质子交换膜燃料电池流场及气场系统优化设计

Optimum design of gas and flow field system of PEMFC

将各气场部件作为一个完整的系统考虑,分层次进行气场均匀性设计.首先对外置型空气进气箱结构进行优化设计,使得各单电池的进口流量均匀性得到较大提高;然后对气场的流道型式(直型、蛇型、交指型、单进口、多进口)、尺寸和流动方式(顺流、逆流)以及扩散层的厚度、孔径、孔隙率和分布形态对气场均匀性的影响以统一模型描述,利用CFD软件对流道形式、流道截面尺寸和扩散层孔隙度与孔径等参数进行优化设计,认为计算的3种几何模型中直流道催化层表面氧气浓度分布相对比较均匀;流道宽度减少流道条数增多、扩散层孔隙率和孔径适当减小等都可使得催化层表面氧浓度分布均匀性提高.研究结果对燃料电池气体扩散场的设计具有一定参考意义.

Taking the gas field parts as a system, the uniformity of the gas field is designed hierarchaly. Firstly the structure of the extra-manifold air box is optimally designed so as to get a relatively uniform air input for each cell; then the influence on uniformity of gas channel types（straight, serpentine, interdigitated, single inlet and mult-inlet）, size and flow manner（co flow and anti flow）, thickness, pore di ameter, porosity and distribution of GDL （gas diffusion layer） is expressed in a set of equations; the variables are optimally designed through CFD software. Some conclusions are made as follows： the oxygen concentration reaching to the surface of the catalyst layer of the straight channel is the most uni form; decreasing the width, increasing the channel number and decreasing aptly the porosity and pore diameter of the GDL can improve the uniformity. The conclusions are helpful for the design of PEMFC.