NUMERICAL MODELING OF COUPLED HEAT/MASS TRANSPORT AND ELECTROCHEMICAL REACTIONS IN FUEL CELLS

摘要

A two-dimensional two-phase mass transport model for a liquid-feed DMFC is presented. The two-phase mass transport in the anode and cathode porous regions is formulated based on the classical multiphase flow in porous media without invoking the assumption of constant gas pressure in the unsaturated porous medium flow theory. The two-phase flow behavior in the anode flow channel is modeled by utilizing the drift-flux model, while in the cathode flow channel the homogeneous mist-flow model is used. In addition, a micro-agglomerate model is developed for the cathode catalyst layer. The model also accounts for the effects of both methanol and water crossover through the membrane. The integrated model formed by integrating the models in the different regions is solved numerically using a home-written computer code and validated against the experimental data in the literature. The model can be used to investigate the effects of various operating and structural parameters, such as methanol concentration, anode flow rate, porosities of both anode and cathode electrodes, the rate of methanol crossover, and the agglomerate size, on cell performance.