Gas-phase particle image velocimetry (PIV) for application to the design of fuel cell reactant flow channels

Because the parasitic load on most polymer electrolyte fuel cell systems is dominated by pressure losses across the flow fields, understanding the flow channel dynamics has garnered significant recent attention. The current work is aimed at enabling advanced design of reactant flow channels by elucidating the details of the velocity fields within various reactant flow channel geometries. Gas-phase measurement is critical to ensuring that the results are valid for real fuel cell systems, and for application of this technique to the study of flow channels with two-phase obstruction phenomena. In the current research, gas-phase velocity fields have been measured using particle image velocimetry (PIV) in representative geometries, including a straight channel (for technique validation) and a 180° switchback with channel-to-land ratio of 1:1. The accuracy of the measurement depends on the ability of the seed particles to follow the flow. Numerical simulations have been performed to develop a criterion for identifying appropriate seed particles. The research presented is a first step toward measuring velocity fields in novel flow reactant channels in operational cells.