Dominance of cohesion of EG-water molecules over Van der Waals force between SiO2-ZnO nanoparticles in the liquid interface

Abstract

The effects of loading SiO2-ZnO nanoparticles on EG-water surface tension were examined in this study. Using SITA dynotester, surface tension was measured at 25–50°C. The dispersed nanoparticles reduce the density of liquid molecules at the interface and weaken the cohesion which in turn attenuate the surface tension. On the other hand, the strong force of Van der Waals between nanoparticles strengthens the surface tension. Laboratory results showed that the effects of the reduction in cohesive force could not compensate by the Van der Waals force which consequently the EG-water surface tension reduced up to 13.2%.For the base fluid, the sensitivity of surface tension to the temperature was 0.1233 mN/m°C, while this figure for the nanofluid at 0.1 and 2 vol% was 0.0952 and 0.0566 mN/m°C, respectively. Therefore, it is claimed that the presence of nanoparticles decreased surface tension sensitivity to temperature. Finally, a correlation-based on the regression technique was developed by which the nanofluid surface tension behavior navigated with acceptable accuracy.