PERFORMANCE MODELING AND OPTIMIZATION OF A POLYMER ELECTROLYTE MEMBRANE FUEL CELL UNDER DEAD-ENDED ANODE CONDITIONS
The hydrogen utilization and energy efficiency of a polymer electrolyte membrane fuel cell (PEMFC) with a dead-ended anode can be highly improved with the working conditions approximately designed and the influence of water flooding and nitrogen crossover fully considered. In the present paper, a comprehensive numerical model for a PEMFC with dead-ended anode, together with a newly proposed agglomerate model, has been developed, which considers the conversions among three different phases of water (namely water vapor, liquid water and membrane water). Both the performance degradation and performance recovery of a PEMFC under different working conditions have been demonstrated. Several optimization strategies in relation to the hydrogen utilization and the energy efficiency have been carried out. The results show that the accumulation of the nitrogen other than the water in anode electrolyte dominates the performance drop when a PEMFC operates in DEA condition and it needs a longer time to recover the performance when operating under a lower current density, resulting in lower hydrogen utilization. The mass transfer rate of nitrogen in the membrane is sensitive to the performance degradation of a PEMFC greatly, and the hydrogen utilization can reach as high as 92% when the diffusivity of nitrogen decreases to the order of 10-17 m2 s-1.