Effects of Concentration and Surfactant on the Dynamics of SiO₂ Nanodroplets During Evaporation

As a novel functional fluid, silicon dioxide (SiO₂) nanofluid has attracted growing attention due to the performance limitations of conventional fluids (e.g., water and oil) in thermal conduction, lubrication, and other applications. However, the impact behaviors and underlying mechanisms of SiO₂ nanofluid droplets on high-temperature surfaces remain poorly understood. This study employs experimental approaches to investigate the evaporation characteristics of SiO₂ nanofluid droplets with different concentrations, both in the presence and absence of surfactants. Additionally, the dynamic impact behaviors of these droplets on 7050 aluminum alloy plates at the Leidenfrost temperature are explored. The results demonstrate that higher concentration of SiO₂ nanoparticles accelerates the evaporation kinetics of the solution. The addition of sodium dodecyl sulfate (SDS) surfactant reduces the surface tension of the solution, thereby promoting the evaporation process. Moreover, SiO₂ nanofluid solutions with SDS exhibit a lower Leidenfrost temperature compared to those without SDS. The dynamic processes of SiO₂ nanofluid droplet impact at the Leidenfrost temperature involve the following stages, which are initial deposition, radial spreading, axial retraction, first rebound, secondary contact, sustained bouncing, and eventual stable evaporation. This study is conducive to a deeper understanding of the evaporation characteristics and impact dynamics of SiO₂ nanofluids under specific conditions. And it can provide a theoretical basis for their practical application in related engineering fields such as heat transfer and cooling systems.