Numerical Investigation of Flowfield in PEM Fuel Cell Stack Headers

Abstract

This study addresses the factor often overlooked in analysis of fuel cell stack performance, namely the influence of the disturbances in the flowfields in the stack inflow and outflow headers. The flowfield in the header, formed by a superposition of numerous secondary in/outflows, has a complex and fundamentally unsteady nature, which has been shown by previous studies to result in non-uniform flow distribution of flow parameters along the header length. These non-uniformities can have significant effect on the components flow rates through the individual fuel cells in the stack, resulting in a differences in operating condition between individual cells, potentially compromising overall stack performance. Present work uses numerical simulation approach to model flowfield in the inflow and outflow headers. The objective of the present work is to investigate the effects of flow disturbances in the headers on stack performance. Flow rate differences between individual cells and the extent of transient variation in the flow rates through individual cells due to disturbances in the headers are investigated. Both inflow and outflow headers are modeled as a complete system, simulating the entire feedback loop between them, allowing direct modeling of transient variations of flow rate through the individual cells.