Performance modeling of the Ballard Mark IV solid polymer electrolyte fuel cell

Abstract

A parametr ic mode l predicting the per formance of a solid po lymer electrolyte, proton exchange membrane (PEM) fuel cell has been developed using a combinat ion of mechanist ic and empirical model ing techniques. This paper details the empirical analysis wh ich yielded the parametr ic coefficients employed in the model. A 28 run exper iment covering a range of operating currents (50 to 300 ASF), temperatures (328 to 358 K), oxygen partial pressures (0.6 to 3.1 a tm abs.) and hydrogen partial pressures (2.0 to 3.1 a im abs.) was conducted. Parametr ic equations for the activation overvoltage and the internal resistance of the fuel cell were obtained f rom linear regression. The factors to be employed in the linear regression had been previously determined through a mechanist ic analysis of fuel cell processes. Activation overvoltage was mode led as a function of the operating temperature, the product of operating temperature, and the logarithm of the operating current, and the product of operating temperature and the logarithm of the oxygen concentration at the catalyst reaction sites. The internal resistance of the fuel cell was mode led as a function of the operating temperature and the current. Correlation of the empirical mode l to exper imental data was very good. It is anticipated that the mechanist ic validity yielded by the coupling of mechanist ic and empirical mode l ing techniques will also al low for accurate predictive capabil-ities outside of the experimental range. A mechanist ic mode l defining the factors most likely to influence fuel cell per fo rmance has been described previ-ously. I'2 The per formance of a fuel cell (output voltage) was defined as a function of the thermodynamic potential, the activation overvoltage, and the ohmic overvoltage, with mass transport losses being incorporated in each of the three terms V = E + ~ot + ~lohm ~ [1] The thermodynamic potential E was defined via a Nernst equat ion a