PERFORMANCE MODELING OF THE BALLARD-MARK-IV SOLD POLYMER ELECTROLYTE FUEL-CELL .2. EMPIRICAL-MODEL DEVELOPMENT

A parametric model predicting the performance of a solid polymer elect rolyte, proton exchange membrane (PEM) fuel cell has been developed us ing a combination of mechanistic and empirical modeling techniques. Th is paper details the empirical analysis which yielded the parametric c oefficients employed in the model. A 28 run experiment covering a rang e of operating currents (50 to 300 ASF), temperatures (328 to 358 K), oxygen partial pressures (0.6 to 3.1 atm abs.) and hydrogen partial pr essures (2.0 to 3.1 atm abs.) was conducted. Parametric equations for the activation overvoltage and the internal resistance of the fuel cel l were obtained from linear regression. The factors to be employed in the linear regression had been previously determined through a mechani stic analysis of fuel cell processes. Activation overvoltage was model ed as a function of the operating temperature, the product of operatin g temperature, and the logarithm of the operating current, and the pro duct of operating temperature and the logarithm of the oxygen concentr ation at the catalyst reaction sites. The internal resistance of the f uel cell was modeled as a function of the operating temperature and th e current. Correlation of the empirical model to experimental data was very good. It is anticipated that the mechanistic validity yielded by the coupling of mechanistic and empirical modeling techniques will al so allow for accurate predictive capabilities outside of the experimen tal range.