Study of jumping water droplets on superhydrophobic surfaces with electric fields

Abstract

© 2017 Macro-sized droplets adhering to non-wetting surfaces, a phenomenon referred to as progressive flooding, is one of the major problematic issues found on a superhydrophobic condenser, which reduces the heat and mass transfer performance. Utilization of an electric field on superhydrophobic surfaces can potentially address this problem. In this study, a water droplet is placed on a superhydrophobic plate which is in parallel to another plate. A positive electrode and a ground line are connected to the bottom plate and the top plate, respectively. The droplet motion is recorded by a high-speed camera and analyzed in sequential frames. This work aims to investigate the electrical voltage threshold, the electric field threshold and the droplet charge required to remove a macro-sized droplet from a superhydrophobic surface. The results show that with an increase in gap width, both the electrical voltage threshold and the electric field threshold increase, while the droplet charge decreases. Additionally, the results of this study also reveal a constant electrostatic force acting on droplets in the air and the maximum electrostatic force acting on droplets on the superhydrophobic surface regardless of the gap width and of applied electric field intensity. This work can offer a platform for improving the performance of self-cleaning surfaces, thermal diodes/switches and anti-icing surfaces.