Modeling of electrochemical reactions and species transfer processes in a direct methanol fuel cell

A two-dimensional single-phase mathematical model for a liquid-feed direct methanol fuel cell (DMFC) is presented in this paper to investigated the distribution of several key variables, including the species concentration, local current density and the local overpotential along the in-plane direction in the catalyst layer. The intrinsically coupled processes: Electrochemical reactions and species transport concerning with the electrochemical kinetics and hydrodynamics are considered. The methanol cross-over is also taken into account. A agglomerate approach is used to simulate the mass transport processes in the catalyst layers. According to the results obtained from this model, the effect of rib width on cell performance is studied and the metal foam is introduced to replace the flow field plate and diffusion layer when ribs become too thin. The simulation results indicate that the cell performance is improved and the distribution of electrochemical reaction-rate becomes more uniform with a decrease in the rib width and the best performance can be obtained when the metal foam is used.