Simulation of substrate cooling during evaporation of pure vapor from the surface of a thin liquid film and droplets

A numerical study of the process of cooling the substrate under the conditions of evaporation of pure vapor from the surface of the film and a droplet of liquid was carried out. The lattice Boltzmann method was used for modeling of such a two-phase system, taking into account the thermal conductivity of the substance and evaporation. The van der Waals equation of state was used, which describes the liquid-vapor phase transition. A new method for setting the boundary conditions on a flat surface for modeling the contact wetting angles in the lattice Boltzmann method is proposed. During evaporation and condensation, the latent heat of the phase transition was taken into account. It is shown that the process depends on the film thickness and the rate of vapor removal from its surface. The cases of forced outflow of vapor, as well as the method of vapor condensation on a cooled condenser, are considered. It is shown that the heat flux from the substrate increases sharply in the vicinity of the droplet contact lines. A comparison is made of the heat fluxes during the evaporation of a film and droplets on a substrate with different wettability.