Experimental validation of a methanol crossover model in DMFC applications
Experimental validation of a methanol crossover model in DMFC applications
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DOI：
10.1016/j.jpowsour.2007.11.102
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发表时间：
2008-05
影响因子：
9.2
通讯作者：
S. Eccarius;B. García;C. Hebling;J. Weidner
中科院分区：
文献类型：
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作者：
S. Eccarius;B. García;C. Hebling;J. Weidner
采用实验设计和数学模型研究了直接甲醇燃料电池（DMFC）中甲醇渗透的影响因素。实验的设计检查温度，阴极化学计量，阳极甲醇流速，夹紧力，阳极催化剂负载，阴极催化剂负载（CCL），和膜厚度作为电流的函数的影响，它也考虑了任何两个这些因素之间的相互作用。分析表明，温度、阳极催化剂层厚度和甲醇浓度是影响甲醇穿透的显著因素。分析还表明，这些变量如何影响总甲醇穿越不同的方式，由于甲醇通过膜的扩散，电渗阻力，和甲醇在阳极和阴极的反应速率的影响。例如，正如预期的分析表明，扩散受到阳极和阴极界面浓度、阳极催化剂层和膜的厚度以及膜中的扩散系数的显著影响。不太明显的是，在低阴极流速下甲醇渗透的减少是由于在膜/阴极催化剂层界面处形成甲醇膜。细胞膜中的扩散阻力和电渗阻力的相对比例随细胞电流的变化而显著变化。
A design of experiments (DOEs) coupled with a mathematical model was used to quantify the factors affecting methanol crossover in a direct methanol fuel cell (DMFC). The design of experiments examined the effects of temperature, cathode stoichiometry, anode methanol flow rate, clamping force, anode catalyst loading, cathode catalyst loading (CCL), and membrane thickness as a function of current and it also considered the interaction between any two of these factors. The analysis showed that significant factors affecting methanol crossover were temperature, anode catalyst layer thickness, and methanol concentration. The analysis also showed how these variables influence the total methanol crossover in different ways due to the effects on diffusion of methanol through the membrane, electroosmotic drag, and reaction rate of methanol at the anode and cathode. For example, as expected analysis showed that diffusion was significantly affected by the anode and cathode interfacial concentration, by the thickness of the anode catalyst layer and membrane, and by the diffusion coefficient in the membrane. Less obvious was the decrease in methanol crossover at low cathode flow rates were due to the formation of a methanol film at the membrane/cathode catalyst layer interface. The relative proportions of diffusion and electroosmotic drag in the membrane changed significantly with the cell current of the cell.