Simulation of the current density distribution for a PEMFC by using measured electrochemical and physical properties of the membrane

摘要

In order to grasp properly PEFC power generation performances, it is necessary to know aspects of water management such as transmissivity and electro-osmotic coefficient of water vapor through the membrane, and factors for power loss such as active and resistive overpotentials. In this study we have measured these factors to analyze our experimental results of PEFC power generation tests by our two-dimensional simulation code. It considers simultaneously the mass, charge and energy conservation equations, and the equivalent electric-circuit for PEFC to give numerical distributions of hydrogen/oxygen concentrations, current density, and gas/cell-component temperatures. The numerical distributions of current density under various operating conditions agreed well with the measured distributions by segmented electrodes, which had grooves for hydrogen/oxygen supply and were molded in our test cell being electrically insulated. Hydrogen/oxygen concentration changes measured by gas chromatography along the gas supply grooves gave also the experimental current distributions, which coincided almost with those by the segmented electrodes. Factors to correct the small difference between the measured and the calculated are also discussed from the stand point of the physical meaning of the calculated results considering factors which are not taken into account in our code.