| As one of the most promising hydrogen-based energy conversion devices, the polymer electrolyte fuel cell (PEFC) has been through intense development in the last two decades. Ultra-high current operation, which cannot be normally achieved at a reasonable voltage by the commonly used cell architecture, has been enabled by material advancement and cell design lately. However, a robust model is needed to rise to the unprecedented challenges in heat and water management. A comprehensive 2D + 1 computational model has been developed in this work to explore the operation of a PEFC with open metallic element (OME) porous flow field in the ultra-high current regime.;In most of previous modeling works, the model validation has been generally limited to polarization curve comparison under single selected condition. This model distinguishes itself from the others in that it has been validated to a greater extent, including in-situ experimental measurement of performance, area specific resistance (ASR), and net water drag (NWD) coefficient. Data furnished by experimental diagnostics under a wide range of operating parameters serve as benchmark for model validation. Results also highlight the utility of experimentally-determined anode dry-out limits for validating multi-phase models.;The collaborative experimental and modeling investigation shows that gas phase oxygen transport, which is responsible for limiting current density observed with conventional parallel flow field, is not the limiting factor in OME porous flow field, even in the ultra-high current regime. Notwithstanding the significant performance improvement of OME porous flow field at high current, anode dry-out limits the performance, as confirmed by NWD data from both experiment and model. Moreover, diffusive transport has been determined to be the dominant mode of water removal from the catalyst layer in an OME porous flow field, compared to capillary action and convective flux.;Thermo-osmosis, which is a regularly-observed mode of water transport across membrane in experiments but relatively minor due to low performance and low temperature gradient achieved in conventional parallel flow field, demonstrates its non-negligible effect in comparison to electro-osmosis, especially under hot and dry high power density conditions, even with thin polymer electrolyte membranes.;The extensively-validated model is then applied to engineer cell operation so that anode dry-out can be mitigated in high temperature high power density operating regime, desired for automotive application. Predictions of internal water distribution demonstrate that moderate changes in operating parameters, such as pressure, stoichiometry and humidity, help maintain a hydrated anode stream and therefore enable a 20 °C increase in stable operating temperature than the baseline case, making heat dissipation to the cooling system more efficient. |
