具有堵块结构的PEMFC阴极流场的传质性能

Mass transfer performance of PEMFC cathode flow field with blockage structure

建立具有堵块结构的质子交换膜燃料电池(PEMFC)阴极流场模型,分析堵块的布置方式(上方、下方、上下交错)和孔隙率对流道和扩散层内气体流动特征(速度、压力和氧气摩尔浓度等)的影响,以及对流道中间和出口处堵块的前中部位垂直于流道方向的传质影响。通过可视化实验分析液态水在具有不同堵块高度流场中的运动特性。当矩形堵块布置在流道上方时,在中间和出口处堵块的前中后部位都能获得更好的垂直于流道方向的传质性能;流道上方布置矩形堵块能加速液态水的排出。当堵块高度为50%流道高时,流场大多数液滴的灰度值为40~70,已经对流道造成堵塞;当堵块高度为70%流道高时,多数液滴的灰度值为70~90,且较多液滴分布在流道出口处,液态水排出较为通畅。

A proton exchange membrane fuel cell(PEMFC)cathode flow field model with the blockage structure is established.The effects of blockage arrangement(above,below,in an alternating pattern)and porosity on the gas flow characteristics(velocity,pressure and oxygen molar concentration)in the flow channel and diffusion layer,as well as the mass transfer in the vertical direction to the channel of the front,middle,and rear blockage sections in the middle and outlet of channel are analyzed.The movement characteristics of liquid water in flow fields with different blockage heights are analyzed by visual experiment.When rectangular blockages are placed above the channel,better mass transfer performance in the vertical direction to the channel is achieved in the middle and outlet of the front,middle and rear blockage sections;positioning rectangular blockages above the channel accelerates the discharge of liquid water.When the blockage height is 50%of the channel height,the grayscale values of most droplets in the flow field are 40-70,causing blockages in the channel.When the blockage height is 70%of the channel height,the grayscale values of most droplets are 70-90,and a significant number of droplets are distributed at the outlet of the channel,resulting in smoother discharge of liquid water.