A re-optimized design of mesh-type transition zone for large-scale PEM fuel cells considering two-phase flow distribution

The flow distribution in the Flow Field Plate (FFP) has a significant impact on the performance and durability of large-scale Proton Exchange Membrane (PEM) fuel cells. Most of the existing studies focused only on gas-phase flow, while the actual cell operation is gas-liquid two-phase flow. In this study, numerical simulations of single- and two-phase flow distributions are performed for three-dimensional FFPs. The Coefficient of Variation (CV), defined as the ratio between the standard deviation and the mean of the velocities in channels, serves as the indicator of flow uniformity. Firstly, the differences between gas- and two-phase flow distribution characteristics of the FFP with the combined-mesh-type transition zone we previously constructed are elucidated. Secondly, a re-optimized layout with horizontal mesh apertures in the distribution zone and the addition of horizontal mesh in the collection zone is proposed. The design philosophy and methodology based on the coupled flow and resistance regulation mechanism are elucidated. The single- and two-phase CV values are further reduced by 41.25 % and 6.05 %, respectively. Thirdly, the re-optimized structure is applied to different FFP geometries, including smaller development spaces and larger cell areas, where the superior effects on flow distribution are validated.