摘 要

固体氧化物燃料电池是一种对环境友好并且能量转化效率非常高的新型发电装置。因为它的诸多优点，自九十年代以来，全球掀起了对SOFC的研究热潮。固体氧化物燃料电池在燃料电池中属于第三代燃料电池，它作为一种全固态的电化学发电装置，具有许多优点，例如：功率密度高，环境污染小，燃料适用范围广。因此，固体氧化物燃料电池在当今引起了研究重视，并且被认为是可以在未来和质子交换膜燃料电池一样被广泛应用在生产生活中的一类燃料电池。

在移动电源领域，近年来，固体氧化物燃料电池的应用也更加普及，特别是在新能源汽车的应用方面，固体氧化物燃料电池常作为辅助电源使用，主电源的应用研究也在如火如荼地进行。固体氧化物燃料电池由于它的高的能量密度，机械强度以及燃料气适应性强的优点，正在推动燃料电池汽车的市场化进程。

固体氧化物燃料电池内部存在着许多物理场耦合作用，气流场，电流场，压力场，温度场的等都对燃料电池的输出电学性能起着至关重要的作用，因此对固体氧化物燃料电池的流场进行管理研究十分必要。但是SOFC的工作温度非常高，一般范围在600℃至1000℃，在五大燃料电池中是最高的。因为它的高温工作环境，电池内部的电化学反应较快，离子的传导得到了促进。但是高温也存在一定的弊端，由于电池的高温以及密封工作环境，使得电池的内部反应过程以及电学性能难以通过实验研究得到，并且实验研究需要耗费大量的时间。因此在对固体氧化物燃料电池流场进行研究时，建模仿真成为一种应用很广泛的手段。

本文首先对固体氧化物燃料电池进行了理论分析，结合了热力学和基础电化学知识，对燃料电池能斯特电势进行分析，对浓差极化，欧姆极化和活化极化的成因以及对电池电学性能进行描述，并对其数学函数模型进行理论分析。燃料电池内部的物理场研究方面，本文采用了多物理场耦合软件COMSOL对单电池进行网格离散化以及数值模拟仿真研究。燃料电池模型选用应用比较广泛的平板式燃料电池，燃料气为氢气。以工程流体力学和电化学基础为依据，建立连续性方程，动量传输方程，组分守恒方程以及二次电流分布模型。综合考虑了燃料气-氧化气的正逆向通气，进气速度场以及进气组分浓度，电解质厚度对电池内部组分传输，输出功率密度，电流密度，极化损耗以及气体利用率的影响。对各工况下的燃料电池输出性能进行综合分析比较，总结出最佳燃料电池工作的流场条件，对具体实验研究具有一定指导意义。

关键词：固体氧化物燃料电池；电化学；流体力学；多物理场耦合

Abstract

Solid oxide fuel cells are a new type of power generation device that is environmentally friendly and has very high energy conversion efficiency. Because of its many advantages, since the 1990s, there has been a global upsurge of research on SOFC. The solid oxide fuel cell belongs to the third generation fuel cell in the fuel cell. As an all-solid electrochemical power generation device, the solid oxide fuel cell has many advantages, such as high power density, small environmental pollution, and wide range of fuel application. Therefore, the solid oxide fuel cell has attracted research attention today, and is considered to be a type of fuel cell that can be widely used in production and life as a proton exchange membrane fuel cell in the future.

There are many physical field coupling effects in the solid oxide fuel cell. The airflow field, current field, pressure field, and temperature field all play a vital role in the output electrical performance of the fuel cell. Therefore, it is necessary to study the flow field of solid oxide fuel cells. However, the operating temperature of SOFC is very high, generally ranging from 600°C to 1000°C, which is the highest among the five major fuel cells. Because of its high temperature working environment, the electrochemical reaction inside the battery is faster and the conduction of ions is promoted. However, high temperatures also have certain disadvantages. Due to the high temperature of the battery and the sealed working environment, the internal reaction process and electrical properties of the battery are difficult to obtain through experimental research, and the experimental research requires a lot of time. Therefore, numerical simulations have become a widely used method when studying the flow field of solid oxide fuel cells.

In this paper, the theoretical analysis of the solid oxide fuel cell is firstly carried out, and the thermodynamics and basic electrochemical knowledge are combined to analyze the energy potential of the fuel cell. This paper describes the causes of concentration polarization, ohmic polarization and activation polarization, and describes the electrical properties of batteries, and analyzes the mathematical function model. For the research of the physics inside the fuel cell, the multi-physics coupling software COMSOL was used to perform grid discretization and numerical simulation of the single cell. The fuel cell model uses a flat fuel cell and the fuel gas is hydrogen. Based on engineering fluid mechanics and electrochemistry, the continuity equation, momentum transfer equation, component conservation equation and secondary current distribution model were established. The effects of the positive and negative ventilation of the fuel gas-oxidation gas, the inlet velocity field, the concentration of the inlet gas components, and the thickness of the electrolyte on the internal component transmission, output power density, current density, polarization loss, and gas utilization efficiency are considered. Comprehensive analysis and comparison of the fuel cell output performance under various operating conditions, summed up the optimal flow field conditions for fuel cell work, and has certain guiding significance for the specific experimental study.

Key Words：Solid oxide fuel cells; Electrochemistry; Fluid mechanics; Multiphysics coupling; Numerical simulation

目 录

第1章 绪论 1

1.1 研究背景及意义 1

1.1.1 燃料电池研究背景 1

1.1.2 固体氧化物燃料电池研究意义 3

1.2 国内外研究现状 4

1.2.1 国外研究现状 4

1.2.2 国内研究现状 7

1.3 本论文的选题意义以及主要研究内容 8

1.3.1 选题意义 8

1.3.2 本文主要研究内容 9

第2章 固体氧化物燃料电池介绍 10

2.1 固体氧化物燃料电池概述 10

2.2 固体氧化物燃料电池的分类与组成 11

2.2.1 固体氧化物燃料电池的分类 11

2.2.2 固体氧化物燃料电池的组成 13

2.3 固体氧化物燃料电池的工作原理 14

2.4 本章小结 16

第3章 固体氧化物燃料电池理论基础 17

3.1 燃料电池电势基础 17

3.1.1 电池的电压与电动势 17

3.1.2 吉布斯自由能与能斯特方程 17

3.2 SOFC电池极化分析 20

3.2.1 极化的概念 20

3.2.2 活化极化 21

3.2.3 欧姆极化 22

3.2.4 浓差极化 22

3.3 电池的效率研究 23

3.3.1 燃料电池理想效率 23

3.3.2 燃料电池的实际效率 23

3.4 本章小结 23

第4章 固体氧化物燃料电池流场建模 25

4.1 几何模型与网格划分 25

4.1.1 单流道几何模型 25

4.1.2 网格划分 26

4.2 单流道燃料电池参数与工况 27

4.3 理论数学模型与方程 28

4.3.1 质量守恒方程 28

4.3.2 动量守恒方程 29

4.3.3 组分守恒方程 29

4.3.4 二次电流分布方程 30

4.4 本章小结 31

第5章 流场仿真结果与分析 32

5.1 单电池燃料气-氧化气流动正逆方向 32

5.1.1 电流密度对比研究 32

5.1.2 气体组分对比研究 34

5.1.3 功率密度对比研究 36

5.1.4 极化现象对比研究 37

5.1.5 同逆向通气现象总结 38

5.2 燃料气-氧化气进气速度 38

5.2.1 不同进气速度下电池输出电压对比研究 38