The influence of particle size on the viscosity of water based ZnO nanofluid

Abstract

This experimental work investigated, the effect of ZnO particles’ size on the water-based nanofluid viscosity. Nanofluid samples with 0.5, 0.75, and 1% volume concentrations were prepared using 20 and 50∼150 nm ZnO nanoparticle sizes. Their viscosity was determined at 20, 30, 40, 50, and 60°C. Scanning electron microscopy was employed to investigate the morphology of the nanoparticles. The maximum relative viscosity was measured for 1% ZnO (50∼150 nm) as 1.35 times water. The stability of samples was evaluated for 1% ZnO (20 nm) and 1% ZnO (50∼150 nm) by measuring their Zeta potential values which were −21.4 mV and –23.1 mV, respectively. The correlation for the dynamic viscosity using measured data was compared with well-known ones. The offered correlation has R2 = 0.988, Radj2 = 0.987, and ±5.58% maximum deviation. The results showed that 12.8% reduction in viscosity is possible by varying nanoparticle sizes. The current study proposes additional new findings on the nanofluids' usability.