Abstract: Solid oxide fuel cell (SOFC) is of advantages of high efficiency, low pollution,flexibility of usable fuel types and high power, etc.Its performance and work condition is strongly affected by electro-chemical reactions coupling with various kinds of transport processes occurring in the porous anode.In this work, a 3D model is developed to describe the coupling processes based on a in-house code program.A mechanism with 42-step elementary reactions was used to evaluate the catalytic surface reaction taking place in porous anode of SOFC.The results indicate that reforming reaction providing H₂ and CO for electrochemical reaction consumes heat produced by electrochemical reaction and occur mainly in near inlet side of anode.The 70% to 80% of surface coverage in anode is covered by Ni_s, 20% to 25% by CO_s, 6% by H_s and 1.5% by O_s, and it is also found that the low utilization of Ni_s catalytic surface means in sufficient usage of fuel.The coverage of surface species depends on operating temperature, Ni_s coverage increases with increasing temperature while H_s, CO_s and O_s decrease.Reaction rate constant can affect specific coverage and operation temperature in some degree, higher rate constant of elementary reaction can make increase fuel consumption and operation temperature.So,it is possible to go up the utilization rate of fuel by improving some steps in elementary reactions.Gas transport is improved by increasing permeability that can not enhance catalytic surface reaction.

Key words: CFD analysis, SOFC model, elementary surface reaction, reaction rate constant, permeability

摘要： 固体氧化物燃料电池(SOFC)具有效率高、污染低、对燃料适应性好、功率大等特点。其性能与工作状态受发生在多孔阳极的化学反应与多种传递过程耦合的影响。基于流体力学方程组和多步基元化学反应模型,建立了描述上述耦合特性的三维数学模型,并自编程序求解分析。结果显示:重整反应主要发生在靠近通道进口的多孔阳极,表面成分Ni_s的覆盖率占70%～80%,其他主要表面成分为CO_s占20%～25%,H_s占6%,O_s占1.5%; Ni_s随工作温度升高而增加;加强吸附基元反应会提高燃料利用率和工作温度;渗透率增加会提高反应气体在多孔介质内的传递效果,但催化反应会因接触不充分而减弱。通过考虑基元反应机理研究表明,在微观层面,催化剂Ni利用率不高,催化反应受温度、化学反应速率常数、孔隙率等参数影响较大。

关键词: CFD分析, SOFC模型, 基元反应, 化学反应速率常数, 渗透率