ISSN オンライン: 2688-7231
ISBN 印刷: 978-1-56700-497-7 (Flash Drive)
ISBN オンライン: 978-1-56700-496-0
Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019)
Temperature Dependent Rheological Behavior of Zinc Oxide Based Water Nanofluid
Nanofluids are stably dispersed suspensions of nanoparticles in the base fluids. Researchers have used surfactants, pH variations in the base fluids and variations of sonication time to enhance particle suspension stability. The dispersion of high thermal conductivity nanoparticles enhances the overall thermal conductivity of the nanofluids. The particulate suspension also affects the rheological properties of the fluid. In the present work, zinc oxide nanoparticles were dispersed in water via two-step method using ultra sonication. The particles used are in the size range of 30-50 nm. Particle morphology and chemical purity were assured by FESEM and EDAX analyses. The nanoparticles were used with the concentrations varying from 0.01wt. % to 1wt.% in the fluid. Zeta potential was employed to assure dispersion stability. Thermal conductivity analysis and rheology analysis were done in temperature range of 30°C to 90°C. Zinc oxide-water based nanofluids showed an enhancement of 15% in thermal conductivity at 1 wt. %. Nanofluids presented consistent enhancement in viscosity with increasing concentration. The rheology analysis also showed the slightly dilatant nature of nanofluids at low temperatures and low shear rates. With the increase of shear rates and temperature, the de-agglomeration of particle occurs along with increased Brownian motion which leads to slightly Newtonian nature of nanofluids.