Performance Modeling of the Ballard Mark IV Solid Polymer Electrolyte Fuel Cell: I . Mechanistic Model Development

TLDR

The paper details the development of a mechanistic model for a solid polymer electrolyte fuel cell. The model incorporates mass transport via Stefan–Maxwell equations, thermodynamic potentials via the Nernst equation, activation overvoltages via a Tafel relation, internal resistances via the Nernst–Planck equation, and ohmic overvoltages via Ohm’s law. Although the mechanistic model alone cannot fully capture fuel cell performance due to simplifying assumptions and omitted thermal gradients, it provides a stronger theoretical foundation for the empirical model, which correlates very well with experimental data.

Abstract

A parametric model predicting the performance of a solid polymer electrolyte, proton exchange membrane (PEM) fuel cell has been developed using a combination of mechanistic and empirical modeling techniques. This paper details the mechanistic model development. Mass transport properties are considered in the mechanistic development via Stefan‐Maxwell equations. Thermodynamic equilibrium potentials are defined using the Nernst equation. Activation overvoltages are defined via a Tafel equation, and internal resistances are defined via the Nernst‐Planck equation, leading to a definition of ohmic overvoltage via an Ohm's law equation. The mechanistic model cannot adequately model fuel cell performance, since several simplifying approximations have been used in order to facilitate model development. Additionally, certain properties likely to be observed in operational fuel cells, such as thermal gradients, have not been considered. Nonetheless, the insights gained from the mechanistic assessment of fuel cell processes were found to give the resulting empirical model a firmer theoretical basis than many of the models presently available in the literature. Correlation of the empirical model to actual experimental data was very good.