流场结构对PEM电解槽性能影响模拟

Simulation of the effect of flow channel structure on the performance of PEM electrolyzer

为了提高质子交换膜(PEM)电解槽的性能,降低电压损耗,提升运行稳定性,在一定假设条件下,使用Comsol软件建立了全尺寸多通道的质子交换膜电解槽三维模型,并将仿真计算结果与文献中同尺寸PEM电解槽试验测试结果进行对比验证,仿真结果与文献试验测试结果基本吻合。基于此电解槽模型研究了流道高度、堵块、脊宽度等对PEM电解槽性能的影响,从而优化流场结构。仿真结果显示,在研究设定的PEM电解槽尺寸下,最佳流道高度为2 mm;在流道顶部设置堵块可使扩散层内氧气质量分数下降约2.6%,膜电极平均温度下降2.2 K左右,电解槽的电解电势减少0.0235 V左右;流场脊宽度由2 mm减小至1 mm时,平均氧气质量分数下降约8.7%,膜电极平均温度下降6.21 K,电解槽电解电势下降0.04 V左右。优化后的流场结构有利于循环水带走扩散层内氧气,降低氧气气泡堵塞扩散层孔隙的可能性,减小传质阻力,增强传热过程,及时排出电解槽中多余热量,降低电解槽电解电势,提高电解槽性能和运行稳定性。

In order to improve the performance of proton exchange membrane(PEM)electrolyzer,reduce the voltage loss,and enhance the operational stability,a three-dimensional model of a full-size multi-channel PEM electrolyzer was established using Comsol software under certain assumptions.the simulation calculation results were compared with the experimental test results of the same size PEM electrolyzer in the literature to verify that the simulation results were basically consistent with the experimental test results in the literature.The effects of runner height,blocking and ridge width on the performance of PEM electrolyzer were investigated to optimize the flow field structure based on this electrolyzer model.The simulation results show that the optimal flow channel height is 2 mm under the PEM electrolyzer size set in the study.The oxygen mass fraction in the diffusion layer can be reduced by about 2.6%,the average temperature of the membrane electrode can be reduced by about 2.2 K,and the electrolytic potential of the electrolyzer can be reduced by about 0.0235 V by setting the block at the top of the flow channel.When the width of the ridge of the flow field is reduced from 2 mm to 1 mm,the average oxygen mass fraction is decreased by about 8.7%,the average temperature of the membrane electrode is decreased by 6.21 K,and the electrolytic potential of the electrolyzer is decreased by about 0.04 V.The optimized flow field structure is conducive to take away oxygen in the diffusion layer for circulating water,and reduce the possibility of oxygen bubbles blocking the pores of the diffusion layer,reduce the mass transfer resistance,and enhance the heat transfer process to discharge the excess heat from the electrolyzer in time,reduce the electrolytic potential of the electrolyzer,and improve electrolyzer performance and operational stability.