Concentration gradient of reactants extending from reaction sites inward inlet periphery of fuel cells
Concentration gradient of reactants extending from reaction sites inward inlet periphery of fuel cells
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DOI：
10.1149/2.0871805jes
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发表时间：
2018
影响因子：
3.9
通讯作者：
Özgür Aydın;H. Nakajima
中科院分区：
文献类型：
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作者：
Özgür Aydın;H. Nakajima
反应物和生成物进出反应地点的运输对燃料电池的电化学能量转换性能有很大影响。在高反应物利用率下，质量输运可能成为性能限制因素，导致活性场中电流和温度等发生显著变化。为了克服质量输运的限制，可以以高速率提供反应物和设计适当的流场，这两者的数值模拟都是很有价值的。在这些方面，虽然最关心的是细胞/堆活性区域内的物质运输，但在这里，我们显示了入口边缘的质量运输限制的开始，即在高反应物利用率下，反应物的浓度梯度从反应点向入口边缘延伸。我们利用微管固体氧化物燃料电池（SOFC）在模拟其电化学性能时出现的浓度分布计算误差来澄清这一现象。为了消除燃料电池数值研究中的这种误差，我们提出并论证了一种实用的方法。我们还确定了消耗/供应质量通量的临界比率，以评估相关（反应物种）SOFC系统在其入口外围的质量传输限制。
Transport of reactants and products to/from reactions sites affects the electrochemical energy conversion performance of fuel cells substantially. At high reactant utilization rates, mass transport can be the performance limiting factor, resulting in significant variations of current and temperature, etc. in the active field. To overcome mass transport limitations, reactants can be supplied at high rates and proper flow fields can be designed, for both of which numerical simulations are quite valuable. In these regards, although the highest care is put on the transport of species within active area of cells/stacks, herein we show the onset of mass transport limitation in the inlet periphery, ie, extension of the concentration gradient of reactants from reactions sites inward the inlet periphery at high reactant utilization rates. We clarify this phenomenon leaning upon the computational error appearing in the concentration profile of a microtubular Solid Oxide Fuel Cell (SOFC) while simulating its electrochemical performance. For eliminating this error in numerical studies of fuel cells, we propose and demonstrate a practical method. We also determine the critical ratio of consumed/supplied mass fluxes for evaluating relevant (reactant species) SOFC systems in terms of the mass transport limitation in their inlet peripheries.