Three-dimensional effects of liquid water flooding in the cathode of a PEM fuel cell

Abstract

A two-dimensional model available in the literature for conventional gas distributors was expanded to account for the dimension along the length of the channel. The channel was discretized into control volumes in series that were treated as well mixed. An iterative solution procedure was incorporated in each control volume to determine the average current density and the corresponding oxygen consumption and water generation rates. Down stream channel concentrations were calculated based on stoichiometric flow rates and the solution obtained from the preceding control volumes. Comparison of the model results with experimental data and the existing two-dimensional model showed that accounting for the oxygen concentration variations along the channel and its effect on the current density is critical for accurately predicting the cathode performance. Variations in the current density along the channel were strongly influenced by the changes in oxygen concentration caused by consumption due to reaction and dilution caused by water evaporation. Operating parameters that facilitated better water removal by evaporation like higher temperature and stoichiometric flow rates and lower inlet stream humidity resulted in higher net current. Operating conditions that resulted in minimal loss in oxygen concentrations resulted in a more uniform current density distribution along the channel.

Modeling Water Management in Polymer-Electrolyte Fuel Cells

“…Furthermore, it is often seen that the rearrangement of liquid water and development of the saturation profiles are the longest time constants in the system. 181,285,304 While this is known, transient modeling with two-phase flow becomes very complicated, and there are only a few such models currently.…”

Thermal Conductivity and Contact Resistance of Compressed Gas Diffusion Layer of PEM Fuel Cell

“…Because of its low operating temperature, typically less than 100 ˚C, the product water often remains in liquid form within the cell. The condensed water may flood the cell which significantly hinders mass transport [1][2][3][4][5][6][7]. Therefore, flooding must be properly prevented by e.g.…”

Macroscopic Modeling of Polymer-Electrolyte Membranes

“…These models are aimed at examining effects outside the membrane (e.g., cathode flooding [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]) or when only general trends are desired [49][50][51][52][53][54].…”