Numerical Simulation of Solid Oxide Fuel Cell for Impedance Analysis

摘要

The purpose of the current study is to model and simulate the impedance of a solid oxide fuel cell (SOFC) anode. The electrochemical impedance spectroscopy (EIS) is a powerful non-destructive method for obtaining the individual losses, characterization of materials, investigation of transport properties and the performance optimization of SOFCs. Efforts are devoted to develop tools that numerically evaluate the EIS experimental results. In this study a planar SOFC anode is modeled and the electrochemical spectra at the anode are obtained. The simulation is based on transient model of the anode when a periodic voltage is imposed. The model fully couples electrochemical kinetics with gas phase diffusion. The electrochemistry at the anode is modeled using Butler-Volmer equation, and gas diffusion model is based on the species equations. An in-house finite difference based code is used to solve the system of nonlinear equations. It is found that the Nyquist plot shows a capacitive semicircle which is identical to the gas conversion impedance as reported in literatures. A parametric study is also carried out by changing parameters, such as supplied gas compositions and cell dimensions, and the results are discussed. Furthermore, it is shown that the simulation results are in good agreement with published results.