甲烷固体氧化物燃料电池多物理场模拟及积碳分析

建立了相关实验电池多物理场模型，该模型包括了电化学反应的电化学势平衡方程、甲烷水汽重整的通用速率方程和描述阳极复杂组分气体输运的菲克定律形式尘气模型. 该理论模型的电流～电压 曲线与实验数据很好地吻合，验证了理论模型的有效性. 理论分析发现，低水汽含量甲烷重整反应中水汽的反应级数为1. 理论模型的数值仿真计算还给出多个物理量的详细信息. 据此对碳沉积机制进行深入分析，清楚地描述了工作电流对抑制焦炭生成的机制. 分析比较了积碳活性的两个表达式，发现它们都可以正确地定性反映积碳活性变化趋势，但定量数值并不确切；阳极扩散层降低积碳临界电流的机制也获得了解释. 值得指出的是，虽然积碳活性模型只是定性正确，但分析表明积碳临界电流的降低却可以通过积碳活性模型进行定量解释.

Multi-Physics Modeling of Solid Oxide Fuel Cell Fueled by Methane and Analysis of Carbon Deposition

Internal reformation of low steam methane fuel is important for the high e ciency and low cost operation of solid oxide fuel cell. Understanding and overcoming carbon deposition is crucial for the technology development. Here a multi-physics model is established for the relevant experimental cells. Balance of electrochemical potentials for the electrochemical reactions, generic rate expression for the methane steam reforming, dusty gas model in a form of Fick's model for anode gas transport are used in the model. Excellent agreement between the theoretical and experimental current-voltage relations is obtained, demonstrating the validity of the proposed theoretical model. The steam reaction order in low steam methane reforming reaction is found to be 1. Detailed information about the distributions of physical quantities is obtained by the numerical simulation. Carbon deposition is analyzed in detail and the mechanism for the coking inhibition by operating current is illustrated clearly. Two expressions of carbon activity are analyzed and found to be correct qualitatively, but not quantitatively. The role of anode diffusion layer on reducing the current threshold for carbon removal is also explained. It is noted that the current threshold reduction may be explained quantitatively with the carbon activity models that are only qualitatively correct.