Lattice Boltzmann simulation of condensation on self-cleaning porous membrane

Self-cleaning porous membrane can serve as condensing surface for its capacity of transporting condensate to the back through the pores thus keeping the surface clean during the whole condensing period. However, the three-dimensional (3D) condensate behaviors including the initial nucleation, growth and permeation in the porous structures have seldom been clarified comprehensively. In this work, the 3D pseudopotential LB model with a phase change model are employed, and the condensation process inside the porous membrane with various porosity, wettability, additional external force and section geometric configurations are investigated. It's found that with the increase of porosity, surface hydrophobicity and additional external force, more rapid penetration of condensate in the porous media and correspondingly faster removal rate of liquid can be obtained, and the subsequent vapor condensation is enhanced. But the nucleation time gets longer with high porosity and surface hydrophobicity. The additional external force has little effect on the nucleation time. Larger porosity and lower flow resistance inside the straight channel lead to higher condensation rate at the initial stage of condensation, while the porous structure with distorted pores with the same porosity contributes to improve the total condensation amount. This work helps to select the porous membranes with different porosity, wettability or pore scale geometric characteristic and external field for different condensation conditions in specific applications.