Modeling of PEMFC Transients with Finite-Rate Phase-Transfer Processes

The dynamic performance of polymer electrolyte membrane fuel cells (PEMFCs) is of great interest for mobile applications such as in automobiles. In this study, a rigorous three-dimensional transient model has been developed through a comprehensive inclusion of various transport phenomena and phase-transfer processes. The finite-rate membrane sorption/desorption process and water condensation/evaporation process are essential for transient modeling of PEMFCs, yet they have been generally neglected in previous studies. A sinusoidal impedance approach is employed to identify the time scales for different dynamic transport processes. The dynamic response to changes in several operating conditions, such as voltage sweeping with different sweep rates, step changes in the cell voltage, relative humidity, inlet gas pressure, and stoichiometric ratio, has been investigated, and the results demonstrate qualitatively good agreement with experimental results.