PARAMETRIC MODELING OF THE PERFORMANCE OF A 5-KW PROTON-EXCHANGE MEMBRANE FUEL-CELL STACK

A parametric model predicting the performance of a solid polymer elect rolyte, proton-exchange membrane fuel cell has been developed using a combination of mechanistic and empirical modelling techniques. Mass-tr ansport properties, thermodynamic equilibrium potentials, activation o vervoltages, and internal resistance were defined by fundamental relat ions. But the mechanistic model, however, could not completely model f uel cell performance, since several simplifying approximations had bee n used to facilitate model development. Additionally, certain properti es likely to be observed in operational fuel cells, such as thermal gr adients, have not been considered. Nonetheless, the insights gained fr om the mechanistic assessment of fuel cell processes were found to giv e the resulting empirical model a firmer theoretical basis than many o f the models presently available in the literature. Correlation of the empirical model to actual experimental data was very good. The perfor mance of a Ballard Mark V 35-cell stack, using a Nafion(TM) electrolyt e membrane, and operating on inlet feeds of air (150% excess) and hydr ogen (15% excess) has been modelled parametrically, based on a model p reviously developed for a Ballard Mark IV single cell.