熔融碳酸盐燃料电池热启动过程的人工神经网络建模

熔融碳酸盐燃料电池(MCFC)是燃料电池研究领域的一个难点,其严格的热启动过程对电池性能和寿命的影响至关重要.针对这一问题,建立了基于人工神经网络的熔融碳酸盐燃料电池热启动过程模型,并详细给出了采用改进BP算法的熔融碳酸盐燃料电池热启动过程的模型结构、算法、训练和仿真.MATLAB仿真结果证明其快速准确,为熔融碳酸盐燃料电池热启动过程的控制提供了实际工程应用模型.     

MCFC热启动过程的人工神经网络建模分析

熔融碳酸盐燃料电池目前是燃料电池研究领域的一个难点，其严格的热启动过程对电池性能和寿命的影响至关重要。针对这一问题，建立了基于人工神经网络的熔融碳酸盐燃料电池热启动过程模型，详细给出了采用改进BP算法的熔融碳酸盐燃料电池热启动过程的模型结构、算法、训练和仿真。MATLAB仿真结果证明其快速准确，为熔融碳酸盐燃料电池热启动过程的控制提供了实际工程应用模型。     

熔融碳酸盐燃料电池发电系统的研究

燃料电池,尤其是熔融碳酸盐燃料电池是本世纪敢有希望的发电技术。在简要叙述了熔融碳酸盐燃料电池发电系统的发电原理后,介绍了熔融碳酸盐燃料电池发电系统的国内外研究现状,给出了天然气外部重整型和内部重整型燃料电池的循环模型。指出熔碳酸盐燃料电池系统开发面临的主要课题。     

底层与顶层MCFC-MGT联合循环系统性能分析

在IPSEpro仿真环境下建立了熔融碳酸盐燃料电池/微型燃气轮机联合循环系统顶层循环和底层循环仿真模型.利用该模型对两种不同型式的联合循环系统在额定工况和变工况下的稳态性能进行了研究,并对两种联合循环系统的主要性能参数进行了对比分析.结果表明:熔融碳酸盐燃料电池/微型燃气轮机顶层联合循环系统具有较高的发电效率,而底层循环具有良好的变负荷特性.     

MCFC-并联TTEG混合系统的性能优化

为有效回收熔融碳酸盐燃料电池产生的余热,提出一种由熔融碳酸盐燃料电池(MCFC)、两级并联温差发电器(TTEG)和回热器组合而成的混合系统模型.考虑MCFC电化学反应中的过电势损失和混合系统中的不可逆损失,通过数值分析得出混合系统的输出功率和效率的数学表达式,获得混合系统的一般性能特征,讨论MCFC电流密度与温差发电器...     

熔融碳酸盐型燃料电池的研究和发展

目前燃料电池被国际公认为是继水力、火力、原子能发电之后的第四代发电系统。燃料电池通常以电解质来命名,分为碱水型、磷酸型、熔盐型、固体高温型等。本文主要对熔融碳酸盐型燃料电池的基本原理、基本结构及各部件制作以及技术现状和应用情况进行简明介绍。一、熔融碳酸盐燃料电池(MUFC)的发展概况燃料电池是将燃料气和氧化气反应的化学能直接变成电能的装置。早在1921年Baur等人就对以熔融碳酸盐作为电解质、氢气和一氧化碳为燃料、空气作为氧化气做成的电池做     

基于AspenPlus的兆瓦级燃料电池分布式发电系统建模及仿真分析

  目的  燃料电池分布式发电技术是适应未来能源低碳化、清洁化、高效化发展趋势的重要应用方向。国内燃料电池电站项目较少,缺乏实际项目经验积累。为了推进燃料电池分布式电站技术的应用,文章概述了国内外应用现状,总结了高温燃料电池的优势与不足,调研了国内燃料电池建设应用案例,并建立了固体氧化物燃料电池与熔融碳酸盐燃料电池发电系统流程。  方法  经过文献调研与实地调研,确定了两种适合建设大型电站的燃料电池分布式发电技术,并利用AspenPlus化工模拟软件建立燃料电池系统流程模型、电化学模型和能量分析模型,并开展系统的性能仿真分析。  结果  分析结果与实际运行结果相吻合,分析预测的系统性能趋势与已有研究相一致。  结论  该仿真方法可用于兆瓦级高温燃料电池分布式发电系统的研究,可为扩大燃料电池应用规模提供数据支持。     

质子交换膜燃料电池经验模型

分析并总结现有PEMFC经验模型相互之间的关系,并运用Saber仿真软件,结合一定的电化学原理和热动力学原理建立一个较为简单的PEMFC经验模型,模拟其稳态和动态特性。结果表明:这些模型能很好地反映实际燃料电池的电气特性,对后级电力电子装置的设计具有重要指导意义。     

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。     

燃料电池发展现状与应用前景

介绍了各种类型燃料电池（碱性燃料电池,熔融碳酸盐燃料电池,固体氧化物燃料电池,磷酸燃料电池及质子交换膜燃料电池）的技术进展,电池性能及其特点。其中着重介绍了当今国际上应用较广泛,技术较为成熟的磷酸燃料电池和质子交换膜燃料电池。对燃料电池的应用前景进行探讨,并对我国的燃料电池研究提出了一些建议。     

Solubility and electrochemical studies of LiFeO2–LiCoO2–NiO materials for the MCFC cathode application

The dissolution of the state-of-the-art lithiated NiO is still considered as one of the main obstacles to the commercialisation of the molten carbonate fuel cell (MCFC). Development of alternative cathode materials has been considered as a main strategy for solving this problem. Ternary compositions of LiFeO₂, LiCoO₂ and NiO are expected to decrease the cathode solubility while ensuring a good electrical conductivity and electrochemical activity towards the oxygen reduction.

In this work, new material compositions in the LiFeO₂–LiCoO₂–NiO ternary system were synthesised using Pechini method and investigating their electrical conductivity by the DC four probe method. Then the influence of the cobalt content in the composition was determined in terms of AC impedance analysis and solubility measurements after 200 h of immersion in Li₂CO₃–Na₂CO₃ at 650 °C. The DC electrical conductivity study reveals the ability of improving the electrical conductivity, adequate for MCFC cathode application, by controlling the Co content of the composition. A special attention was given to the evolution of the open circuit potential as a function of time and to the impedance spectroscopy characterization related to microstructure modifications. Taking into account solubility, electrical conductivity, as well as electrochemical performance in the fuel cell, this study reveals the possibility of using LiFeO₂–LiCoO₂–NiO ternary materials for MCFC cathode.     

Molten Carbonate Fuel Cell electrochemistry modelling

A Fuel Cell (FC) is an electrochemical device which produces electric energy in DC. In order to support design control for the electrical system connected to it, it is necessary to work out a suitable representation of the fast dynamics involved. Therefore, in this work, a mathematical model, based on first principles and including both dynamical equations and algebraic relations, is described for electrochemical reactions, with the related formation of potential differences and anion and cation accumulation phenomena, in a Molten Carbonate Fuel Cell (MCFC). The model is formally consistent and it has been validated against experimental results, such as steady-state power and voltage versus current curves.     

Electrochemical performances of NANOCOFC in MCFC environments

The electrochemical performances of fuel cells using nano-ceria-salt composites electrolyte (NANOCOFC) have been investigated at different temperatures in molten carbonate fuel cell (MCFC) environment. The maximum output power density increased with the temperature, and reached 140 mW/cm² at 650 °C. After operating for 200 h, the open circuit voltage (OCV) can keep the same value and the output power density only deceased 0.08%. It demonstrated that the NANOCOFC possessed the perfect stability of electrochemical performance in the MCFC environment. However, it was found that the output power density of the fuel cell in MCFC environment was much lower than that of fuel cell in SOFC environment. It was implied that the carbonate transfer would hinder the conduction of both proton and oxygen ion, which result in the poor output power density of fuel cells.     

MCFC and microturbine power plant simulation

The consistent problem of the CO₂ emissions and the necessity to find new energy sources, are motivating the scientific research to use high efficiency electric energy production's technologies that could exploit renewable energy sources too. The molten carbonate fuel cell (MCFC) due to its high efficiencies and low emissions seems a valid alternative to the traditional plant. Moreover, the high operating temperature and pressure give the possibility to use a turbine at the bottom of the cells to produce further energy, increasing therefore the plant's efficiencies. The basic idea using this two kind of technologies (MCFC and microturbine), is to recover, via the microturbine, the necessary power for the compressor, that otherwise would remove a consistent part of the MCFC power generated. The purpose of this work is to develop the necessary models to analyze different plant configurations. In particular, it was studied a plant composed of a MCFC 500 kW Ansaldo at the top of a microturbine 100 kW Turbec. To study this plant it was necessary to develop: (i) MCFC mathematical model, that starting from the geometrical and thermofluidodynamic parameter of the cell, analyze the electrochemical reaction and shift reaction that take part in it; (ii) plate reformer model, a particular compact reformer that exploit the heat obtained by a catalytic combustion of the anode and part of cathode exhausts to reform methane and steam; and (iii) microturbine-compressor model that describe the efficiency and pressure ratio of the two machines as a function of the mass flow and rotational regime. The models developed was developed in Fortran language and interfaced in Chemcad^© to analyze the power plant thermodynamic behavior. The results show a possible plant configuration with high electrical and global efficiency (over 50 and 74%).     

Performance model of molten carbonate fuel cell

A performance model of a molten carbonate fuel cell (MCFC), an electrochemical energy conversion device for electric power generation, is discussed. The presumptive ability of the MCFC model is improved and the impact of MCFC characteristics in fuel cell system simulations is investigated. Basic data are obtained experimentally by single-cell tests. A correlation formula based on the experimental data is derived for the cell voltage and the oxygen and carbon dioxide partial pressures. Three types of MCFC systems are compared. With regard to fuel utilization, system characteristics using the proposed correlation are very similar to those obtained using a previous model. However, the amount of decrease predicted by the proposed model with respect to system efficiency is larger than that obtained by the previous model at high air utilization     

Analysis of a molten carbonate fuel cell: Numerical modeling and experimental validation

A detailed dynamic model incorporating geometric resolution of a molten carbonate fuel cell (MCFC) with dynamic simulation of physical and electrochemical processes in the stream-wise direction is presented. The model was developed using mass and momentum conservation, electrochemical and chemical reaction mechanisms, and heat-transfer. Results from the model are compared with data from an experimental MCFC unit. Furthermore, the model was applied to predict dynamic variations of voltage, current and temperature in an MCFC as it responds to varying load demands. The voltage was evaluated using two different approaches: one applying a model developed by Yuh and Selman [C.Y. Yuh, J.R. Selman, The polarization of molten carbonate fuel cell electrodes: I. Analysis of steady-state polarization data, J. Electrochem. Soc. 138 (1991) 3642–3648; C.Y. Yuh, J.R. Selman, The polarization of molten carbonate fuel cell electrodes: II. Characterization by AC impedance and response to current interruption, J. Electrochem. Soc. 138 (1991) 3649–3655] and another applying simplified equations using average local temperatures and pressures. The results show that both models can be used to predict voltage and dynamic response characteristics of an MCFC and the model that uses the more detailed Yuh and Selman approach can predict those accurately and consistently for a variety of operating conditions.     

Comparison by the use of numerical simulation of a MCFC-IR and a MCFC-ER when used with syngas obtained by atmospheric pressure biomass gasification

In order to realize biomass potential as a major source of energy in the power generation and transport sectors, there is a need for high efficient and clean energy conversion devices, especially in the low-medium range suiting the disperseness of this fuel. Large installations, based on boiler coupled to steam turbine (or IGCC), are too complex at smaller scale, where biomass gasifiers coupled to ICEs have low electrical efficiency (15-30%) and generally not negligible emissions.This paper analyses new plants configurations consisted of Fast Internal Circulated Fluidized-Bed Gasifier, hot-gas conditioning and cleaning, high temperature fuel cells (MCFC), micro gas turbines, water gas shift reactor and PSA to improve flexibility and electric efficiency at medium scale. The power plant feasibility was analyzed by means of a steady state simulation realized through the process simulator Chemcad in which a detailed 2D Fortran model has been integrated for the MCFC. A comparison of the new plant working with external (MCFC-ER) and internal (MCFC-IR) reforming MCFC was carried out. The small amount of methane in the syngas obtained by atmospheric pressure biomass gasification is not enough to exploit internal reforming cooling in the MCFC. This issue has been solved by the use of pre-reformer working as methanizer upstream the MCFC. The results of the simulations shown that, when MCFC-IR is used, the parameters of the cell are better managed. The result is a more efficient use of fuel even if some energy has to be consumed in the methanizer. In the MCFC-IR and MCFC-ER configurations, the calculated cell efficiency is, respectively, 0.53 and 0.42; the electric power produced is, respectively, 236 and 216 kW_e, and the maximum temperature reached in the cell layer is, respectively, 670 °C and 700 °C. The MCFC-ER configuration uses a cathode flowrate for MCFC cooling that are 30% lower than MCFC-IR configuration. This reduces pressure drop in the MCFC, possible crossover effect and auxiliaries power consumption. The electrical efficiency for the MCFC-IR configuration reaches 38%.     

Simulation of the performance for the direct internal reforming molten carbonate fuel cell. Part II: comparative distributions of reaction rates and gas compositions

This study examined the distributions of the three reaction rates and the compositions of the gases at each point of the unit cell in DIR‐MCFC using a numerical simulation. The electrochemical reaction rates at the anode gas entering position were almost two times faster than those at the anode gas outlet position and most of the feeding CH₄ reacted in the region from the position x=0 to the position x=0.3. In addition, the water–gas shift reaction became faster from near the half position of the unit cell to the gas outlet position. Therefore, in the rear position of the unit cell, the steam reforming reaction played an important role as a supplementary reaction for providing the H₂ needed in the electrochemical reaction. The rates of the two catalytic reactions in the case without the electrochemical reaction were relatively slower than those in the DIR‐MCFC. Unlike the distributions of temperature, the current density, gas compositions and the reactions rates at each point of the DIR‐MCFC cell, the exit gas compositions from the simulation in particular could be comparative to those of the experimental results. Although there was an approximately 10% difference between both of them, the extent of the difference was considered to be reasonable for this simulation considering the experimental values that could be included in this simulation such as the lower conversion of the reactions, the lower current density and any other values. Copyright © 2005 John Wiley & Sons, Ltd.