Characterization of oxygen transport phenomena on BSCF membranes assisted by fluid dynamic simulations including surface exchange

The influence of fluid dynamic conditions on the oxygen transport through mixed ionic-electronic membranes was studied experimentally and numerically. A set of permeation experiments was performed in a wide range of operating conditions combining temperature, driving force and flow rate of air feed and sweep streams. A computational model was built and enabled to systematically evaluate the effect of the fluid dynamic conditions on O2 separation process. This model includes the surface resistance (gas exchange kinetics) and bulk oxygen-ion diffusion. The experimental set was used to obtain the model parameters by following a two-step fitting procedure: a first fitting of a simplified one-dimensional model using genetic algorithms and a subsequent refining of the parameters using the complete model implemented in COMSOL Multiphysics. The high-accuracy model allowed characterizing the O2 transport phenomena and understanding the different factors governing the overall process, e.g. by using different membrane thicknesses, sweep gases or vacuum. Simulations of the fitted model revealed the importance of the sweep effect in the O2 transport across the membrane and enabled to establish rules for both design of permeation experiments and up-scaling.This work was financially supported by Spanish Government (Grants SEV-2016-0683 and RTI2018-102161) and Generalitat Valenciana (PROMETEO/2018/006)