Heterogeneous nucleation of argon vapor on the nanostructure surface with molecular dynamics simulation

The study of vapor condensation on surface has important engineering significance. The condensation nucleation process of vapor on substrates with different pillar structures is studied through molecular dynamic simulation. The condensation droplets on the pillar with various heights and solid fractions exhibit Wenzel state, Cassie state and the transformation from Wenzel state to Cassie state. The results show that the condensation efficiencies are correlated with the state of droplet and it is explained from the perspective of heat transfer. For the Wenzel state, the droplet fills the gap of pillar and the form of the heat conduction change with the growth of cluster. In the initial of condensation droplets, the heat conduction is similar with various heights of pillar. As the condensation droplets grow, the efficiency of heat conduction enhances with the increasing of height of pillar. For the Cassie state, the form of heat conduction is perpetual during the condensation process with the thermal resistance of the droplet dominated due to the droplets suspended on the pillar. The efficiency of heat transfer is insensitive to the height of pillar. The form of heat conduction for the transformation state transforms from Wenzel state to Cassie state leading to the reduction of condensation rate. The droplet formed in the Wenzel state has the higher transfer efficiency than the Cassie one.