Determination of Thermal Conductivity and Viscosity Values of Al2O3-MWCNT/Pure Water Hybrid Nanofluid

Abstract

When the studies on nanofluids in recent years are examined, it is seen that hybrid nanofluids are used to improve their thermophysical properties. The most important step in the comparison of hybrid nanofluids with single nanofluids and basic fluids (water, oil, ethylene glycol, etc.) is to determine their thermophysical properties. The aim of this study is to determine the thermal conductivity and viscosity values of Al2O3-MWCNT/Pure Water nanofluids with increasing volumetric ratio and temperature, finally compare the obtained values with the existing correlations. In the study, Al2O3– MWCNT/Pure Water hybrid nanofluids with 0.1%, 0.2% and 0.3% volumetric ratios were prepared by suspending Al2O3 and MWCNT nanoparticles in pure water at mixing ratios of 0:100%, 50:50% and 100:0%. Experimental results showed that both the thermal conductivity and viscosity of the prepared hybrid nanofluids increased with the nanoparticle volume concentration. It was determined that the thermal conductivity value of the hybrid nanofluid prepared at a 50:50 mixture ratio of 0.1% by volume was higher than the mono nanofluids. Compared to pure water, the highest thermal conductivity increase of 8.56% was obtained for 0.3% (0:100) Al2O3-MWCNT/Pure Water nanofluid at 50°C. The viscosity values increased with the increase of the volumetric ratio and the highest increase was determined as 54.73% for the 0.3% (5050) Al2O3-MWCNT/Pure Water hybrid nanofluid at 20°C compared to pure water. The maximum viscosity decrease that occurs when the temperature rises from 20°C to 50°C is 55.72% for the 0.3% (50-50) Al2O3-MWCNT/Pure Water hybrid nanofluid at 50°C. © 2022, Gumushane University. All rights reserved.