PEM电解池氧气分布及压缩条件下性能研究

Investigation of Oxygen Distribution and Performance Under Compression of PEM Electrolysis Cell

质子交换膜电解池(PEMEC)被广泛认为是耦合可再生能源制取绿氢的理想装置。然而电解池内局部氧气分布特征和装配压力对电解池性能规律尚不明确,给电解池结构优化和性能提升带来巨大挑战。本文首先结合ANSYS Fluent编写用户自定义代码实现了电解池的三维多相多物理场仿真,探究了孔隙率和接触角对多孔电极内氧气分布的影响。然后采用VOF(Volume of Fluid)方法和图像识别,与全电池模型耦合迭代的方法明确了氧气在流道中的聚集特征。最后提出了接触电阻模型,对不同压缩工况下电解池的性能进行分析。结果表明,增大孔隙率和降低接触角可加强脊下传质,氧气倾向于在流道近脊处生成,进而向中间聚集,最终形成段塞流;当电流密度为0.8 A/cm^(2)时,忽略接触电阻将会低估0.17 V的电压。

Proton exchange membrane electrolysis cells(PEMEC) are widely considered ideal devices for coupling renewable energy sources to produce green hydrogen. However, the local oxygen distribution characteristics within the electrolysis cell and the effect of assembly pressure on cell performance are not yet well understood, posing significant challenges for optimizing the cell structure and enhancing its performance. In this study, the ANSYS Fluent with the user-defined function code is first employed to simulate the three-dimensional multiphase and multi-physical fields of the electrolysis cell. The influence of porosity and contact angle on the oxygen distribution within the porous electrode is investigated. Then the accumulation characteristics of oxygen in the flow channel are determined by the volume of fluid(VOF) method and image recognition, and coupling iteration with the full cell model. Furthermore, a contact resistance model is proposed to analyze the performance of the electrolysis cell under different compression conditions. Results indicate that increasing porosity and reducing contact angle can enhance the mass transfer under the land, and oxygen bubbles tend to generate near the land, subsequently accumulating and growing towards the center of the channel, forming plug flow. When the current density is 0.8 A/cm^(2), neglecting the contact resistance would underestimate the voltage by 0.17 V.