Rheological Behavior of Water-Ethylene Glycol Based Graphene Oxide Nanofluids

Abstract

Traditionally water-ethylene glycol mixture based nanofluids are used in cold regions as a coolant in the car radiators. In the present study, the rheological properties of water-ethylene glycol based graphene oxide nanofluid are studied using Non-Equilibrium Molecular Dynamics (NEMD) method at different temperatures, volume concentrations, and shear rates. NEMD simulations are performed with considering 75/25, 60/40, and 40/60 ratios of water/ethylene glycol as the base fluids at volume concentrations of 3%, 4%, and 5% graphene oxide nanosheets. The results, which demonstrated good agreement with experimental data, show that the viscosity and density of base fluids significantly decrease with temperature and increases with ethylene glycol volume fraction. Also, the viscosity and density of nanofluids depends directly on the volume concentrations of nanoparticles and decreases with increasing temperature. For example, at 289.85 K, the viscosity of water (75%)-ethylene glycol (25%) based nanofluids containing 3%, 4% and 5% volume concentrations of nanoparticles increased by 33%, 43%, and 56%, respectively. Similarly, the density of the same nanofluids increased by 1%, 1.7 %, and 2.2%, respectively. Moreover, the theoretical models confirm the obtained results. According to the shear rate analysis, the water-ethylene glycol based graphene oxide nanofluid behaves as a non-Newtonian fluid.