Dynamics and Mechanisms of Transition Regimes to Leidenfrost State on Micro-Fabricated Surfaces

A drop gently placed on a highly superheated surface can last for long time, running amok in different directions as it remains separated from the substrate by a vapor cushion formed due its own rapid evaporation. This regime referred to as Leidenfrost state is of great practical importance to industrial applications such as power plants, electronics cooling and boilers. Although a general trend for LFP on microstructured surfaces has previously been reported, a thorough investigation of a cross-over from transition boiling regimes to Leidenfrost state on such surfaces has not been investigated in detail. Herein, the authors discuss the role of nano/micro and hierarchical structures in controlling the Leidenfrost behavior of drops across wide temperature ranges. Precisely controlled features were obtained on substrates using photolithography techniques. high-speed imaging is used to recognize the transient boiling and rebound behavior. Theoretical and experimental analyses were conducted to map the transition regimes with respect to the surface topology. Dynamic effects due to droplet size and impact velocity were considered to elaborate on the nature and mechanism of transition boiling and Leidenfrost state.