Investigation on the growth characteristics of condensed droplet clusters on superhydrophobic surface within humid air

Abstract

The dropwise condensation with supercooling is usually one of the processes of frosting on superhydrophobic surfaces within humid air. Investigation on the growth characteristics of droplet clusters before freezing helps to reveal the frost suppression mechanism of superhydrophobic surfaces and provides theoretical support for development of new defrosting methods. For the growth process of droplet clusters, the growth, deformation and jumping models of droplets are established, and the dynamic simulation algorithm for the clusters’ growth is developed. The models and simulations are verified through visual experiments. On that basis, the influencing mechanism of surface wettability, air humidity, substrate temperature on droplet growth and coalescence behavior is studied, and the growth of droplet clusters under typical frosting conditions is simulated. The results show that the growth rate of an individual droplet shows lower sensibility to substrate wettability and temperature compared with humidity, but the substrate wettability affects the coalescence behavior and then has a significant influence on the evolution of cluster parameters. The characteristic size of droplet clusters oscillates for the occurrence of jumping and regrowth in the condensation, and tends to be stable in the process approaching to equilibrium state.