Effects of Sonication Period on Colloidal Stability and Thermal Conductivity of SiO2–Water Nanofluid: An Experimental Investigation

The objective of the present work is to analyze the consequences of the sonication period on the colloidal stability and thermal conductivity of SiO2–water nanofluid. Ultrasonication assisted two-step method was applied to prepare SiO2–water nanofluid at two different concentrations of 0.5 and 1 wt% without any surfactant. The sonication period varied from 1 to 3 h. Particle size was analysed by direct light scattering (DLS). Zeta potential analysis and light absorbance test were performed to check the colloidal stability of nanofluids. The thermal conductivity of nanofluid was measured over the temperature range of 25–60 °C. The obtained results indicate that increasing sonication time is crucial for the enhacement in stability and thermal conductivity of nanofluid. With increasing temperature, the thermal conductivity of nanofluids also increased. Moreover, at lower temperature, sonication plays a dominant role on thermal conductivity enhacement in nanofluids. The investigation concludes that a minimum 2.5 h of sonication is required for the better performance of nanofluids.