燃料电池及其发展概况

概述了燃料电池原理并计算了氢氧型燃料电池可逆条件下电池电压和效率。介绍了国外熔融碳酸盐型燃料电池（MCFC）、固体氧化物型燃料电池（SOFC）和固体高分子型燃料电池（PEFC）的最新进展，国内的发展状况。     

管式SOFC热电特性的三维数值研究

1前言固体氧化物燃料电池(SOFC)作为一种高效、低排放的先进发电方式,日益受到了人们的关注。其几何结构主要有板式、管式和单一整体形式。管式SOFC具体结构紧凑、能承受较高的工作压力等特点,目前,美国西屋公司开发的管式SOFC已经有了示范性工程。SOFC的平均工作温度一般在800     

连接体结构对固体氧化物燃料电池性能影响的数值分析

固体氧化物燃料电池（SOFC）中连接体结构对电池性能有重要影响。为探究连接体结构对固体氧化物燃料电池性能的影响，建立了传统直通、圆柱形、矩形和凹形4种不同连接体结构SOFC的三维数值模型，并对其流体流动、组分传递、电化学反应和固体流体传热的多物理场耦合过程进行了数值模拟。结果表明，在一定条件下，圆柱形、矩形和凹形连接体结构有利于电池中气体的传输，使电池的电流密度和输出功率均有所提升，其中凹形连接体结构的提升效果最明显，圆柱形、矩形连接体结构的次之。不同孔隙率下圆柱形、矩形和凹形连接体结构均优于传统直通连接体结构，在阴极孔隙率较小时其优势更加明显。     

以合成气为燃料的SOFC多物理场传递过程数值分析

固体氧化物燃料电池(SOFC)内存在复杂的多物理场传递过程,这些过程对电池的性能具有重要的影响.以某实际生产的SOFC为对象,建立了其三维模型,模型描述了以合成气为燃料时其内部发生的传质、传热、化学及电化学反应等多物理场过程.根据模拟结果,给出了两种合成气组分下电池内温度、气体组分、化学反应速率以及电流密度等参数的分布...     

固体氧化物燃料电池技术进展及其在汽车上的应用

固体氧化物燃料电池（SOFC）采用的是全固体的电池结构，可进行甲烷、燃料油（汽油、柴油）的内部重整、适用于多种燃料气，从而解决了燃料的供应问题？固体氧化物燃料电池不但可以应用于固定电站。在电动车方面也有很好的发展前景。较详细地介绍了SOFC在汽车方面的应用以及为了实现这一技术的产业化所必须解决的关键问题。     

板式固体氧化物燃料电池积碳特性实验

固体氧化物燃料电池(SOFC)阳极积碳是制约其高效稳定运行的瓶颈问题,文中回顾了国内外学者在实验领域对SOFC积碳问题的研究进展,并指出研究积碳产生速率数学模型的意义.搭建了由气路管道,气体流量控制器,开启式真空气氛管式电加热炉等仪器设备组成的固体氧化物燃料电池积碳测试实验台;介绍了实验用片状阳极材料的制备,以及积碳实...     

平板状固体氧化物燃料电池的数值模拟

利用流体力学计算软件FLUENT建立平板状固体氧化物燃料电池（SOFC）三维数值模型，研究在不同操作条件和支撑形式下，活化极化、欧姆极化、浓度极化对SOFC性能的影响。在多孔电极中的气体流动符合达西定律的前提下，为满足不同的多孔电极设计，综合考虑了摩尔扩散和Knudsen扩散。另外还考虑了电池电化学反应热对欧姆极化的影响。分析结果表明，阴极和阳极支撑固体氧化物燃料电池具有较低的操作温度和较好的输出特性。     

新型平板式固体氧化物燃料电池的开发和性能分析

利用商业数值分析软件和试验获得的电池各部件材料性能数据,改进了用于分析固体氧化物燃料电池(SOFC)单电池内部复杂物理过程的软件包.应用该软件包,得到了设计的新型高效平板式SOFC单电池内部各气体组分浓度、温度、电势、电流及电流密度等参数的分布规律.分析结果表明:在高燃料利用率情况下,阳极内组分扩散引起的浓度极化损失是影响电池性能的重要因素之一.该新型结构电池可有效改善电池的密封性,但其电解质需要较高的最大离子传导率.     

PV-SOFC联合发电系统的建模及仿真

基于光伏-固体氧化物燃料电池联合发电系统的匹配测试、特性模拟对其设计及应用的重要作用,分析了光伏电池、固体氧化物燃料电池(SOFC)、电解槽、DC/DC变换器等各子系统的特性并在Matlab环境下搭建相应模型,将各子系统模型集成该联合发电系统的Matlab/simulink模型并进行了仿真结果验证.结果表明,光伏-固体氧化物燃料电池实用性强、效率高.     

固体氧化物燃料电池双极板材料发展综述

固体氧化物燃料电池(SOFC)作为第三代燃料电池,以其能量转换效率高、燃料适用范围广、对环境友好、全固态等诸多优势而备受关注.双极板(又称连接体)作为固体氧化物燃料电池的重要组成部分之一,在SOFC电池堆中起到串并联单体电池并隔绝燃料气体与空气的作用,对电池性能及商用成本有很大影响.不同材料的双极板存在不同的性能问题,主要都集中在导电性能、抗氧化性能、化学稳定性及热膨胀系数是否匹配等方面.本文综述了传统陶瓷材料、合金材料、新型陶瓷材料、复合材料双极板的发展历程及最新研究进展,并着重介绍了组分优化设计及表面改性(涂覆活性氧化物涂层、稀土钙钛矿涂层及尖晶石涂层等)两种方式对于合金材料抑制镉元素向外扩散的能力、抗氧化性及导电性的改善.综合分析表明,通过组分优化设计和表面改性弥补合金作为双极板材料的性能缺陷,尝试制备新型陶瓷材料或复合材料等途径,有望获得高性能、低成本的双极板材料,从而实现SOFC的大规模商业化应用.     

天然气重整SOFC/MGT混合分布式供能系统性能分析

针对固体氧化物燃料电池(SOFC)与微型燃气轮机(MGT)构成的混合分布式供能系统,首先建立了一种管式SOFC准二维数值模型,优化了辐射计算,提高了热传递模型的准确性;考虑了CO及H2同时作为燃料参加电化学反应,并完善了损失计算模型;最后采用所发展的系统性能预测模型,分别在内部重整和外部重整情况下,预测比较了两种SOFC/MGT混合系统的性能,结果表明外部重整系统在系统输出功率、CO2排放以及热应力分布方面都比内部重整系统具有优势,然而这种轻微的优势是需要额外增加外部重整器的设备投资换取的。     

A mathematical model of a tubular solid oxide fuel cell with specified combustion zone

A numerical model has been developed to simulate the effect of combustion zone geometry on the steady state and transient performance of a tubular solid oxide fuel cell (SOFC). The model consists of an electrochemical submodel and a thermal submodel. In the electrochemical model, a network circuit of a tubular SOFC was adopted to model the dynamics of Nernst potential, ohmic polarization, activation polarization, and concentration polarization. The thermal submodel simulated heat transfers by conduction, convention, and radiation between the cell and the air feed tube. The developed model was applied to simulate the performance of a tubular solid oxide fuel cell at various operating parameters, including distributions of circuits, temperature, and gas concentrations inside the fuel cell. The simulations predicted that increasing the length of the combustion zone would lead to an increase of the overall cell tube temperature and a shorter response time for transient performance. Enlarging the combustion zone, however, makes only a negligible contribution to electricity output properties, such as output voltage and power. These numerical results show that the developed model can reasonably simulate the performance properties of a tubular SOFC and is applicable to cell stack design.     

Mechanistic modelling of a cathode-supported tubular solid oxide fuel cell

A two-dimensional mechanistic model of a tubular solid oxide fuel cell (SOFC) considering momentum, energy, mass and charge transport is developed. The model geometry of a single cell comprises an air-preheating tube, air channel, fuel channel, anode, cathode and electrolyte layers. The heat radiation between cell and air-preheating tube is also incorporated into the model. This allows the model to predict heat transfer between the cell and air-preheating tube accurately. The model is validated and shows good agreement with literature data. It is anticipated that this model can be used to help develop efficient fuel cell designs and set operating variables under practical conditions. The transport phenomena inside the cell, including gas flow behaviour, temperature, overpotential, current density and species concentration, are analysed and discussed in detail. Fuel and air velocities are found to vary along flow passages depending on the local temperature and species concentrations. This model demonstrates the importance of incorporating heat radiation into a tubular SOFC model. Furthermore, the model shows that the overall cell performance is limited by O₂ diffusion through the thick porous cathode and points to the development of new cathode materials and designs being important avenues to enhance cell performance.     

Numerical study of a flat-tube high power density solid oxide fuel cell: Part I. Heat/mass transfer and fluid flow

The flat-tube high power density (HPD) solid oxide fuel cell (SOFC) is a new design developed by Siemens Westinghouse, based on their formerly developed tubular type SOFC. It has increased power density, but still maintains the beneficial feature of secure sealing of a tubular SOFC. In this paper, a three-dimensional numerical model to simulate the steady state heat/mass transfer and fluid flow of a flat-tube HPD-SOFC is developed. In the numerical computation, governing equations for continuity, momentum, mass, and energy conservation are solved simultaneously. The highly coupled temperature, concentration and flow fields of the air stream and the fuel stream inside and outside the different chambers of a flat-tube HPD-SOFC are investigated. The variation of the temperature, concentration and flow fields with the current output is studied. The heat/mass transfer and fluid flow modeling and results will be used to simulate the overall performance of a flat-tube HPD-SOFC, and to help optimize the design and operation of a SOFC stack in practical applications.     

Performance analysis of hybrid solid oxide fuel cell and gas turbine cycle (part I): Effects of fuel composition on output power

In this paper, the model of hybrid solid oxide fuel cell (SOFC) and gas turbine (GT) cycle is applied to investigate the effects of the inlet fuel type and composition on the performance of the hybrid SOFC–GT cycle. The sensitivity analyses of the impacts of the concentration of the different components, namely, methane, hydrogen, carbon dioxide, carbon monoxide, and nitrogen, in the inlet fuel on the performance of the hybrid SOFC–GT cycle are performed. The simulation results are presented with respect to a reference case, when the system is fueled by pure methane. Then, the performance of the hybrid SOFC–GT system when methane is partially replaced by each component within a corresponding range of concentration with an increment of 5% at each step is investigated. The results point out that the output powers of the SOFC, GT, and cycle as a whole decrease sharply when methane is replaced with other species in majority of the cases.     

Modeling of gas transport through a tubular solid oxide fuel cell and the porous anode layer

A design model is a necessary tool to understand the gas transport phenomena that occurs in a tubular solid oxide fuel cell (SOFC). This paper describes a computational model, which studies the gas flow through an anode-supported tubular SOFC and the subsequent diffusion of gas through its porous anode. The model is a numerical solution for the gas flow through a plug flow reactor with a diffusion layer, which includes the activation, ohmic, and concentration polarizations. Gas diffusion is modeled using the dusty-gas equations which include Knudsen diffusion. Mercury intrusion porosimetry (MIP) is used to experimentally determine micro-structural parameters such as porosity, tortuosity and effective diffusion coefficients, which are used in the diffusion equations for the porous anode layer. It was found that diffusion in the anode plays a key role in the performance of a tubular SOFC. The concentration gradient of hydrogen and water results in a lower concentration of hydrogen and a higher concentration of water at the reactive triple phase boundary (TPB) than in the fuel stream which both lead to a lower cell voltage. The gas diffusion determines the limiting current density of the cell where a higher concentration drop of hydrogen results in a lower limiting current density. The model validates well with experimental data and is used to improve micro-tubular solid oxide fuel cell designs.     

Numerical analysis of start-up operation of a tubular solid oxide fuel cell

The purpose of the current study is to numerically predict the start up behavior of a tubular solid oxide fuel cell (SOFC) using a 2-D transient model. The developed model provides the transient response of the start-up mode as well as the steady state operation of the SOFC. A code based on finite volume method is utilized to solve the transient nonlinear transport equations of the cell (momentum, species and energy equations). To account for the Ohmic losses and Joule heating of the current that passes through the cell body, a discretized network circuit is adopted. The local electrochemical parameters are calculated based on the local pressure, temperature, and concentrations of the species. At each time step an iterative procedure is used to solve the electrochemical, electrical and transport equations simultaneously. The model predicts the cell output voltage, the local EMF and the state variables (pressure, temperature and species concentration) during the start up. It also predicts the cell heat-up rate for hot input gases as well as the start up time of the SOFC. The results show that the gases mass flow rate and temperature affect the heat-up rate. Also during the start-up, the cell electrical response is about 2.5 times quicker than the cell temperature response. The start-up time for the cell output voltage is about 50 min.     

Performance analysis of a SOFC button cell using a CFD model

In this study, a 2-D numerical model is investigated to predict and evaluate the performance of an anode-supported SOFC button cell. The flow field is calculated using 2D Navier–Stokes equations. Heat and mass transfer equations are solved to calculate species and temperature distribution in the cell body and in fuel and air channels. The electrical and electrochemical processes are simulated coupled with the heat and mass transfer model. A discretized network circuit is adopted to the cell geometry for considering the ohmic losses and joule heating of the current that passes through the cell body. The model predicts the cell output voltage, the local EMF and the state variables pressure, temperature and species concentrations. The local electrical parameters are calculated based on the local pressure, temperature and concentration of the species. The numerical results are compared with the experimental data and good agreement is observed. The simulation is carried out for different input fuel flow rates and humidification. The results show how the input fuel mass flow rate and humidification level affects the button cell SOFC performance. In addition, influences of the anode thickness on cell performance through the ohmic over potential are investigated.     

Numerical modelling and comparative analysis of direct ammonia fuelled protonic and oxygen- ion conducting tubular solid oxide fuel cell

The main emphasis of this work is developing a 3D numerical model and investigating the performance characteristic of a direct ammonia fuelled protonic-conducting tubular solid oxide fuel cell (NH₃-T–SOFC–H) in comparison with the corresponding hydrogen-fuelled one and direct ammonia feed oxygen -ion conducting tubular solid oxide fuel cell (NH₃-T–SOFC–O) under the same operating parameters and geometrical shape. The findings revealed that NH₃-T–SOFC–H has outstanding performance over T–SOFC–O counterparts at intermediate temperature (973 K) when operated under similar working conditions and geometrical designs. On the other hand the NH₃-T–SOFC–O is promising for higher operating temperatures. The outcomes of the study are also confirmed that the power performance of NH₃-AS-T–SOFC–O is better than the other supports of both electrolytes when the anode electrode is constructed at the outside portion of the tubular cell. Yet, the other remarkable result found in this study is that NH₃– CS- T–SOFC–O has outstanding performance compared to all supports of both electrolytes when the fuel electrode is built in the inner portion of the tube. In addition, the finding indicates that the power performance of ammonia-fuelled tubular cells is strongly influenced by the anode position, operating temperatures, and pressures in both electrolytes yet the effect of cell temperature is more influential in the protonic-conducting cell. It is also observed that the performance of ES-T-SOFC is lower than AS- and CS-T-SOFC in both electrolytes and anode positions.     

Numerical analysis of output characteristics of tubular SOFC with internal reformer

In the solid oxide fuel cell (SOFC) system, the internal reforming of raw fuel will act as an efficient cooling system. To realize this cooling system, a special design of the internal reformer is required to avoid the inhomogeneous temperature distribution caused by the strong endothermic reforming reaction at the entrance of the internal reformer. For this purpose, a tubular internal reformer with adjusted catalyst density can be inserted into the tubular SOFC stack. By arranging this, the raw fuel flows along the axis of the internal reformer to be moderately reformed and returns at the end of the internal reformer as a sufficiently reformed fuel.In this paper, the output characteristics of this configuration are simulated using mathematical models, in which one-dimensional temperature and molar distributions are computed along the flow direction. By properly mounting the catalyst density in the internal reformer, the temperature distribution of the cell stack becomes moderate, and the power generation efficiency and the exhaust gas temperature are higher. Effects of other operating conditions such as fuel recirculation, fuel inlet temperature, air recirculation and air inlet temperature are also examined under the condition where the maximum temperature of the stack is kept at 1300 K by adjusting the air flow rate. Under this condition, these operating conditions exert a considerable effect on the exhaust temperature but have a slight effect on the efficiency.