The influence of particle size on the viscosity of water based ZnO nanofluid
Gökberk Yalçın, Semiha Öztuna, Ahmet Selim Dalkılıç, Somchai Wongwises
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.