孔隙尺度SOFC阳极传质过程

PORE-SCALE INVESTIGATION OF MASS TRANSFER IN SOLID OXIDE FUEL CELL ANODE

通过处理SOFC阳极电镜扫描图片建立包含SOFC阳极真实结构信息的几何模型,采用孔隙尺度基于两流体理论的多组分LB方法在SOFC阳极几何模型的基础上模拟SOFC阳极内部的多组分气体传质过程,计算各组分的物质的量分数分布与电极的浓差极化,研究多孔阳极微结构的各向异性所导致的传质过程的非线性变化,分析微结构形貌与浓差极化之间的定量关系。相比于常规SOFC电极传质模型需通过孔隙率与迂曲度等参数对扩散系数进行经验修正,该模型可不依赖于任何经验参数模拟真实电极内部的传递过程,从而为电极微结构优化提供科学理论根据。

A pore-scale multi-component mass transfer Lattice Boltzmann （LB） model based on two-fluid theory was developed to study multi-component reactant gas transport in SOFC anode. The geometrical model of the actual SOFC anode was derived from the scanning electron microscope image of an existing SOFC and used as an input of the LB model. The molar fraction distribution of each species and concentration polarization of the electrodes were calculated. The nonlinear variation of the mass transfer caused from the heterogeneous structure and the quantitative relationship between the microstructure and concentration polarization were discussed. Compared with the conventional mass transfer model of SOFC electrode using empirical modification of diffusion coefficient with porosity and tortuosity, the LB model established in the paper is independent on these empirical parameters since it is capable of incorporating actual geometry information of electrode directly. Therefore, it is important for the design and optimization of microstructure of SOFC electrodes.