CFD analysis of a novel modular manifold with multi-stage channels for uniform air distribution in a fuel cell stack

Multiple fuel cells are generally connected in series or in parallel to supply a sufficient power output. Uniform distribution of hydrogen and air supplied to each individual fuel cell is a critical challenge, because the performance of a stack is limited by the single cell which receives the minimum amount of reactants. Various manifolds have been investigated in order to improve the flow distribution uniformity between individual fuel cells in a stack. However, a satisfactory uniformity is hard to obtain, and the existed manifolds are difficult to scale up. Therefore, a tree-type modular manifold is designed and optimized in the present study. Two different channel dimensions are compared regard to air flow distribution uniformity and overall pressure loss. The effects of channel length and air flow rate on the uniformity and pressure drop are studied by CFD simulation. The results show that an air flow uniformity around 0.99, which is the highest value reported in the literature, can be achieved in a wide range of air flow rate for a single fuel cell. The scale-up method by integrating several modular manifolds with a customized manifold to distribute air for larger fuel cell stacks is also explained.