Thermal Conductivity Enhancement for Aqueous Alumina Nano-Suspensions in the Presence of Surfactant

In this study, Al2O3-water nanofluids were synthesized, their thermal conductivity in water was investigated under different pH values and different sodium dodecylbenzenesulfonate (SDBS) concentrations. The thermal conductivity was measured by a Hot Disk Thermal Constants Analyzer. The results showed that the thermal conductivity enhancements of Al2O3-water nanofluids are highly dependent on the weight fraction of nanoparticles, pH values, and SDBS dispersant concentration of nano-suspensions. The Al2O3-water nanofluids with a small amount of Al2O3 have noticeably higher thermal conductivity than the base fluid without nanoparticles. For the Al2O3-H2O nanofluid with an optimal pH value and SDBS concentration, the thermal conductivity can be enhanced by more than 10% at a weight fraction of 0.0015. Therefore, the combined treatment with both the pH and chemical dispersant is recommended to improve the thermal conductivity for practical applications of nanofluid.