Numerical simulation of such a complex system as a fuel cell requires flexible software packages and powerful mathematical methods. We use a number of commercially available software tools (MATLAB, SIMULINK, STAR-CD, ...) as well as in-house software packages (DENIS). The latter allows the implementation of specialized algorithms, for example for the simulation of electrochemical impedance spectra.
A number of computational tools for the representation and interpretation of simulation results are developed and applied. Particularly useful is the so-called sensitivity analysis for the identification of rate-determining processes (Fig. 1). Other tools include fitting algorithms for parameter identification and model validation, as well as reaction and mass flow analyses.
Electrochemical impedance spectroscopy (EIS) has proven a powerful technique for the experimental characterization of fuel cells. The simulation of impedance spectra is one focus of our research activities. Here, we do not apply equivalent circuits for impedance interpretation. Instead, impedance is numerically calculated based on detailed electrochemical models, including elementary kinetic chemistry and gas-phase transport (Fig. 2).
|Fig. 1: Sensitivity analysis of a detailed electrochemical model of an SOFC anode.|
|Fig. 2: Simulated impedance spectra of convective and diffusive transport in the gas phase above a fuel cell anode for various inflow velocities v.|