A detailed investigation on the thermo-physical and rheological behavior of MgO/TiO2 aqueous dual hybrid nanofluid

Experimental study of thermo-physical properties and rheological behavior of MgO-TiO2/DW (distilled water) nanofluids with the weight percent of 50:50,80:20,20:80, 60:40 and 40:60 are presented in this paper. Dual Hybrid Nanofluids (DHNFs) were prepared by suspending MgO and TiO2 nanoparticles in distilled water in the presence of Sodium Dodecyl Sulfate (SDS) as a surfactant. The temperature dependence of the properties in the range from 15 to 60 degrees C was measured. All experiments were fulfilled at different solid volume concentrations (0.1-0.5 vol%). The stability time of nanofluids was more than 3 days. The experimental results showed that the thermal conductivity of DHNFs strongly depended on solid volume concentration and rarely enhanced with enhancing temperature. The highest enhancement of thermal conductivity of DHNFs related to solid volume concentration was found to be 21.8% for 80 wt% MgO-20 wt% TiO2 equivalent to 0.3 solid vol% at 60 degrees C. The dynamic viscosity of DHNFs increased with enhancing solid volume concentration and reduced with enhancing temperature. The rheological behavior of MgO-TiO2/DW DHNFs was Newtonian in all laboratory conditions. The specific heat capacity of DHNFs (80 wt% MgO-20 wt%TiO2) decreased by 1.08% with a solid volume concentration of 0.5%. The temperature had not much impact on density enhancement. Additionally, 3 empirical correlations were presented to predict the aforementioned properties of DHNFs and the calculated results of which are in good agreement with the experimental data. (C) 2019 Elsevier B.V. All rights reserved.