Abstract: With emphasis on the influence on the performance of air-breathing PEMFC (proton exchange membrane fuel cells) by various channel widths and rib widths, a coupled model was developed.In this model,natural convection in the channel and porous media was included, and concentration over potential was considered as a result of limited supply of oxygen in the catalyst layer.From the calculation, water and species distribution, temperature profile and polarization curves were simulated for the variation of cathode rib width and channel width. Results from the model indicated that concentration loss was more serious in natural convection than in forced convection, especially at a small channel opening size.The performance of air-breathing PEMFC could be improved by increasing channel opening size to some extent.Solid temperature, channel size and air flow rate interacted with each other, and the performance could not be improved infinitely by increasing channel size， and thus cathode flow field should be optimized.This work is useful for optimizing channel configuration.

摘要： 空气自然对流的小型燃料电池不同于强制对流下工作的燃料电池，阴极反应气来源于空气的自然对流.由于这一自然对流的特性，电池内部的质量、能量、动量以及电化学反应方程存在着极强的耦合关系.从水、热管理的角度，考虑了电池内部的流动、电化学反应、热和质量的传输，以及它们之间的相互关系，建立了空气自然对流下的质子交换膜燃料电池的二维数学模型. 针对不同的阴极流道宽度和间隔宽度，对温度、流动速率、分压以及电化学性能参数等进行了计算，分析了这些参数之间的相互影响.有助于理解电池内部现象之间的相互关系，对燃料电池双极板和电池结构设计有指导意义.