducted, and the results show that nanofluids significantly enhance heat transfer. However, less attention has been paid to obtain the thermal conductivity of nanofluids and their stability using molecular simulations which are applied by investigators to explain the molecular mechanisms of nanoscale phenomena. In this work, the stability of water–ethylene glycol-based graphene oxide (GO) nanofluids was investigated by classical molecular dynamics simulations in which the kinetic energy, radial distribution function and intensity diagrams were obtained. The obtained results confirmed the stability of nanofluids. Also, the thermal conductivity of nanofluids was studied by reverse non-equilibrium molecular dynamics method at different ratios of water–ethylene glycol as base fluids and various amounts of graphene oxide as nanoparticles. The results show that the thermal conductivity of nanofluids increases with the amount of graphene oxide nanosheets. For example, the thermal conductivity of water–ethylene glycol (75/25%)-based nanofluid containing 3, 4 and 5% of GO nanosheets was increased by 24, 28 and 33%, respectively, at 46.7 °C. Finally, the theoretical models on heat transfer and flow behavior of nanofluids were employed to validate the molecular simulation results. The obtained thermal conductivity results are in good agreement with theoretical models.