Institute of Fuel Cell, School of Mechanical Engineering, Shanghai Jiao Tong University, Dongchuan Rd. 800, Shanghai, China.
Sci Rep. 2017 Mar 2;7:43447. doi: 10.1038/srep43447.
The flow field configuration plays an important role on the performance of proton exchange membrane fuel cells (PEMFCs). For instance, channel/rib width and total channel cross-sectional area determine the under-rib convection and pressure drop respectively, both of which directly influence the water removal, in turn affecting the oxygen supply and cathodic oxygen reduction reaction. In this study, effects of under-rib convection and pressure drop on cell performance are investigated experimentally and numerically by adjusting the channel/rib width and channel cross-sectional area of flow fields. The results show that the performance differences with various flow field configurations mainly derive from the oxygen transport resistance which is determined by the water accumulation degree, and the cell performance would benefit from the narrower channels and smaller cross sections. It reveals that at low current densities when water starts to accumulate in GDL at under-rib regions, the under-rib convection plays a more important role in water removal than pressure drop does; in contrast, at high current densities when water starts to accumulate in channels, the pressure drop dominates the water removal to facilitate the oxygen transport to the catalyst layer.
流场构型对质子交换膜燃料电池（PEMFC）的性能起着重要作用。例如，通道/肋的宽度和总通道横截面积分别决定了肋下对流和压降，这两者直接影响水的去除，进而影响氧气供应和阴极氧还原反应。在这项研究中，通过调整流场的通道/肋宽度和通道横截面积，实验和数值研究了肋下对流和压降对电池性能的影响。结果表明，各种流场构型的性能差异主要来自于氧气传输阻力，该阻力由水积累程度决定，较窄的通道和较小的横截面有助于提高电池性能。结果表明，在低电流密度下，当水开始在肋下区域的 GDL 中积累时，肋下对流在水去除方面比压降更重要；相反，在高电流密度下，当水开始在通道中积累时，压降主导水去除以促进氧气向催化剂层的传输。
