Fast-freezing behavior of water droplet on subcooled superhydrophobic surface in DC electrostatic field

Abstract

Water freezing in electrostatic field (EF) exists widely in industry and daily life. In this study, we visualized the freezing behavior of distilled droplet on the superhydrophobic aluminum-surface with varied surface temperatures and EF strengths. It is found that the presence of EF, either upward or downward, can promote the nucleation of water even on the superhydrophobic surfaces. Nucleation is more prominent in the upward EF than in the downward EF provided the same field strength. Stronger EF contributes to shorter freezing-delay time and thus accelerate the overall freezing, although the freezing time becomes longer in stronger EF. Particularly, the interflow of the freezing droplet in EFs was exploited by micro-particle image velocimetry (μPIV). The average velocity of the internal flow was observed to increase with larger EF, implying the intensified internal cooling of water. This work unravels the underlying mechanism of the accelerated freezing behavior of water droplet in EFs and provides new insights into the modern applications in anti-icing and refrigeration industry.