Voltage distribution analysis and non-uniformity assessment in a 100 cm2 PEM fuel cell stack

In this study, a comprehensive set of experimental tests were carried out to investigate individual cell voltage and temperature deviation under different operating conditions in a fuel cell stack. Five key operating conditions were considered: temperature, pressure, anode and cathode relative humidity, and cathode stoichiometry. Different configurations of reactant flow within the stack were also investigated. A 100 cm2 7-cell stack was used for the experiments, and voltage and temperature measurements were taken for each individual cell. Both ANOVA and range analysis method were used to evaluate the results. The findings showed that the performance of the external cells was consistently lower than that of the central ones since its temperature, the parameter that most affected performance, was also lower due to heat losses. Additionally, voltage deviation increased with temperature deviation. The study also revealed that stack performance was improved by an increase in temperature, pressure and cathode stoichiometry, whereas the effect of anode and cathode humidity was not so significant in the studied range. Furthermore, gravity played a clear role in water management, hindering the removal of condensed water for flow configurations where reactant gases were fed from the bottom interfaces of the stack.