Abstract
One of the essential specifications of nanofluids is the rheological behavior that has a significant effect on the system's performance. The primary objective of the present study is to investigate the rheological behavior and dynamic viscosity of the CuO-TiO2/water hybrid nanofluid. First of all, the chemical, atomic, and surface structures of the CuO and TiO2 nanoparticles were examined using X-ray diffraction, Fourier-Transform Infrared Spectroscopy, and Field Emission Scanning Electron Microscopy tests. Then, the two-step method was employed to prepare the needed samples. At the next step, the Dynamic Light Scattering test was used to examine the stability of the nanofluid. Furthermore, dynamic viscosity was measured in the different temperatures, ranging from 25 to 55 degrees C, and solid concentrations, ranging from 0.1 to 1 vol%. Moreover, the effect of shear rate on the rheological properties of the hybrid nanofluid was investigated. The results revealed that the prepared nanofluid is a Newtonian fluid. The results of dynamic viscosity measurements indicated that the maximum dynamic viscosity is at the solid concentration of 1 vol%, and a temperature of 25 degrees C. Finally, based on the obtained results, it can be said that considering different cost-benefit analyses, including high stability and low production cost, the studied nanofluids have a high quality and can be considered as an appropriate alternative for replacing the water-based fluid. (C) 2020 Elsevier B.V. All rights reserved.