Abstract
Modeling of proton exchange membrane (PEM) fuel cells is attracting more attention as fuel cell technology continues to develop. In this study, we considered a hybrid model that combines an agglomerate model based on the agglomeration of catalyst particles and the coverage-dependent kinetic equation of platinum oxide for ORR, and another 3D numerical model of a PEM fuel cell based on computational fluid dynamics (CFD). The obtained results from our developed models were validated with experimental results from literature. In fact, we investigated the effects of changing the agglomerate radius (Ragg) , the ionomer volume fraction within the agglomerate (Yi,agg), the effective agglomerate surface area (Ai,agg) , the distribution of the gases and the temperature on the cell performances. The results revealed that the cell performances are strongly influenced by changing Ragg and Yi,agg for medium and high current densities: The activation loss increases with increasing Ragg and decreasing Yi,agg . Also, Ai,agg increases with decreasing Ragg and increasing Yi,agg . In addition, the PEM fuel cell's power output is significantly enhanced when Ragg is decreased and Yi,agg is increased, the optimal power being obtained for values of Ragg = 100nm and Yi,agg = 0.6. The numerical results also showed that decreasing the output voltage from 0.95V to 0.35V can accelerate the electrochemical reaction process.