固体氧化物燃料电池（Solid Oxide Fuel Cell, SOFC）是一种高效清洁的能源转换装置，目前在商业化应用方面主要受到运行性能和寿命的限制。固体氧化物燃料电池长期运行稳定性较差，主要原因是反应气体分布不均引起温度分布不均，造成应力不均，电池出现裂纹、细缝等结构破坏。SOFC的气体分布由电池气道结构决定，受到内部多种物理化学过程的影响。SOFC尺度小，电池中多种物理量相互作用，物理场的耦合规律难以在实验中研究，且实验可测参数少、周期长、花费高。使用数值模拟的方法，可以在多尺度对电池进行研究，对电池的气道结构进行优化设计。本文利用SOFC质量、动量、能量、电荷守恒及电化学反应原理，在数值模拟软件COMSOL上建立三维模型，以实验数据为基础，用有限元分析的方法对电池进行流场、浓度场和电场的耦合模拟计算，对单气道和气道板导流结构进行设计，以使气体分布均匀，并对设计的气道板导流结构进行实验测试。在气道尺度，主要涉及气体扩散与导电性能的平衡，考虑气道宽度和高度对气体扩散的影响，气道板的埂宽及接触电阻对导电性能的影响，优化设计气道尺寸。本文基于苏州华清京昆公司提供的阳极支撑型平板燃料电池，建立并验证电池及气道板三维模型，利用多物理场耦合模型求解。根据接触情况不同，求解分析不同接触电阻、不同气道宽度及高度下的电池性能输出，得到气道板不同槽梗总宽下，气道优化尺寸以及气道宽度比例。在气道板尺度，主要涉及气体在不同气道间分布的均匀性，考虑气道前导流结构对气体流动的影响。主要评价指标包括气道间气体分布的均匀性、电流分布均匀性及总体电性能。经过计算比较现有单电池测试导流结构和电堆导流结构的压力分布、气体分布、电流密度分布及总体电性能，得出气道板进出口位置和气道前导流结构尺寸对气体分布和电流密度分布的均匀性影响，以及对电池性能的影响。针对现有单电池测试导流结构的问题，设计出新导流结构，对其进行了计算分析，多物理场模拟验证其良好的性能，并设计实验对新型导流结构进行性能测试。
Solid oxide fuel cell (SOFC) is a high-efficiency, clean, promising energy conversion device. The challenges in commercialization are the improving power density, long-term operating stability and service life. The poor stability of SOFC is mainly induced by uneven distribution of the gases, which will result in uneven temperature distribution and uneven stress distribution, leading to cracks within the cells, materials failure or other structural damage. The gas distribution of SOFC depends on flow structure and is affected by a variety of internal physical and chemical processes. Solid oxide fuel cells are small in scale, and various physical quantities in the cell interact with each other. It is difficult to study the coupling physics mechanism using experimental method. Moreover, it takes long time and high costs. Multi-physics simulation is an efficient method to study SOFC and design the interconnect structure.In this thesis, mass conservation, momentum conservation, charge conservation and electrochemistry are coupled to establish a 3D numerical model for anode-supported SOFC based on the finite element analysis software COMSOL. The multi-physical model validated with experimental data is used to explore pressure distribution, gas distribution, current distribution and performance of SOFC with different flow structures. The channel size will be optimized and a new interconnect flow structure will be designed to obtain uniform gas distribution. Experiments will be conducted to test the performance of the new designed structure.For channels optimization, it mainly involves the balance between gas diffusion and conductivity. The optimization of channel size considers the effect of channel width and height on gas transport, and the influence of contact resistance on the charge transfer. Based on an anode-supported SOFC provided by Huatsing co. Ltd, a three-dimensional multi-physical model was established and validated. The performance of cells with different width and height are compared to find out the optimal size and corresponding ratio. Considering different situation of assembly, performance of cells with different contact resistance are analyzed to illuminate the influence of contact resistance. For flow structure of interconnect plate, it influences the uniformity of gas distribution among different channels. This study explores the impact of the flow structure before channels on gas flow with main attention of overall electrical performance, uniformity of gas distribution and current distribution. After a comparison of pressure distribution, gas distribution, current distribution and cell performance between the unit cell structure for test and the flow structure in a stack, the reason for performance degradation of the unit cell structure is clear. The position of inlet and outlet pipe as well as the narrow flow zone before channels influence the gas flow, resulting in non-uniform gas distribution. The accompanying non-uniform current density distribution leads to lower overall cell performance. Based on the conclusions, a new diversion structure is designed based on the current flow structure for single-cell test. The good performance of the new structure is obtained by analysis of multi-physical modeling and the experiment.
