Influence of pH and SDBS on the Stability and Thermal Conductivity of Nanofluids

Aiming at the dispersion of nanoparticles which are regarded as the guide of heat transfer enhancement, we investigated the heat transfer enhancement of two water-based nanofluids, namely, water−Al 2 O 3 and water−Cu mixtures. The absorbency, ζ potential, and thermal conductivity of the nanofluids were measured under different pH values and different sodium dodecylbenzene sulfonate (SDBS) dispersant concentrations. The results showed that the stability and thermal conductivity of nanofluids were highly dependent on pH values and SDBS concentrations of nanosuspensions; an optimal pH value and optimal SDBS concentration can result in the highest stability and thermal conductivity of the nanofluids. Therefore, the combined treatment with both the pH and the chemical surfactant concentration was recommended to improve the stability and thermal conductivity for practical applications of nanofluid.