基于生态学准则对MCFC/AR混合系统的优化分析

基于生态学准则对稳定状态下运行的熔融碳酸盐燃料电池(MCFC)与吸收式制冷机(AR)组成的混合系统进行优化,考虑系统存在的电化学和热力学不可逆性,导出混合系统等效输出功率、效率以及生态学性能系数(ECOP)的表达式。应用数值模拟分析混合系统性能,得到功率密度、效率以及ECOP分别与电流密度的基本关系,从而确定工作参数的优化区间。结果表明:混合系统运行时的输出功率和效率相比于燃料电池单独运行时有所提升,并且通过生态学优化能得到更为精确的优化工作区间。最后分析燃料电池的工作温度、工作压力以及制冷机内部不可逆性对混合系统生态学性能的影响。     

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.     

氢能知识系列讲座(6)利用氢能的高效设备(二)——高温燃料电池

本讲将介绍高温燃料电池,即工作温度在500～1000℃的燃料电池,主要指工作温度在900～1000℃的固体氧化物燃料电池(SOFC)和工作温度在650℃左右的熔融碳酸盐燃料电池(MCFC)。     

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。     

基于加权残值法的高温燃料电池温度分布特性的数值分析

加权残值法是一种可以直接从偏微分方程中求得近似解的数学方法。通过对熔融碳酸盐燃料电池(MCFC)内部传热传质过程的热力学性能分析,在质量守恒和能量守恒的基础上建立了MCFC温度动态分布的数学模型,并采用加权残值法对其进行求解分析。确定了满足模型边界条件的试函数,以三次正交多项式为基函数,利用加权残值法中的迦辽金法,结合Matlab工具得到MCFC温度的动态分布特性曲线。分析结果表明,燃料电池内部各点温度在空间分布上有很大差异;当供给燃料电池的燃料流量和氧化剂流量变化时,所引起的温度动态特性是复杂的。图3参5。     

绿色“火力”发电厂——面向21世纪的燃烧电池

熔融碳酸盐燃料电池（MCFC）发电是新世纪的高效、洁净的发电技术,特别是它可取代传统的燃煤、燃气火力发电,彻底解决火力发电污染大、效率低的弊端。本文首先分析了开发MCFC发电厂的必要性及资源条件;然后首次从电极、单电池、电堆、系统四个层次阐述了MCFC燃料电池的发电原理,并分析了四个层次中发生的主要热、电过程;给出了天然气MCFC发电厂、煤气化MCFC-燃气轮机-汽轮机联合发电厂的构成和主要过程。最后阐明了我国大力研究和开发MCFC发电厂的现实意义。     

熔融碳酸盐燃料电池阴极溶解与防护北大核心CSCD

熔融碳酸盐燃料电池(MCFC)是一种高效、可持续发电技术,其能源转换效率高、排放净化度高,是一种极具前途的发电技术。但是,由于其高工作温度和熔融碳酸盐电解质的特殊性质,MCFC的发展一直受到阻碍。其中,阴极溶解是一个严重的问题,会导致Ni短路等一系列问题,影响燃料电池的性能和寿命。本文综述了降低熔融碳酸盐燃料电池阴极溶解的策略,简述了近年来从替代材料、涂层改性和添加剂三个方面对阴极溶解的改善研究,探讨了替代NiO材料的方案不完全可行的问题,并提出了使用涂层技术来增强NiO阴极化学性能和降低阴极溶解度的可能性。涂层技术的优缺点也被详细列举,包括溶液浸渍电镀、溶胶-凝胶工艺和原子层沉积等一系列研究进展和性能。此外,本文还探讨了增加电解液碱度和向NiO中添加碱性氧化物来减少阴极溶解的方法,但也指出添加过多氧化物会降低电池性能的风险。综合分析表明,通过开发新型添加剂和涂层技术弥补合金作为阴极材料的性能缺陷,尝试制备新型复合材料等途径,有望获得高性能、低成本的阴极材料,从而实现MCFC的大规模商业化应用。     

熔融碳酸盐燃料电池的电气特性研究

为了研究熔融碳酸盐燃料电池的电气特性,分析了熔融碳酸盐燃料电池单元的电化学过程机理,建立了基于电化学反应的熔融碳酸盐燃料电池电气模型,推导了熔融碳酸盐燃料电池平均电流密度与燃气利用率的关系,给出了采用电化学方程的熔融碳酸盐燃料电池电气特性的模型结构和算法,并进行了仿真研究和试验.试验结果表明:该模型结构简单、准确度高,可获得千瓦级熔融碳酸盐燃料电池的电气特性曲线.     

磷酸燃料电池-两级热电系统性能分析及负载匹配

建立一个利用磷酸燃料电池(PAFC)余热驱动两级半导体温差热电发电器(TTEG)的复合发电系统模型,考虑了PAFC电化学反应中的过电势损失、回热损失、热漏以及TTEG中的主要不可逆损失,导出PAFC,TTEG和复合系统的输出功率和效率的一般表达式,得到PAFC和TTEG电流密度之间的关系。确定系统的优化工作区间,分析主要参数对复合系统性能的影响,给出负载电阻的最佳匹配条件,所得结果可为实际的PAFC-TTEG复合发电系统的设计和优化运行提供理论依据。     

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。     

Maximum equivalent efficiency and power output of a PEM fuel cell/refrigeration cycle hybrid system

With the help of the current models of proton exchange membrane (PEM) fuel cells and three-heat-source refrigeration cycles, the general model of a PEM fuel cell/refrigeration cycle hybrid system is originally established, so that the waste heat produced in the PEM fuel cell may be availably utilized. Based on the theory of electrochemistry and non-equilibrium thermodynamics, expressions for the efficiency and power output of the PEM fuel cell, the coefficient of performance and cooling rate of the refrigeration cycle, and the equivalent efficiency and power output of the hybrid system are derived. The curves of the equivalent efficiency and power output of the hybrid system varying with the electric current density and the equivalent power output versus efficiency curves are represented through numerical calculation. The general performance characteristics of the hybrid system are discussed. The optimal operation regions of some parameters in the hybrid system are determined. The advantages of the hybrid system are revealed.     

An available method exploiting the waste heat in a proton exchange membrane fuel cell system

Based on the models of a proton exchange membrane (PEM) fuel cell working at steady state and a semiconductor thermoelectric generator, a hybrid system consisting of a PEM fuel cell, a semiconductor thermoelectric generator, and a regenerator is originally put forward. Expressions for the efficiencies and power outputs of the fuel cell, thermoelectric generator, and hybrid system are derived. The relation between the operating electric currents in the fuel cell and thermoelectric generator is obtained. The maximum power output of the hybrid system is numerically given. The optimally operating electric currents in the fuel cell and thermoelectric generator are calculated, and consequently, the optimal region of the hybrid system is determined. The results obtained here will provide some guidance for further understanding the performance and operation of practical PEM fuel cell-thermoelectric generator hybrid systems.     

Performance analysis of a pressurized molten carbonate fuel cell/micro-gas turbine hybrid system

This paper presents the work on the design and part-load operations of a hybrid power system composed of a pressurized molten carbonate fuel cell (MCFC) and a micro-gas turbine (MGT). The gas turbine is an existing one and the MCFC is assumed to be newly designed for the hybrid system. Firstly, the MCFC power and total system power are determined based on the existing micro-gas turbine according to the appropriate MCFC operating temperature. The characteristics of hybrid system on design point are shown. And then different control methods are applied to the hybrid system for the part-load operation. The effect of different control methods is analyzed and compared in order to find the optimal control strategy for the system. The results show that the performance of hybrid system during part-load operation varies significantly with different control methods. The system has the best efficiency when using variable rotational speed control for the part-load operation. At this time both the turbine inlet temperature and cell operating temperature are close to the design value, but the compressor would cross the surge line when the shaft speed is less than 70% of the design shaft speed. For the gas turbine it is difficult to obtain the original power due to the higher pressure loss between compressor and turbine.     

Molten-salt fuel cells—Technical and economic challenges

This paper presents a personal view of the status and research needs of the MCFC and other molten-salt fuel cells. After an overview of current MCFC performance, compared with performance and cost of other fuel cells, improvements in power density and lifetime as well as cost reduction are identified as key priorities to accelerate the commercialization of the MCFC. In spite of its unfavorable public image (compared to, in particular, PEMFC and planar SOFC) MCFC technology has progressed steadily and cost reduction has been significant. Large-scale commercialization, especially in the distributed generation and cogeneration market, remains a possibility but its chances are highly dependent on a forceful and consistent energy policy, for example taking into account the externalities associated with various modes of electric power production from fossil fuels. In spite of steady improvements in performance, important defects in fundamental knowledge remain about wetting properties, oxygen reduction kinetics, corrosion paths and control mechanisms. These must be addressed to stimulate further simplification of design and find solutions to lifetime issues. Recently, alternative concepts of molten-salt fuel cells have been capturing attention. The direct carbon fuel cell (DCFC), reviving an old concept, has caught the attention of energy system analysts and some important advances have been made in this technology. Direct CO and CH₄ oxidation have also been a focus of study. Finally, the potential of nanotechnology for high-temperature fuel cells should not be a priori excluded.     

Molten carbonate fuel cell (MCFC)-based hybrid propulsion systems for a liquefied hydrogen tanker

This study proposes a molten carbonate fuel cell (MCFC)-based hybrid propulsion system for a liquefied hydrogen tanker. This system consists of a molten carbonate fuel cell and a bottoming cycle. Gas turbine and steam turbine systems are considered for recovering heat from fuel cell exhaust gases. The MCFC generates a considerable propulsion power, and the turbomachinery generates the remainder of the power. The hybrid systems are evaluated regarding system efficiency, economic feasibility, and exhaust emissions. The MCFC with a gas turbine has higher system efficiency than that with a steam turbine. The air compressor consumes substantial power and should be mechanically connected to the gas turbine. Although fuel cell-based systems are less economical than other propulsion systems, they may satisfy the environmental regulations. When the ship is at berth, the MCFC systems can be utilized as distributed generation that is connected to the onshore-power grid.     

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     

Integration of molten carbonate fuel cell and looped multi-stage thermoacoustically-driven cryocooler for electricity and cooling cogeneration

Thermal management is essential for high-temperature molten carbonate fuel cell (MCFC) because the accumulated waste heat may degrade the durability. In this paper, looped multi-stage thermoacoustically-driven cryocooler (LMTC) is proposed to reuse the waste heat from MCFC for cooling production, which not only can tackle with the thermal management issue but also can provide additional usages. Accounting various irreversible dissipation, the models of MCFC, LMTC and MCFC-LMTC hybrid system are analytically formulated. Performance features of MCFC-LMTC hybrid system are revealed and the advantages are expounded via calculation examples. Calculations indicate that the maximum power density and corresponding efficiency of the hybrid system are 1688.9 W m^?2 and 39.7%, which are 11.4% and 1.3% bigger than that of the sole MCFC system, respectively. By comparing with other available systems, the superiority of using LMTC to recover MCFC waste heat for refrigeration is clearly demonstrated. Considerable parametric studies show that the heat-transfer coefficient of hot heat exchange for LMTC is not suggested to be greater than 2.5 × 10^?3 W m^?2 K^?1. In addition, an increase in the working temperature, working pressure of MCFC, reactant concentration or engine stage number of LMTC positively benefits the hybrid system performance, while an increase in the thermodynamic loss coefficient worsens the hybrid system performance. The obtained results may offer new insights into improving the performance of MCFCs through thermal management approaches.     

A theoretical study of molten carbonate fuel cell combined with a solar power plant and Cu–Cl thermochemical cycle based on techno-economic analysis

A novel power and hydrogen coproduction system is designed and analyzed from energetic and economic point of view. Power is simultaneously produced from parabolic trough collector power plant and molten carbonate fuel cell whereas hydrogen is generated in a three-steps Cu–Cl thermochemical cycle. The key component of the system is the molten carbonate fuel cell that provides heat to others (Cu–Cl thermochemical cycle and steam accumulator). A mathematic model is developed for energetic and economic analyses. A parametric study is performed to assess the impact of some parameters on the system performance. From calculations, it is deduced that electric energy from fuel cell, solar plant and output hydrogen mass are respectively 578 GWh, 25 GWh and 306 tons. The overall energy efficiency of the proposed plants is 46.80 % and its LCOE is 7.64 c€/kWh. The use of MCFC waste heat allows increasing the solar power plant efficiency by 2.15 % and reducing the annual hydrogen consumption by 3 %. Parametric analysis shows that the amount of heat recovery impacts the energy efficiency of fuel cell and Cu–Cl cycle. Also, current density is a key parameter that influences the system efficiency.     

Simulation and modeling of copper-chlorine cycle,molten carbonate fuel cell alongside a heat recovery system named regenerative steam cycle and electric heater with the incorporation of PID controller in MATLAB/SIMULINK

MCFC (molten carbonate fuel cell) is a relatively new kind of fuel cell that may be utilized in both local and large-scale energy distribution and generating systems. MCFCs are largely regarded as a viable source of renewable energy. Making an MCFC is a time-consuming and costly process. Mathematical modeling and efficiency simulations are essential to appropriately maximize its performance. Regenerative cycle, copper-chlorine cycle, and electric heater with PID controller is also studied to integrate them with MCFC to increase the efficiency of the overall system. Copper–Chlorine cycle is integrated to provide a stable stream of hydrogen and oxygen for the fuel cell. The Molten Carbonate fuel cell of stack 100 generates 1.203 MW of power at Voltage of 1.2 V each. Waste Heat recovery system is installed named regenerative Steam cycle which produces 2.94 MW of power. The total efficiency of system is 57% and the total extracted power is 4.143 MW. MATLAB/Simulink R2020a is used for modeling of multigeneration system with use of Engineering Equation Solver.     

千瓦级空间堆热离子—碱金属混合式热电转换系统设计及性能

针对空间核电转换系统静态热电转换发电效率低的问题，设计开发了一种新型的热离子-碱金属混合发电系统，即利用热离子转换系统的余热作为碱金属转换器的热源，利用余热进行二次发电以提高转换系统效率，通过建立热离子-碱金属混合发电系统数理模型，研究了热离子热电转换系统接收极功函数和系统电流密度对混合发电系统功率效率的影响，得到了两个参数的最优区间，计算结果表明热离子-碱金属混合发电系统相比于热离子热电转换系统效率约6％~10％，为静态热电转换系统的效率优化提供了理论依据。