Motivated by the automotive industry’s requirements to better understand this dynamic behavior, in this talk we present our latest modeling efforts emphasizing the transient response of the cell. In particular, we present a fully coupled two-dimensional finite element model with two-phase flow and non-isothermal effects. The model resolves transport across various length scales, including the diffusion media and the catalyst layers, where a recently developed homogenous model is employed to account for the local oxygen transport resistance . Moreover, anisotropy in material properties is considered to model in-plane variations. Oxygen reduction reaction (ORR) is described using the modified double-trap model that captures doubling of the Tafel slope . ORR dependency on relative humidity is also taken into account [7, 8]. Values reported in the literature for time constants of membrane water sorption and desorption are discussed. Based on this discussion, a factor scaling the time constant of the original diffusion equation used for membrane water transport is introduced and its importance is discussed through transient modeling results.
In general, the model can be used to investigate the transient response of the fuel cell under various operating conditions. A steady state version of the model can help in making design decisions to improve cell performance. Finally, the model can serve as a benchmark to parameterize and validate more computationally efficient models that can be used for real-time applications.
Financial support for this work was provided by Ford Motor Company through the Ford University Alliance Program.
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