Thermophysical properties of Al2O3-CuO hybrid nanofluid at different nanoparticle mixture ratio: An experimental approach

The main objective of this research is to examine the effect of nanoparticle mixture ratio and nanofluid temperature on the thermal conductivity of Al2O3-CuO/water-EG hybrid nanofluid. The stable suspension of Al2O3-CuO hybrid nanofluid was prepared at four different nanoparticle mixture ratios of 20: 80,40:60, 50:50, and 60:40 at a volume concentration of 1.0%. The thermal conductivity and viscosity measurements were performed at a temperature range of 30 degrees C to 70 degrees C. Zeta potential and particle analyzer were used to evaluate the dispersion stability of the hybrid nanofluid and analyze the nanoparticle size distribution. In addition, TEM and XRD method were used for the morphological characterization of the Al2O3 -CuO nanoparticles. The highest thermal conductivity for Al2O3-CuO nanofluid was obtained for nanoparticle ratio of 60:40 with a maximum enhancement up to 1233% relative to the base fluid. Besides, the viscosity of hybrid nanofluid showed a decreasing trend with the increase in temperature. The crystallite sizes of Al2O3 and CuO nanoparticles calculated based on the XRD data noted to approximately 8 nm and 24 nm. respectively. The data from zeta potential analysis indicated that the Al2O3-CuO hybrid sample with 50:50 ratio has moderate dispersion stability. A new correlation has been proposed to predict the thermal conductivity of Al2O3-CuO hybrid nanofluid with an accuracy of 95%. The forced convection heat transfer experiment shows that Al2O3-CuO hybrid nanofluid exhibits a good thermal performance compared to the base fluid. (C) 2020 Elsevier B.V. All rights reserved.