Effects of temperature and particles volume concentration on the thermophysical properties and the rheological behavior of CuO/MgO/TiO2 aqueous ternary hybrid nanofluid

Abstract

In the present study, the impacts of nanoparticles volume concentration and temperature on the thermophysical properties and the rheological behavior of water-based CuO/MgO/TiO2 ternary hybrid nanofluids were elucidated. Five types of CuO/MgO/TiO2 aqueous THNFs (ternary hybrid nanofluids) including A (33.4 mass% CuO/33.3 mass% MgO/33.3 mass% TiO2), B (50 mass% CuO/25 mass% MgO/25 mass% TiO2), C (60 mass% CuO/30 mass% MgO/10 mass% TiO2), D (25 mass% CuO/50 mass% MgO/25 mass% TiO2) and E (25 mass% CuO/25 mass% MgO/50 mass% TiO2) were fabricated. All experiments were performed under the temperature range of 15–60 °C in the solid volume concentration range of 0.1–0.5%. The experimental results demonstrated that the rheological and the thermophysical properties of THNFs depend not only on the nanoparticles volume concentration, but also on the temperature of THNFs. All the THNFs demonstrated Newtonian behavior. The dynamic viscosity and the thermal conductivity of THNFs increased with enhancing solid particles volume concentration and temperature. The highest increment in thermal conductivity as compared to distilled water was obtained for the C type of THNFs at 0.5 solid vol% in 50 °C. The specific heat capacity of THNFs first decreased up to 35 °C and then increased with raising temperature. The highest reduction of specific heat capacity of THNFs was found for the C type of THNFs. The surface tension of B and C types of THNFs increased with the particles volume concentration enhancement. In the cases of low particles volume, the surface tension of THNFs was lower than that of the distilled water, for a concentration of the nanoparticles of 1.0%. Four new correlations were developed to predict the viscosity, thermal conductivity, specific heat capacity and density of the THNFs. All the proposed correlations had a satisfactory accuracy of ± 1%.