Study On Water And Gas Transport Of PEMFC

Water and gas transport in channels of Proton exchange membrane fuel cell (PEMFC) have a great influence on its performance and life. Visualization technique is one of the most useful tools to study the water and gas transport characteristics. The formation and movement of gas bubbles or water droplets in channels are truly presented by the visualization study. Moreover, it can help us to understand the evolution mechanism, optimize the water and gas management and improve the performance of the fuel cell. This work focused on studying on water and gas transport characteristics by visualization and use high-speed cameras record the water and gas transport in the channels. The main research contents and results are as follows:(1) Visual observation for the cathode of PEMFC, discover Two-phase flow distribution inside the channels and Liquid water distribution and formation. Two-phase always in a slug flow and annular flow area.(2) Visual observation of the fuel cell at the different operating parameters on the impact of two-phase flow. Quantitative analyze of liquid water at various operating parameters and determine the cell too wet or too dry. At last, select the optimal operation parameters of PEMFC.(3) Visual observation for the anode of PEMFC, there is no water droplets formation in channels at the High current density.But there have a little of water droplets formation and collect at the low current density.(4) When the fuel cell at the high current density and The anode side of the gas export plug to prevent gas emissions, this will result in the formation of two-phase flow rapidly and the fuel cell performance is improved. After a few minutes, the performance of fuel cell will decline because of the impurities can not be taken away. According to this behavior, we can constitute the control policy with the anode export at the working time. To control the opening and closing time of Hydrogen export so that the fuel cell performance will remain at a high level. (5) At the fuel cell working time, The Drain and Gas diffusion was very hard in the absence of hydrophobic carbon paper. Drilling is propitious to The reaction mass transfer, accumulation and discharge of liquid water. The fuel cell performance will be improved.(6) The channel of trapezoidal cross-section is not conducive to the flowing of liquid water, but the channel of Inverted trapezoidal cross-section is propitious to the flowing of liquid water and fuel cell is not easily lead "flooding". Under the same conditions, the liquid discharge easy to difficulty in the order is:Inverted trapezoidal cross-section, Rectangular, trapezoidal cross-section.