Tunable self-jumping of melting frost on macro-patterned anisotropic superhydrophobic surfaces

Controllable fast self-removal of frost pieces from surfaces can effectively reduce energy consumption and residual droplets during defrosting. In this work, a tuning strategy of melting frost directional self-jumping on regular macro-patterned anisotropic superhydrophobic surface (MASS) was proposed. Under high-rate cooling condition, patterned frost on MASS with significantly different thickness distribution was observed, due to the water vapor gradient in and out of the deep grooves. During defrosting process, L-shaped melting frost on MASS shrank independently with two arms retracting inward, which further caused the melting frost's centroid/mass center to shift out of the pillar top. Partial contact with pillar tops and circular fillet introduced directional lifting force and enabled the directional self-jumping of the melting frost. Influencing factors on directional self-jumping of melting frost on MASS were also discussed. Utilizing macro-patterned anisotropic structure, the frost splitting process and its jumping direction were both tuned, which could promote the self-jumping of melting frost and thus improve the efficiency of defrosting.