Ultra-high fuel utilization in polymer electrolyte fuel cells part I: An experimental study

In this study, a high fuel utilization approach for polymer electrolyte fuel cells (PEFC) is proposed and studied experimentally. This approach uses an ultra-low hydrogen stoichiometry supply (i.e., xi(a) = 1.02) meanwhile sustaining stable cell performance. Systematic experiments showed the feasibility of high fuel utilization approach under different pressures and hydrogen/air inlet humidification conditions. It is indicated that the fuel cell is able to provide stable performance at a real fuel stoichiometry xi(a) = 1.02 under high-current density operation. For all the tests at xi(a)/xi(c) = 1.5/2.0 or 1.02/2.0, there exist unstable operation regimes typically in low power conditions. The instability as a result of flooding is affected mainly by air stoichiometry and less by fuel stoichiometry.