千瓦级交错流 SOFC 电池堆多物理场分布特性与性能

Multiphysics distribution characteristics and performance study of kWclass crossflow SOFC stack

  • 摘要: 固体氧化物燃料电池通常运行在 700 °C 以上的高温环境中,大型电池堆的实验研究成本 高,且难以对电池堆内部运行状态进行测量,数值模拟成为探究其内部气-热-电分布特性的重要 研究手段。 由于固体氧化物燃料电池内部存在化学反应、电化学反应和传热、传质等多种物理场的 相互耦合,针对常规多物理场全耦合模型难以对大型电池堆进行仿真计算的问题,提出了一种基于 BP 神经网络的多物理场解耦模型,并对千瓦级交错流固体氧化物电池堆的流场、温度场分布特性 和 I-V 性能进行了模拟计算。 研究结果表明:通过增大燃料进气流量和运行温度可提高电池堆输 出功率,但前者影响电池堆燃料利用率和发电效率,后者导致电池堆内部的热应力增大,有密封失 效和结构损坏的风险。 合理选择燃料气流道高度和配气腔容积能够对燃料流量均匀性具有显著影 响。 计算结果显示,当燃料气流道高度从 0.5 mm 降至 0.3 mm 时,电池堆在燃料流量均匀性提升 2%的情况下最大温度差降低了 17%,表明较好的燃料流量均匀性能较大程度的改善电池堆内部温 度场分布,降低电池堆最大温度和热应力。 通过与自研的千瓦级电池堆实验结果对比,表明该多物 理场解耦研究方法能够很好的应用于大型电池堆的模拟计算。

     

    Abstract: Solid Oxide Fuel Cell (SOFC) usually operates in a high temperature environment above 700 ℃. The experimental research of a largescale stack is expensive, and it is difficult to evaluate the internal state of the stack. Modeling the SOFC stack has become an important research method to explore its internal gas thermalelectricity distribution characteristics. Due to the mutual coupling of various physical fields such as chemical reaction, electrochemical reaction, heat transfer, and mass transfer in the fuel cell, it is difficult to simulate and calculate the largescale stacks with conventional multi physics fully coupled models. Therefore, a multi physics decoupling model based on the BP neural network is proposed, and the flow field, temperature field distribution characteristics and I-V performance of the kilowatt class crossflow stack are simulated and calculated. The research results show that increasing the intake flow rate and operating temperature can directly enhance the output power of the stack. However, these operations reduce stack fuel utilization and power generation efficiency, and lead to increased thermal stress inside the stack, with the risk of leakage and structural damage. The height of the anode PEN and the volume of the gas distribution cavity should be carefully chosen since they can significantly affect the gas flow uniformity of the stack. The results show that the gas flow uniformity of the stack is improved by 2% when the height of PEN is changed from 0.5 mm to 0.3 mm, and the maximum temperature difference is reduced by 17%. Therefore, a stack with better gas flow uniformity can significantly improve its temperature field distribution and reduce its maximum temperature and internal thermal stress. The verification with the experimental results of the kilowattclass crossflow stack shows that the multiphysics decoupling model can be well applied to the simulation of largescale SOFC stacks and lay a foundation for the further optimization of largescale stacks.

     

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