Droplets Impacting on Superheated Surfaces with Asymmetric Re-Entrant Microgrooves.

Abstract

Impacting droplets on hot solid surfaces is a widely used method for thermal management across various applications. Efficient heat transfer relies on the rapid detachment and directional shedding of these impacting droplets. Additionally, suppressing the Leidenfrost effect is crucial. However, there are currently no engineered surfaces that can simultaneously achieve reduced contact time, directional droplet shedding, and Leidenfrost suppression at high temperatures. This work introduces a novel type of surface with asymmetric re-entrant microgrooves (ARG surfaces) to address this challenge. ARG surfaces demonstrate Leidenfrost points (LFPs) as high as 725 °C and contact times lower than the theoretical limit at temperatures ranging from 350 to 650 °C. Additionally, they exhibit superior droplet centroid velocities and non-dimensional displacement factors. A theoretical model is also developed to predict the LFPs of these surfaces. Furthermore, temperature profiles of plain Si and ARG surfaces upon droplet impact confirm the superior cooling performance of ARG surfaces compared to plain Si. These results highlight the potential of ARG surfaces for achieving efficient cooling in diverse high-temperature applications.