Rheological characteristics of CeO2, Al2O3 and their hybrid mixture in ethylene glycol base fluid in the wide range of temperature and concentration

Abstract

In the present work, the rheological behaviour of three different categories of nanofluid samples, 25 nm CeO2/EG, 13 nm Al2O3/EG and the hybrid mixture CeO2–Al2O3 (in 50:50 volume)/EG, was experimentally investigated. The rheology experiments on nanofluid samples were conducted over volumetric concentrations 0.05–1 vol% and temperature of 30–90 °C. An approach to obtain base fluid flow behaviour from two distinct mixtures of nanoparticles is explored for the first time in the present work. The prepared hybrid nanofluid rheological characteristics are influenced by both the contributing CeO2 and Al2O3 nanoparticles. The hybrid nanofluid flow behaviour was similar to the pure ethylene glycol (EG), which makes this hybrid nanofluid very useful in anti-freezing applications. CeO2/EG and Al2O3/EG nanofluids show dilatant nature at higher temperatures. This is due to the clustering of nanoparticles, and the mixture of these substances is shown to reduce their nature. Field emission scanning electron microscope (ESEM) and transmission electron microscopy (TEM) confirm details of the morphology of the nanoparticles. The power-law model was found the best-suited method to explore and compare the rheology behaviour of nanofluids over variation in concentration and temperature.