Prediction of electrochemical characteristics of practical-size solid oxide fuel cells based on database of unit cell performance

Abstract

A novel numerical methodology for predicting the electrochemical characteristics of a practical-size solid oxide fuel cell (SOFC) is proposed. The core idea is to divide the practical-size cell into independent one-dimensional (1D) unit cells and to evaluate the characteristics of the practical-size cell as an aggregation of the performance of local unit cells. The proposed methodology consists of two steps. The first is to construct a database of the electrochemical performance of the unit cells under a comprehensive range of operating conditions. For this purpose, a 1D numerical simulation model is developed and validated by comparing the predicted values with experimental data. It is confirmed that not only the current–voltage characteristics but also the impedance characteristics are accurately reproduced by the developed unit cell model. The second is to reproduce the performance of the practical-size cell using the constructed database. The cell is considered as an assembly of unit cells and the electrochemical performance of each unit cell is determined by referring to the constructed database. Subsequently, the macroscopic characteristics of the entire cell are evaluated by using the derived theoretical expressions correlating the macroscopic characteristics with the local electrochemical performance. The predicted cell characteristics fairly agree with the experimental data found in the literature. Since the macroscopic characteristics of the practical-size cell is evaluated with simple arithmetic expressions, the computational cost is significantly reduced, which realizes an exhaustive parametric study of the practical-size cell to identify the optimal operation conditions.