Thermal and viscosity properties of inhomogeneous fluids with
suspended graphene nanoparticles
The use of nanofluids in a wide variety of applications is promising, but poor suspension stability of nanoparticles in the solution hinders the further development of nanofluids applications. The present study aims to provide a fundamental understanding of the thermal and viscosity properties of inhomogeneous fluids with suspended graphene nanoparticles. A graphite material is exfoliated to form graphene particles, and the effect of nanoparticle volume fraction on the material properties of inhomogeneous fluids with suspended graphene nanoparticles is investigated at different temperatures or under oxidation conditions. Particular emphasis is placed upon the effect of nanoparticle volume fraction on the material properties of inhomogeneous fluids with suspended graphene nanoparticles. The results indicate that the bottom-up approach produces low quantities with high quality and large flakes whereas the top-down approach yields a high concentration of suspended flakes with a low yield of mono-layer graphene. Smaller dispersions result in ease of addition of graphene to other desirable emulsions to enhance the uniform coating matrix for protection attributes graphene can provide to the coating. The pressure drop allows the liquid precursor to flow and homogenizes the pass-through liquid of the liquid precursor that contains thin layers of graphene. The phonon Raman scattering changes are correlated with structural changes and defects associated with the hydroxyl and epoxy groups in the basal plane and a variety of alkyl and oxygen-containing functional groups terminating the edges. Graphene-containing nanofluids provide several advantages over the conventional fluids, including thermal conductivities far above those of traditional solid-liquid suspensions, a nonlinear relationship between thermal conductivity and concentration, strongly temperature-dependent thermal conductivity, and a significant increase in critical heat flux. Stability of the nanoparticle suspension is especially essential for practical industrial applications. Introduction of nanoparticles to the fluid changes density, thermal conductivity viscosity, and specific heat. The functionalization process decreases enhancements in thermal conductivity due to formation of surface oxides. In development of nanofluids for heat transfer a fine balance needs to be obtained between increases in thermal conductivity and viscosity.
Keywords: Graphene; Nanoparticles; Thermal properties; Viscosity properties; Fluids; Graphite