Promote anti- /de- frosting by suppressing directional ice bridging

Abstract

Condensation frost is one of the most common types of icing encountered in nature and industrial applications, while its accretion induces multiple non-negligible negative impacts. Many passive anti-/de- frosting approaches by tailoring surface topology and chemistry have been reported recently. To date, however, reliable engineered surfaced that can be compatible with heat exchangers from both mechanical and economic perspectives are limited. In this paper, we present a hierarchically structured surface that can profoundly reduce the frost coverage, and meanwhile promote the rapid removal of frost melts. This surface consists of microgroove pattern and nanoblade structure, where the former provides preferential sites for the growth of condensed droplets, and the latter promises a robust water repellent nature. During frosting, the ice phase spreads only among droplets on groove edges while condensed droplets in valleys are completely evaporated off, yielding a typical pattern that ice stripes distribute discretely in the dry background. During defrosting, frost melts coalesce into large droplets that spontaneously depart the substrate surface. Our results open up a new avenue for surface engineering, particularly on the design of economic and scalable anti-/de- frosting surfaces.