Characterizing the thermal transport and kinetics of droplet evaporation on a solid surface with hybrid wettability

Abstract

To investigate the kinetics and energy transport during droplet evaporation on a heterogeneous solid surface with hybrid wettability, a series of molecular simulations are conducted in this work. Results indicate that droplet evaporation with constant contact radius mode almost dominates the whole process. The depinning can be initiated when the droplet contact angle declines to the value at which the droplet is stable on a homogeneous hydrophilic surface. Most of the heat conducted from the hybrid solid surface is transferred along adsorption layer to contact line, while only a small part of the energy is transported to the bulk droplet. When the heterogeneous substrate temperature is >115 K, the heat flux transferred along the adsorption layer always decreases first and then increases as droplet volume decreases, otherwise, it gradually decreases. Increasing the substrate temperature not only increases the evaporation rate but also enlarges the proportion of heat flux transferred to the bulk droplet. The statistical number of atoms in the liquid N and evaporation time τ satisfy the relationship of N2/3∝τ on the hybrid wettability surface. The lifetime for droplets evaporating on a heterogeneous wettability surface is reduced by 50% compared to that on a homogeneous hydrophobic surface.