A computational investigation of high-flux, plate-and-frame membrane modules for industrial carbon capture

In this work, we study the application of membrane-based separation systems for carbon capture, considering plate-and-frame membrane modules. The successful deployment of membrane CO₂ capture systems relies on high-performing membranes, as well as on effective membrane modules that can fully exploit the developed membranes. A plate-and-frame membrane module is especially attractive for CO₂ capture from industrial flue gas, due to its reduced pressure drop compared to its counterparts such as spiral wound modules and hollow fiber modules. To design better plate-and-frame modules, we investigate their basic unit - a single membrane stack - through a combination of computational modeling and experimental investigations. The modeling approach is based on computational fluid dynamics (CFD) to represent the multiphysics problem, including the fluid flow and diffusion processes within the membrane stack. We use experimental data collected under different operating conditions to validate the CFD model. Numerical results suggest good agreement between experiments and model outputs for CO₂ recovery, CO₂ mole fractions in the retentate and permeate, and stage-cut. The CFD model is able to predict accurately the flow behavior, providing valuable insights into the effects of fluid dynamics on the mass transfer of CO₂. CFD models achieve high accuracy by capturing complex permeate-side flow patterns exhibiting a 4.5 % maximum relative error compared to experiments. Results suggest that deviations of 1D models, assuming ideal flow patterns, from the CFD increase as separation properties improve with material advancements, and can be as high as 21 % for some cases. We also carry out a sensitivity analysis to identify the effect of key parameters on the CO₂ recovery and the CO₂ purity of the outlet streams.