Numerical investigation of methanol crossover through the membrane in a direct methanol fuel cell

Abstract

A two-dimensional, single-phase, isothermal model has been developed for a direct methanol fuel cell (DMFC). The model considers the anode and cathode electrochemical equations, continuity, momentum and species transport in the entire fuel cell. Then, the equations are coupled together and solved simultaneously using a commercial, finite element based, COMSOL Multiphysics software. The crossover of methanol is also investigated in the model. This model describes the electrochemical kinetics of methanol oxidation at the anode catalyst layer by non-Tafel kinetics. The concentration distribution of methanol, water, and oxygen was predicted by the model. In addition, the changes of methanol crossover and fuel utilization with current density were evaluated for different methanol concentrations (0.5 M, 1 M, 2 M, 4 M, and 6 M). Furthermore, it was also found that the crossover of methanol decreases at low methanol concentrations and high current densities. The results show that the polarization curve is in agreement with experimental data.