Multiphase Mixture Modelling and Experimentation of the Flowing Electrolyte – Direct Methanol Fuel Cell

A one dimensional, steady state, isothermal multiphase mixture model has been developed for the FE-DMFC and has been compared to experimental FE-DMFC results. The effects of porosity and permeability concerning the flowing electrolyte channel (FEC), and membrane thickness for both the anode and cathode have been modeled to determine their effect on methanol crossover. From this study, it has been found that a FEC porosity less than 0.25, yielded negligible variation in crossover current density with current density. It was also determined that permeabilities greater than 10⁻⁹ began to show lower decreases in the crossover current density. This is due to a smaller contribution from capillary-induced velocity. Furthermore, it was found that a thin anode membrane and thick cathode membrane should be used for manageable levels of methanol crossover and minimal Ohmic losses. Although this will yield greater methanol crossover, when compared to a thicker membrane being used for both the anode and cathode, the flowing electrolyte flow rate can be increased to return the methanol crossover flux to manageable levels.