流线型挡板对PEMFC性能的影响

Effect of Streamlined Baffles on PEMFC Performance

优化质子交换膜燃料电池PEMFC(proton exchange membrane fuel cell)的流道结构是强化反应气体传输及提升输出性能的一种重要方法。在PEMFC直流道中添加了一种新型流线型挡板结构,与矩形挡板进行了对比,并分析了流线型挡板的背风面长度对PEMFC传质特性的影响。最后在平行流场中添加流线型挡板,研究了挡板的分布方式对PEMFC性能的影响。结果表明,在直流道内添加挡板提高了挡板下方反应气体的流动速度,增加了扩散层中的反应气体总通量,PEMFC电流密度得到提高。当流线型挡板的背风面长度增加时,有利于减小挡板后方的涡流大小。此外,在平行流场中添加流线型挡板并采用交错分布时,增大了平行流场中的反应气体压降,提高了催化层中的反应气体浓度。当工作电压为0.5 V时,采用交错分布平行流场的PEMFC电流密度比常规平行流场提高了3.4%。研究结果可为今后挡板优化及分布方式的研究提供理论基础和技术储备。

The optimization of the flow channel structure of a proton exchange membrane fuel cell(PEMFC) is an important method to enhance the reaction gas transport and improve the output performance. In this paper, a novel streamlined baffle structure is added to the straight flow channel of PEMFC, which is further compared with a rectangular baffle. Then, the effect of the streamlined baffle’s leeward side length on the mass transfer characteristics of PEMFC is also analyzed. Finally, streamlined baffles are added to the parallel flow fields, and the effect of distribution methods for baffles on the PEMFC performance is investigated. Results show that adding baffles to the straight flow channel increases the reaction gas’ s flow velocity below the baffles, increases the total flux of reaction gas in the gas diffusion layer, and improves the PEMFC’s current density. The increase in the streamlined baffle’s leeward side length is beneficial to reducing the size of the vortex behind the baffle. In addition, when streamlined baffles are added to the parallel flow fields and the baffles are further staggered, the pressure drop of reaction gas in the parallel flow fields is raised and the concentration of reaction gas in the catalytic layer is increased. The current density of PEMFC with staggered parallel flow fields increases by 3.4% compared with that with the conventional parallel flow fields when the operating voltage is 0.5 V.The results in this paper provide a theoretical basis and technical reserve for the future research on baffle optimization and distribution methods.