Influence of flow maldistribution on the pressure drop and water condensation in a 100 kw PEM fuel cell stack

The Proton Exchange Membrane (PEM) fuel cell has been investigated for a long time because it has a high power density, low emission, wide choice of fuel sources, etc. However, the performance of a stack of PEM cells degrades with respect to that of a single cell. This is mainly due to the introduction of the manifold in which supplies the reactants to individual cells. The manifold can induce an additional pressure drop and a flow maldistribution. Therefore, it is critical to consider the interaction between the design of the manifold and the flow maldistribution. In this study, the sensitivity of the friction factor in the individual cells to the flow maldistribution and the interaction between the flow maldistribution and water condensation are discussed. As a result, it is found that the friction factors in the individual cells strongly influences the flow maldistribution especially when the flow in the unit cell is changed from laminar flow to turbulent. Large flow maldistributions induce the large pressure drops. As a result, water condensation can be little. However, it also induces a degradation in stack performance. A bipolar plate with a low number of flow channels can improve the flow maldistribution and water condensation in the unit cell although at the expense of a large pressure drop.