Numerical Simulation of Dynamic Performance of the Molten Carbonate Fuel Cell

A three dimension of dynamic mathematical model of the molten carbonate fuel cell is established,in which the heat generation, mass transfer and electrochemical characteristics are described. The performance of the fuel cell including the distributions of the temperature and the velocity is predicted numerically. Then the experimental data including the output performance of the fuel cell generation system and the temperature distributions are compared. The numerical results are in agreement with the experiment results.

Development and Experimental Research of kW-scale Molten Carbonate Fuel Cells

A kW-scale molten carbonate fuel cells stack was developed and 800-hours’ operating test and performance experimental research had been done. Utilizing domestic materials completely, we developed NiO cathode and Ni-Al anode with the active area of 336cm 2 and Υ-LiAlO 2 electrolyte tile and bipolar plate with the area of 900cm 2. The stack was composed of thirty cells, with 62%Li 2CO 3+38%K 2CO 3 as its electrolyte. During the 800 hours’ continuous operating, the performance of the stack was stable. With 99.7%(mole fraction) H 2 as fuel and O 2 from air as oxidant, the average operating voltage of a cell was about 0.72 V. The maximal current density attained to 165mA/cm 2, and the maximal output power attained to 1080 Watt. The whole performance of the stack approached to the international level in the early 90’s. This paper gives the main works and experiments results.

Daily Operation Optimization of a Residential Molten Carbonate Fuel Cell Power System Using Genetic Algorithm

To decrease the cost of electricity generation of a residential molten carbonate fuel cell （MCFC） power system, multi-crossover genetic algorithm （MCGA）, which is based on ＂multi-crossover＂ and ＂usefulness-based selection rule＂, is presented to minimize the daily fuel consumption of an experimental 10kW MCFC power system for residential application. Under the operating conditions obtained by MCGA, the operation constraints are satisfied and fuel consumption is minimized. Simulation and experimental results indicate that MCGA is efficient for the operation optimization of MCFC power systems.

Study and performance test of 10 kW molten carbonate fuel cell power generation system

The use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide.This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell.The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy.The results show that the pore size of the key electrode material is 6.5 lm and the matrix material is a-LiAlO_(2).Experimentally,the open circuit voltage of the single cell was found to be 1.23 V.The current density was greater than 100 mA/cm^(2)at an operating voltage of 0.7 V.The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm^(2)and achieved an open circuit voltage of greater than 85 V.The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V.The influence and long-term stable operation of the stack were also analyzed and discussed.The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.

Nonlinear modeling of molten carbonate fuel cell stack and FGA-based fuzzy control

To improve the performance of fuel cells, the operating temperature of molten carbonate fuel cell (MCFC) stack should be controlled within a specified range. In this paper, with the RBF neural network’s ability of identifying complex nonlinear systems, a neural network identification model of MCFC stack is developed based on the sampled input-output data. Also, a novel online fuzzy control procedure for the temperature of MCFC stack is developed based on the fuzzy genetic algorithm (FGA). Parameters and rules of the fuzzy controller are optimized. With the neural network identification model, simulation of MCFC stack control is carried out. Validity of the model and the superior performance of the fuzzy controller are demonstrated.

MICROSTRUCTURE CHARACTERIZATION OF LiCoO_2 COATINGS FOR MOLTEN CARBONATE FUEL CELLS COMPONENTS

The sol-gel process, sing aqueous solutions, is used for dip coating ontosubstrates of 316L stainless steel. A suitable coating of Li CoO_2 is achieved by varying thethickness and heat treating at 650 deg C for 3 h. Thermal analysis, X-ray diffraction analysis andSEM are carried out to characterize the microstructure of the coatings. The results show that thecoating transforms from an amorphous gel to crystalline phases above 350 deg C, and show a porousstructure. The phase transition mechanism is discussed.

Advance on Molten Carbonate Fuel Cell and Research on Some Key Problems

The paper is a summary of researches on molten carbonate fuel cell. On the same time, several key technology difficulties are discussed. Combining with our recent studies, the accessements to these problems are given out and they will be references for future works.

Performance Evaluation of a Molten Carbonate Fuel Cell-Graphene Thermionic Converter-Thermally Regenerative Electrochemical Cycles Hybrid System

A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed.

Hardware Materials in Molten Carbonate Fuel Cell:A Review

The high-temperature molten carbonate fuel cell is an ultra-clean and highly efficient power generator. It is operated at - 550-650 ℃, which is considered optimal in facilitating fast fuel cell reaction kinetics, utilizing waste heat efficiently, and allowing use of commercial construction materials. Commercial MW-size （mega watt） power plants of FuelCell Energy products have already been deployed worldwide. Metallic hardware materials are extensively utilized and may experience high-temperature reducing and oxidizing atmospheres in the presence of molten alkali carbonate electrolyte. Material selections are founded on many decades of focused research and development and field experience. Results to date show that the baseline stack module materials meet 5-year life goal and BOP （balance of plant） construction materials meet 20-year life goal. Material durability is well understood, and solutions are available to further extend the durability. This paper will review hardware materials experience and development approaches that would further reduce cost and extend life.

Multi-objective optimization of molten carbonate fuel cell system for reducing CO2 emission from exhaust gases

The aim of this paper is to investigate the implementation of a molten carbonate fuel cell （MCFC） as a CO2 separator. By applying multi-objective optimization （MOO） using the genetic algorithm, the optimal values of operating load and the corresponding values of objective functions are obtained. Objective functions are minimiza- tion of the cost of electricity （COE） and minimization of CO2 emission rate. CO2 tax that is accounted as the pollution-related cost, transforming the environmental objective to the cost function. The results show that the MCFC stack which is fed by the syngas and gas turbine exhaust, not only reduces CO2 emission rate, but also produces electricity and reduces environmental cost of the system.

Anodic Oxidation of Nickel in Molten(Li_(0.62),K_(0.38))_2CO_3

The anodic oxidation of nickel in molten (Li 0.62 ,K 0.38 ) 2CO 3 was investigated by means of cyclic voltammetry, X ray diffraction and X ray photoelectron spectroscopy. The results indicate that two reactions are involved in the anodic process: one is Ni+O 2- =NiO+2e -, the other reaction is Ni(Ⅱ)=Ni(Ⅲ)+e -.

二元碳酸熔盐在氧化镍表面热物性的分子动力学模拟

采用分子动力学模拟方法,研究了高温下碳酸钠、碳酸钾二元熔盐与氧化镍板的界面体系。研究得到了界面热阻、热导率和黏度等热物性随温度的变化规律,对比了不同温度下均相熔盐材料和界面处熔盐材料的热物性的差异,并且通过密度分布和径向分布函数揭示了热物性发生变化的微观机制。模拟结果显示:温度升高时,熔盐离子间距离增加,范德华力和库仑力相互作用减弱,使得离子间能量传递更加困难,界面热阻、熔盐热导率均下降;同时,熔盐黏度也因为相互作用减弱,熔盐离子自身振动能量增加、运动趋向增强而下降。

熔融碳酸盐燃料电池隔膜用LiAlO_2制备

将Al2O3和Li2CO3混合，600～700℃高温焙烧制备熔融碳酸盐燃料电池隔膜用LiAlO2粉体．工业生产Al2O3颗粒粒度和堆密度大，制得的LiAlO2粉体较粗；有机金属化合物水解再脱水制备的Al2O3颗粒粒度和堆密度小，制得的LiAlO2粉体细．将LiAlO2与一定量的水溶性粘合剂和增塑剂混合，液压成膜，将膜与烧结Ni电极组装成电池，电池性能良好．

熔融碳酸盐燃料电池动态特性的研究

基于能量守恒、质量平衡原理和热力学特性,提出了熔融碳酸盐燃料电池的数学模型,该模型考虑了电解质基块内的质量传递,以及质量传递对燃料电池内部热力学特性的影响,采用加权残差(MWR)数值方法和Matlab环境的系统函数化解偏微分方程组并建立动态仿真模型。仿真表明燃料电池内部各点的温度有较大的差异,随着燃料和氧化剂量的变动(增加),电极-电解质的温度增加,而氧化剂流的温度有所下降。 模型的物理参数是从某燃料电池研究所1.5kW熔融碳酸盐燃料电池获得。

熔融碳酸盐燃料电池单体传热传质数值模拟

在分析熔融碳酸盐燃料电池性能的基础上 ,考虑了电池内的电化学反应、传热传质及电压———电流关系等影响因素 ,提出一套计算稳态条件下熔融碳酸盐燃料电池的温度与电流密度分布的数学模型。并利用它对不同气流方式 (叉流、顺流和逆流等 )的电池分别做了计算。

高温燃料电池—燃气轮机混合发电系统性能分析

针对高温燃料电池系统的高效率、环保性以及排气废热的巨大利用潜能 ,将其与燃气轮机组成混合装置进行发电是未来分布式发电的一种极有前景的方案。文中对高温燃料电池及混合循环系统作了简介 ,并对两种典型的高温燃料电池 -燃气轮机混合循环发电系统进行了性能分析 ,这将为我国高温燃料电池 -燃气轮机混合循环系统的研制提供参考。

熔融碳酸盐燃料电池-燃气轮机混合动力系统特性分析

文中研究了由熔融碳酸盐燃料电池(MCFC)和燃气轮机组成的混合动力系统。在设计点工况下,MCFC电堆的发电量占系统总发电量的80%,剩下20%的电量由燃气轮机提供。文章在混合动力系统动态数学模型的基础上,结合系统运行的具体过程,通过计算分析,对混合动力系统的动态特性进行了研究。结果表明:当混合动力系统的供给燃料流量变化时,混合动力系统内部各参数均会发生显著的动态变化,从而影响混合动力系统中各部件的运行性能,导致混合动力系统的效率下降。此外,由于各部件之间复杂的相互作用,混合动力系统的负荷响应速度较慢。研究结果还表明,由于供给燃料发生变化而引起的燃气轮机转速的改变,有利于改善混合动力系统的变工况性能。

不同工作条件下的熔盐燃料电池性能

以多孔镍板作电极，以带铸法制备的ＬｉＡｌＯ２无机膜作电池隔膜，组装成了电极面积２８ｃｍ２的小型熔融碳酸盐燃料电池，考察了各种工作条件对电池性能的影响。试验结果表明，随气体压力和工作温度提高，电池性能增加。但高温下电池材料腐蚀现象加剧。另外气体压力增加使ＮｉＯ阴极在电解质中的溶解加快，因此为保证一定的电池寿命，工作气体压力和温度不可提高过大，必须控制在一定的范围以内。

氯化物法制备MCFC隔膜用α-LiAlO_2细料的研究

用氯化物法制得α－ＬｉＡｌＯ２细料．两种反应物料分别在６５０℃和５５０℃反应１ｈ，生成α－ＬｉＡｌＯ２．经过水洗等，产生水合作用，生成水合物（ＬｉＡｌＯ２）２·５Ｈ２Ｏ．此水合物失水后，又变为α－ＬｉＡｌＯ２细料．其粒度分别为０．３３μｍ和０．４５μｍ．反应物的粒度和性质及反应温度等对产物α－ＬｉＡｌＯ２粒度均有一定影响．在本方法中，吸入反应机理仍起主要作用．以此细和粗α－ＬｉＡｌＯ２粉料为原料，用流铸法制得电池隔膜．用此隔膜和两张烧结多孔Ｎｉ板组装的电池在２００ｍＡ／ｃｍ２放电时，输出电压为０．８５Ｖ．６次再起动。

熔融碳酸盐燃料电池隔膜及单电池寿命

采用数学模型推算了熔融碳酸盐燃料电池隔膜寿命,并进行了单电池运行稳定性试验。从电池隔膜阻气能力及离子传输能力两方面,提出以其最大阻气压力差Δp≥0.1MPa,孔隙率满足40%≤η≤70%作为其寿命指标。通过电池最大孔径测试法和隔膜模拟烧结孔隙率测试法,建立数学模型,推算出烧结时间为40000h所对应的隔膜最大孔径为0.9332μm,孔隙率为66.7%,皆小于其寿命指标值,这也说明,隔膜寿命超过40000h。单电池1000h寿命试验结果表明,以H2作燃料,电池性能稳定;以模拟煤气作燃料,电池性能快速衰减,主要由所发生的副反应引起。