Modeling PEMFC With FLUENT: Numerical Performance and Validations With Experimental Data

A 3-dimensional, two-phase Computational Fluid Dynamics (CFD) model for PEMFC simulations has been developed and implemented in FLUENT, a general-purpose commercial software package with multi-physics capabilities. The model formulation was given in details in the previous ASME fuel cell conference, together with in-situ distributions of current densities and species concentrations computed for a simple geometry. In this paper, numerical performance of this model in terms of computing time and parallel efficiency are assessed through the computation of a relatively larger-size fuel cell (50 cm²) with serpentine channels. The convergence history and parallel performance data show that the Fluent’s PEMFC model is numerically robust and efficient. In addition to the numerical performance, the physical validity of the model is tested through comparisons with experimental data of polarization curves and local current density distributions from the most recent work of Mench et al [1]. Comparisons with the data show good agreement in the overall polarization curves and reasonably good agreement in local current density distributions too. The comma-shaped local polarization curves seen in the experiments are qualitatively correctly captured. Moreover, our computations show that hydrogen mass fraction and molar concentration can both increase along the anode flow channel, despite that hydrogen is being depleted in the anodic electrochemical reaction. The reason for this to happen is that the osmotic drag moves the water from anode to cathode at a much faster rate than the hydrogen depletion rate. An analytical derivation that reveals the relationship between species molar concentration and mass fraction is also given.