Spatial Control of Frost Formation on Surfaces with Millimetric Serrated Features

TL;DR

This study investigates how millimetric serrated surface structures influence frost formation, revealing that frost initiates at peaks and is suppressed in valleys, with implications for designing durable icephobic surfaces.

Contribution

It introduces a novel approach using serrated surface features inspired by natural leaves to control frost growth and distribution, addressing durability issues of traditional icephobic coatings.

Findings

Frost initiates at peaks and is suppressed in valleys on serrated surfaces.

Frost growth is affected by humidity, wettability, and surface geometry.

Diffusion of water vapor critically influences frost pattern formation.

Abstract

Numerous studies have focused on a low surface energy coating and a micro/nanoscale surface texture to design functional surfaces that delay frost formation and reduce ice adhesion. However, the scientific challenges for in developing icephobic surfaces have not been fully addressed because of degradation such as mechanical wearing. Inspired by the suppressed frost formation on concave regions of natural leaves, here we report findings on the frosting process on hydrophobic surfaces with various serrated structures. Dropwise condensation, the first stage of frosting, is enhanced on the peaks and suppressed in the valleys when the serrated surface is exposed to humid air, causing frosting to initiate from the peak. The condensed droplets in the valley are then evaporated due to the different equilibrium vapor pressure of ice and water, resulting in a non-frost band on both hydrophobic and superhydrophilic surfaces. The frost growth is systematically studied by employing various levels of ambient humidity, surface wettability, and surface geometry. Numerical simulations show the critical role of diffusion of water vapor in the formation of the discontinuous frost pattern.