Influence of nanoparticles size, per cent mass ratio, and temperature on the thermal properties of water-based MgO–ZnO nanofluid: an experimental approach.

This paper experiments the trio influence of nanoparticles size (NS), per cent mass ratio (PWR), and temperature (T) on the thermal properties of MgO–ZnO/deionised water (DIW) nanofluids. MgO nanoparticles (20 nm and 100 nm) were hybridised with ZnO nanoparticles (20 nm) and suspended in DIW to formulate 0.1 vol% hybrid nanofluids at PWRs of 20:80, 40:60, 60:40, and 80:20 (MgO/ZnO). The pH, electrical conductivity (σ), viscosity (μ), and thermal conductivity (κ) of the hybrid nanofluids were experimentally determined at temperatures of 20–50 °C. The stability was monitored, while the morphology was examined using standard instruments. Findings showed that the suspension of the hybrid nanoparticles enhanced the pH and thermal properties of DIW. The hybrid nanofluids with 100 nm-MgO nanoparticles were observed to possess slightly higher values of pH, σ, and μ than those with 20 nm-MgO nanoparticles except for κ. An increase in temperature augmented κ and σ of MgO–ZnO/DIW nanofluids, while it detracted pH and μ. Maximum enhancements of 453.70–550.62% (40:60), 14.95–22.33% (40:60), and 8.29–17.46% (60:40) were evaluated for σ, κ, and μ, respectively. The influence of PWR, NS, and temperature on the σ, κ, μ, and pH of the hybrid nanofluids was in the order of PWR > NS > T, NS > PWR > T, T > NS > PWR, and T > NS > PWR, respectively. Subject to the experimental data obtained, correlations were developed for each hybrid nanofluid and thermal property as a function of temperature. The MgO–ZnO/DIW nanofluids with a 40:60 PWR appeared to be the best in terms of heat transfer capability. [ABSTRACT FROM AUTHOR]