Pore-Level Multiphase Simulations of Realistic Distillation Membranes for Water Desalination.

Area of Science:

• Materials Science
• Chemical Engineering
• Fluid Dynamics

Background:

• Membrane distillation (MD) performance is limited by a lack of understanding of pore-level mechanisms.
• Improving MD efficiency requires detailed investigation of liquid-vapor interactions within membrane structures.

Purpose of the Study:

• To investigate pore-level fluid dynamics in membrane distillation using advanced simulation techniques.
• To analyze the impact of membrane geometry and surface properties on liquid entry pressure and droplet behavior.
• To determine the air-water interface characteristics in partially saturated membranes.

Main Methods:

• Utilized realistic 3D membrane geometries from ptychographic X-ray computed tomography (up to 0.5 billion voxels at 39nm resolution).
• Employed the D3Q27 lattice Boltzmann (LB) method with the Shan and Chen multi-phase model for pore-level simulations.
• Investigated liquid entry pressure, Wenzel and Cassie-Baxter states, and water-membrane contact surfaces.

Main Results:

• Quantified liquid entry pressure for various membrane samples.
• Analyzed the influence of micropillar structures on droplet states (Wenzel/Cassie-Baxter).
• Determined air-water interface characteristics, correlating droplet size and distribution with membrane porosity.

Conclusions:

• Lattice Boltzmann simulations provide crucial insights into pore-level phenomena in membrane distillation.
• Membrane geometry and surface characteristics significantly affect liquid entry and wetting behavior.
• Understanding the air-water interface is key to optimizing membrane performance and preventing pore wetting.