Three-dimensional multi-phase simulation of PEMFC at high current density utilizing Eulerian-Eulerian model and two-fluid model

摘要

A 3D (three-dimensional) multi-phase model of PEMFC (proton exchange membrane fuel cell) is developed, in which the Eulerian-Eulerian model is utilized to solve the gas and liquid two-phase flow in channels, while the two-fluid model is adopted in porous electrodes. Hence, the surface tension, wall adhesion and drag force in channels are all included. Besides, the gravity effects in the whole PEMFC are also taken into consideration. It is found that the water vapor concentration in cathode channel at high inlet humidity (e.g. 1.0) will be much higher than the saturation concentration if neglecting the water vapor condensation. In addition, the liquid water condensed from vapor in channel is mainly blown to side walls, rather than only exist on the bottom surface. The effect of water condensation and evaporation in channel is found to be lower than that in porous electrodes because of the much higher gas velocity in channel. Besides, the partial low temperature is likely to cause local liquid water accumulation in both anode and cathode channels and porous electrodes. Meanwhile, the wave-like channel is found to be able to remove the liquid water effectively due to the enhanced convection effect. Meanwhile, the simulation results in this study show that the serpentine flow field is much more beneficial to the liquid water removal and reactant gas distribution than parallel flow field, which results in the much higher performance.