Advances in the modelling of concentration-dependent relative viscosity data for nanofluids by introducing the Dispersion Factor

Abstract

The viscosity ratio (relative viscosity) of a nanofluid to its base liquid is related to the nanoparticle volume fraction by various developed theoretical and empirical equations. However, the theoretical framework used up to now is often inadequate for modelling experimental data. Now, a new parameter denoted as the Dispersion Factor (DF) is proposed to advance the accurate modelling of relative viscosities of nanofluids dependent on nanoparticle volume fraction. Literature data of TiO2, γ-Al2O3 and SiO2 nanofluids have been selected and subjected to our new theoretical treatment using the Chen equation adapted with the Dispersion Factor to model the relative viscosity in relation to the nanoparticle volume fractions. A much better agreement with the experimental data has been obtained. The value of DF that is identified by the mathematical modelling of relative viscosity data reflects the comprehensive effect of particle size, shape and chemical composition on the interactions between the nanoparticle and the base liquid on the one hand, and solvated nanoparticle and nanoparticle interactions on the other hand. The DF parameter may present a possible tool that can be used to tailor and tune the nanofluid design to meet specific application requirements.