An accurate way to determine the ionic conductivity of mixed ionic-electronic conducting (MIEC) ceramics

摘要

Measuring oxygen transport through dense, mixed ion electron conducting, ceramic membranes is usually performed in a lab-scale permeation set-up where feed and sweep gas are directly flushed to the membrane surface. Due to concentration gradients, the oxygen partial pressure (P-O2) measured at the outlet is not the same as on the membrane surface, leading to inaccurate calculations of the oxygen ionic conductivity (sigma(ion)) of the membrane. A computational fluid dynamics (CFD) model is developed to determine the exact P-O2 on the membrane surface. With this model, oxygen ionic conductivity of a model membrane, SrCo0.8Fe0.2O3-delta, is calculated. By comparing sigma(ion), based on perfect gas mixing with values based on the CFD model, it is found that the former one is overestimated by similar to 50-180% in the temperature and P-O2, range regarded. In addition, the influence of parameters, like type and flow rate of the sweep gas, is studied. (C) 2015 Elsevier Ltd. All rights reserved.