Numerical modeling of hydrogen permeation in chemical potential gradients

Abstract

A point defect model was used to describe the functional dependence of defect species in SrCe 0.95Y 0.05O 3− d on hydrogen, water vapor, and oxygen partial pressure. Concentrations of each defect were simulated with a C programming code. The mobilities of protons, oxygen ions, and electrons were evaluated from partial conductivities. Hydrogen permeation equations derived from chemical diffusion theory were solved by a numerical modeling method. Accurate predictions of the hydrogen permeation flux were possible only when the functional dependence of ionic/electronic conductivity on both hydrogen and oxygen partial pressure was known. The dependence of hydrogen permeation flux on hydrogen potential difference agrees with the P H 2 dependence of electronic conductivity. Hydrogen permeation flux calculated for 1 mm SrCe 0.95Y 0.05O 3− d was ≈1.50×10 −9 mol/cm 2 s under Δ P H 2 (=10 −7–1 atm), P O 2 (=10 −24–10 −12 atm) with the same P H 2O (=0.03 atm) on both sides at 973 K.