Investigation of Nanoscale Droplet Evaporation by Molecular Dynamics Simulations

Abstract

Heat transfer by boiling is promising for future thermal management problems. The phase change during boiling condition is interrupted by a vapor layer forming between the liquid and solid, which is called as the Leidenfrost phenomena. Leidenfrost develops strongly depending on the solid/liquid coupling at the interface. For such a case, we studied evaporation behavior of water droplets at nanoscale under varying wetting conditions in order to characterize the Leidenfrost effects. While the experimental analysis is challenging, we employed Molecular Dynamics simulations of water droplets over silica surfaces to investigate Leidenfrost at nanoscale. As a continuation of our earlier work on size dependent influence of contact line pinning on wetting of nano-textured/patterned silica surfaces. Evaporation of the different size droplets were simulated over silica surfaces with different nanopatterns. We observed that the thermal transport at the solid-liquid interface showed strong dependence on surface wetting and Leidenfrost temperature. Specifically, a sudden increase in the interface thermal resistance was observed when the droplet temperature reached to the Leidenfrost point, and the heat transfer decreased significantly. Increasing the size of the surface structures pushed the Leidenfrost point to higher surface temperatures.