Three-Dimensional Performance Model For Oxygen Transport Membranes

Abstract

A three-dimensional (3D) finite element method (FEM) model that enables the performance simulation of mixed ionic-electronic conducting (MIEC) oxygen transport membranes (OTM) has been developed. In order to evaluate the influence of a porous functional layer on the membrane performance a numerical geometry generator was implemented that allows to create arbitrary porous microstructures. The 3D OTM model includes the spatially coupled physicochemical processes i) gas diffusion in the porous functional layer, ii) oxygen exchange at the feed-side between the gas phase and the MIEC material, iii) oxygen ion diffusion across the membrane, iv) oxygen excorporation at the permeate-side. The performed simulation carried out for La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) identified a surface exchange dominated regime for membrane thicknesses below 50 µm. While the application of a porous functional layer on the feed-side could only increase the permeation flux by around 26 %, the 3D OTM model demonstrates the significant improvement that can be achieved with a functional layer on the permeate-side of the membrane.

(Invited) MIEC Materials for Membrane Applications: Enhancing the Oxygen Transport

“…With the help of a 3D finite element method (FEM) OTM transport model (48) the interplay of transport parameters (D δ and k δ ) and functional-layer microstructure (thickness, porosity, particle sizes) can be readily assessed. The model calculates the flux through a dense MIEC membrane depending on materials properties, operating conditions and microstructure.…”