A fast and scalable mesh generation method of densely packed hollow fibers for membrane separations: Application to direct contact membrane distillation

Abstract

Modeling research on membrane distillation requires simulations of coupled momentum, mass, and heat transfer phenomena. Hollow fiber modules are preferred in industrial applications due to their high packing ratio, resulting in the number of fibers on the order of O(102−103) packed in a vessel. In hollow fiber membrane distillation processes, computational fluid dynamics (CFD) simulations of multi-physics require high-quality meshes for accurate calculations. Mesh interfaces between two different phase regions should conform to satisfy continuity conditions of coupled momentum, heat, and mass transfer. Due to the distinct geometric characteristics of HF packing structures, a scalable meshing method is of great necessity but has not been actively researched. This work developed a numerical method to generate hexagonally packed structures of many fibers by forming a hexagonal unit-cell, consisting of the lumen, membrane, and shell regions. Individual cells are made by duplicating a seed cell and packed to create a self-similar, hexagonal packing of hollow fiber membranes for multi-physics CFD simulations. A new theoretical approach was developed to represent the effusion-like convective mass transfer as conductive heat transfer, and our CFD results were in good agreement with experimental observations. Theoretical methods and numerical algorithms developed in this study can contribute to the improved scalability of CFD simulations from lab-scale modules to pilot-scale systems.