Rheological study of Y₂O₃ nanofluids

This paper investigates the effects of shear rate and temperature on rheological behavior of Yttria (Y₂O₃) based nanofluids experimentally. These nanofluids are potentially useful in high electric field and high temperature environment as well as for nuclear applications. The nanofluids are prepared by two step method. The particle size of nanofluids is characterized by electro-acoustic spectroscopy. Rheology measurements of these nanofluids show typical Newtonian behavior for several volume fractions of Yttria for shear rates above 1s^-1. Below 1s^-1 shear rate the nanofluids show shear thinning behavior that depends on particles concentration. Generally, the effective viscosity of Yttria nanofluids is found to increase linearly up to 44% with particle loading of 5 vol%. The viscosity of these nanofluids follows Arrhenius type relationship with temperature similar to the base fluid behavior. The relative viscosity of these nanofluids has a temperature dependence behavior which contradicts reported observations in literature and can be attributed to the contribution from particle-particle interaction at higher concentrations. This temperature dependence was more pronounced with an increase in concentrations, which indicates that the viscosity increment of nanofluids is not only governed by the base fluid temperature dependence.