Effects of Gas Macromixing in Polymer Electrolyte Fuel Cell

For PEFCs' grand-scale commercialization, their performance should be further improved. The performance of PEFC is results of the distributions of local current density and materials concentration, especially oxygen and water. In addition, the in-plane transport of reactant gas in the gas diffusion layer (GDL), which is difficult to measure, affects the distribution of oxygen partial pressure and relative humidity (RH) by mixing the gas with different residence time. In this study, the PEFC was regarded as a reactor, the gas macromixing in which was evaluated by residence time distribution (RTD) in the perspective of chemical engineering. The cell performance with different active area and gas flow rate in parallel and serpentine gas channels was measured experimentally and predicted by the compartment models. According to the model, the gas macromixing in the 1 mm-manifold parallel channel is more obvious than that in the serpentine model, and has better performance at low oxygen conversion, since appropriate water humidification is beneficial to the cell performance. The results also indicate that the gas macromixing should be promoted to improve the water humidification and the cell performance at low oxygen conversion. The computationally inexpensive compartment model is potentially applicable for system simulator and design procedure.