质子交换膜水电解中气-液两相传输的模拟研究

两相传输是影响质子交换膜水电解系统性能的关键因素。为掌握质子交换膜水电解单元中多孔扩散层内气液两相传输规律,基于数值重构的三维多孔扩散层结构,采用格子Boltzmann两相流动模型模拟研究了扩散层内两相传输过程,详细分析了扩散层孔隙率和表面接触角对气泡传输与分布的影响。数值模拟结果表明：孔隙率减小会明显降低气体渗透率,从而导致气泡难以在扩散层内找到有效传输通道。接触角的增大不仅增加了气泡在界面堆积的风险,也减缓了气泡在孔隙内的传输速度。从孔隙尺度水平初步掌握了质子交换膜水电解单元多孔扩散层内两相传输规律,可为高性能水电解系统设计和优化提供理论支撑。

Simulation of Gas/Liquid Two-Phase Transport in Proton Exchange Membrane Water Electrolysis

Two-phase transport is the key factor that affects the performance of the proton exchange membrane (PEM) water electrolysis system. The lattice Boltzmann method (LBM) was employed to simulate the two-phase transport process in a three-dimensional reconstructed porous diffusion layer for the mechanism of gas/liquid two-phase transport inside the porous diffusion layer of a PEM water electrolysis cell. The relevant simulations were conducted to study the effects of the porosity and surface contact angle of the diffusion layer on the gas bubble transport and distribution. Numerical results indicated that the gas permeability of the diffusion layer significantly reduced as the porosity decreased, which made it difficult for gas bubbles to get the effective transport pathway inside the diffusion layer. Additionally, as the contact angle increased, the risk of gas bubble accumulation on the interface increased, and the velocity of gas bubble transport in the pores also slowed down. A fundamental understanding of the pore-scale two-phase transport mechanism in the porous diffusion layer of the PEM water electrolysis cell was obtained, which might provide theoretical support for the design and optimization of a high-performance water electrolysis system.