Vacuum membrane distillation: Three-dimensional lattice Boltzmann method insights into pore geometry, wettability, and thermal driving force

Membrane distillation (MD) presents distinct advantages for freshwater production in water-scarce regions. Accurate simulation of vapor–liquid flow within membrane pores is crucial for optimizing MD efficiency; however, it is hindered by complex pore geometries and multi-scale effects. This study implements a three-dimensional (3D) simulation framework that integrates a curved boundary interpolation algorithm with a mass conservation correction scheme. Based on a 3D lattice Boltzmann method combined with a chemical potential-regulated multiphase flow theory and a hybrid thermal evolution equation, a fully 3D flow domain covering the feed, membrane, and permeate sides is established to overcome the geometric simplifications inherent in conventional two-dimensional approaches. The effects of porosity, tortuosity, and transmembrane temperature difference on water flux are systematically analyzed. The simulated water flux demonstrates excellent agreement with experimental data, yielding an average relative error of only 4.89% across the temperature range of 40–90 °C. Furthermore, a critical threshold for the membrane contact angle is identified, below which undesirable liquid intrusion into the permeate side occurs. This study provides quantitative insights into vapor–liquid flow in curved pores and offers theoretical guidance for MD membrane optimization and operational control, supporting its scaling-up in water-scarce areas.