Effects of operating conditions on the performance uniformity of the proton-exchange membrane fuel cell stack.

[Display omitted] • Mechanism of performance uniformity of the PEMFC stack is explored. • Novel evaluation method for the performance uniformity is established. • Power density of the PEMFC achieves an improvement between 4.78% and 15.44%. • Performance uniformity can be increased about 29.95–66.94%. The performance uniformity of the proton-exchange membrane fuel cell (PEMFC) stack depends sensitively on the operating parameters. In this work, the dispersion of performance across the cells is explored through experiments and simulations, and the effects of operating conditions on the performance uniformity are evaluated using a novel criterion. According to the results, operating conditions such as stoichiometric ratio (SR), back pressure (P B), dew point temperature (T D), and heating temperature (T H) have a great influence on the performance uniformity and determine the content of liquid-saturated water and the uniformity of oxygen distribution at the catalytic layer (CL)/gas diffusion layer (GDL) interface of fuel cell. Further research shows that decreasing the content of liquid-saturated water and increasing the uniformity of oxygen distribution can improve the output performance stability, while increasing the oxygen content can improve the output performance of the PEMFC stack. What's more, when the stoichiometric ratio (SR), back pressure (P B), dew point temperature (T D), and heating temperature (T H) are 2.0, 3.0, 0.7 bar, 0.6 bar, 343 K, 333 K, and 348 K, respectively, the performance uniformity of the PEMFC stack achieves the best. [ABSTRACT FROM AUTHOR]