Stabilize Cassie state and promote frequent jumping of condensed droplets for high-performance anti-frosting

Frost accretion, characterized by sequential vapor-liquid-solid phase changes, is undesirable in diverse industrial fields by virtue of heat transfer deterioration, machinery breakdown or even disasters. Such phenomenon lies in the complex and dynamic interactions between vapor/liquid and surfaces, in which tailoring the condensation dynamics, especially using superhydrophobic surfaces, holds great promise to dictate the spatially hysteretic frosting dynamics. However, previous studies have overlooked that to what extent the fusion of wetting state and jumping frequency of condensed droplets on superhydrophobic surfaces is favorable for anti-frosting. Herein, we propose a design of nanowire-cluster (NC) superhydrophobic surface that provides stabilized Cassie state and frequent self-jumping during the droplet lifecycle, enabling highly prolonged frost occurrence as well as frost propagation. With merits in desirable condensation dynamics, a NC surface with microgroove vertex angle of 30°and solid-liquid fraction of 31% presents enlarged droplet spacing and reduced mean droplet size, which are jointly responsible for hindering in inter-droplet ice bridge and droplet freezing. As a result, it delays the growth of frost by about a factor of 8 and 3 compared to its counterpart with either Cassie state or droplet jumping ability alone. In particular, the overall frost-free and frost-propagation duration can reach remarkable 200 min at a surface temperature of -8 ? and RH of 50%.