Degradation kinetics of LSM–YSZ cathode materials for SOFC

Solid oxide fuel cells are perspective electrochemical devices for hydrogen energy applications and require long time performance. The paper studies the influence of the processes of particles coarsening and cation interdiffusion on the degradation kinetics of the LSM–YSZ cathode material catalytic activity as related to the interaction processes with oxygen from the gas phase. The exchange kinetics with the gas phase oxygen was studied by the oxygen isotope exchange method with the gas phase equilibration at the temperature of 850 °С and Po₂ = 10^?2 atm. The samples were exposed for 1000 h. The coefficient of gas phase and surface oxygen exchange was found to decrease at the exposure. The paper discusses the physical reasons, which lead to the oxygen surface exchange coefficient decrease in LSM–YSZ electrodes and degradation of the polarization conductivity measured by electrochemical impedance spectroscopy.     

SOFC尾气催化燃烧特性

为验证并研究商业三元催化剂应用于SOFC尾气处理的可行性和方法,探究并对比了直接燃烧及商业三元催化剂在一段、二段催化燃烧模式下尾气的催化转化特性.一段催化燃烧时,进口温度的增加及当量比的降低可以提升H2和CO的转化率,低温脱除尾气水蒸气降低了H2和CO的转化率.基于优化工况,一段催化燃烧在168 h内出口CO2含量稳定...     

Performance and stability of SOFC anode fabricated from NiO–YSZ composite particles

Ni–YSZ cermet anodes for solid oxide fuel cells (SOFCs) were fabricated at various sintering temperatures from NiO–YSZ composite particles made by spray pyrolysis (SP) technique. NiO particles covered with fine YSZ (Y₂O₃ stabilized ZrO₂) particles were used as the composite particles, and the initial ratio of Ni and YSZ was set at 75:25 (mol%). As a result, the cermet anode sintered at 1350 °C showed the morphology in which fine YSZ grains were uniformly dispersed on the surface of Ni grain network. Electrical performance such as electrochemical activity and internal resistance of a Ni–YSZ cermet anode changed with sintering temperature. The anode fabricated at 1350 °C showed the highest electrical performance. Especially, a single cell voltage with the Ni–YSZ cermet anode kept very stable for 8000 h at 1000 °C in the SOFC operation condition of H₂—3% H₂O and air. The cermet anode after a long-term test had its initial morphology. It indicates that the Ni–YSZ cermet anode fabricated from NiO–YSZ composite particles is a very promising material for its practical use as SOFCs.     

Evaluation of Laves-phase forming Fe–Cr alloy for SOFC interconnects in reducing atmosphere

A Laves-phase forming Fe–Cr alloy was evaluated as interconnects for solid oxide fuel cells (SOFCs) in reducing atmosphere (in H₂-H₂O). The oxide scale growth was compared between Laves-phase forming alloy and typical stainless steel (SUS430). The oxide scale growth rates were decreased in the Laves-phase forming alloy, and the area-specific resistance (ASR) of oxidized Laves-phase forming alloy showed the lower values than that of SUS430. The temperature dependence of 1/ASR for the oxidized alloy was different between Laves-phase forming alloy and SUS430. The oxygen diffusivity in the oxide scale was also evaluated by the stable isotope oxygen (¹⁸O₂) diffusion in the scale. The chemical diffusion coefficients of isotope oxygen in the oxide scale showed the smaller value for the Laves-phase forming alloy (D = 7.0 × 10⁻¹³ cm² s⁻¹) than that for SUS430 (D = 4.6 × 10⁻¹² cm² s⁻¹) at 1073 K. A relatively high diffusivity of oxygen was estimated in the Mn–Cr spinel oxide on the top surface of oxide scales. Inward diffusion of oxygen and outward diffusion of cation in the oxide scale were discussed to consider the oxide scale growth mechanism.     

ISAT在SOFC氢氧反应中的应用

现代先进能源系统普遍具有复杂性和多尺度特性,其模拟研究存在的最大问题是计算代价过高.为了提高计算效率,将非结构化自适应建表法(in situ adaptive tabulation,ISAT)与动力学蒙特卡洛法(kineticsMonte Carlo,KMC)相结合,在误差允许的范围内,通过采用近似插值计算代替部分耗时的微观模拟过程,达到减少计算时间的目的.以固体氧化物燃料电池(solid oxide fuel cell,SOFC)为例,对其在不同参数条件下氢氧反应过程进行仿真研究.仿真结果表明,在满足精度要求的前提下,所建立起的混合方法相比于单独使用kMC能够有效的缩短计算时间,提高计算效率.     

天然气水蒸气重整与SOFC耦合应用

固体氧化物燃料电池（SOFC）系统具有高能源效率和使用可再生燃料的可能性,将在未来的可持续能源系统中发挥重要作用。过去几年燃料电池的发展很快,但在成本、稳定性和市场份额方面,该技术仍处于早期发展阶段。在以天然气为燃料的SOFC系统中,燃料的重整过程和燃料利用水平都可能影响系统运行的稳定性、热量和能量平衡,从而影响系统的使用寿命、输出功率和效率。因此,对燃料重整过程的设计与控制对有效的SOFC电池运行具有重要意义。对天然气在SOFC系统中的重整器配置方式（包括外重整和内重整）、重整参数和重整燃料利用方式进行了详细的综述分析,并对未来天然气SOFC系统的发展进行了展望。     

SOFC在天然气分布式应用中的经济性分析

固体氧化物燃料电池属于第三代燃料电池,是一种在中高温下直接将储存在燃料和氧化剂中的化学能高效、环境友好地转化成电能的全固态化学发电装置。固体氧化物燃料电池具有燃料适应性广、能量转换效率高、全固态、模块化组装、零污染等优点,可直接使用氢气、一氧化碳、天然气、液化气、煤气及生物质气等多种碳氢燃料。对不同应用场景下以天然气为燃料的固体氧化物燃料电池分布式应用进行经济性分析。     

SOFC／GT混合系统的计算机仿真

固体氧化物燃料电池(SOFC)/燃气轮机(GT)混合系统以其高效、低污染排放的优点受到各国尤其是西方发达国家的重视,被认为是解决21世纪能源与环境问题的关键技术之一.计算机仿真方法是目前研究SOFC/GT混合系统的主要方法之一.本文利用Aspen Custom Modeler 仿真平台对一回热器空气再热式SOFC/GT系统进行了仿真分析,给出了设计工况下混合循环各部件节点的状态参数值,分别就压比、燃料电池电流密度和燃料利用率对系统发电效率的影响进行了仿真分析.仿真结果表明,系统总发电效率随压比的关系曲线呈抛物线型,随着压比的增大,系统的发电效率先增大后减小.系统总发电效率与电流密度成反比关系,而与燃料利用率成正比;燃料电池的发电效率与电流密度和燃料利用率均成反比.     

Geometric optimization of an ejector for a 4 kW SOFC system with anode off-gas recycle

One of the important energy saving tools used in solid oxide fuel cell (SOFC) system is the anode off-gas recycling (AGR) via an ejector which allows the recirculation of the unused fuels in the anode exhaust gas including hot steam which is essential for the elimination of the carbon deposition and the initiation of the reactions in the reformer. In an ejector system developed for the SOFCs, the steam to carbon ratio (STCR) and entrainment ratio are the crucial parameters for the determination of the ejector performance. These parameters can be engineered by modifying the geometric dimensions and operation conditions. This study focuses on the determination of the maximum STCR value and entrainment ratio via numerical geometric analyses for a micro combined heat and power (μ-CHP) system based on 4 kW SOFC, utilizing methane. A detailed numerical procedure for designing an ejector is provided and the ejector performance is investigated for different critical dimensions (throat diameter, nozzle exit angle and nozzle position etc.). The results show that the nozzle position and the nozzle exit angle significantly affect STCR and the entrainment ratio. When the nozzle position increases and nozzle exit angle decreases, the entrainment ratio and STCR is found to increase. The entrainment ratio and STCR are determined as around 7.3 and 2.7, respectively for a specific design created in the study.     

The preparation and properties of Mn–Co–O spinel coating for SOFC metallic interconnect

To meet the performance requirements of solid oxide fuel cell (SOFC) metallic interconnect, the Mn–Co–O spinel coating is prepared on the surface of AISI430 by pack cementation method to reduce the growth kinetics of oxides and inhibit the outward diffusion of Cr. The microstructural characterization shows that a dense, uniform, defect-free spinel coating is successfully fabricated on the surface of AISI430. Under the simulated SOFC cathode environment, the weight gain of coated steel (0.608 mg cm⁻²) after oxidation at 800 °C for 800 h is significantly lower than that of uncoated (1.586 mg cm⁻²). In addition, the area specific resistance (ASR) of the coated steel oxidized for 500 h is 17.69 mΩ cm², much smaller than that of the bare steel, indicating that the oxidation resistance and electrical conductivity of AISI430 are significantly improved by Mn–Co–O spinel coating. Cross-sectional observations of the Mn–Co–O spinel coating are conducted to assess the compatibility of substrate with the adjacent coating and its effectiveness in reducing the growth of the Cr₂O₃ layer.     

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     

Enhancement of energy generation efficiency in industrial facilities by SOFC – SOEC systems with additional hydrogen production

Industry is one of the highest energy consumption sector: some facilities like steelworks, foundries, or paper mills are highly energy-intensive activities. Many countries have already implemented subsidies on energy efficiency in generation and utilisation, with the aim of decreasing overall consumption and energy intensity of gross domestic product. Meanwhile, researchers have increased interest into alternative energy systems to decrease pollution and use of fossil fuels. Hydrogen, in particular, is proposed as a clean alternative energy vector, as it can be used as energy storage mean or to replace fossil fuels, e.g. for transport.This work analyses the re-vamping of the energy generation system of a paper mill by means of reversible solid oxide cells (RSOCs). The aim is not only to increase efficiency on energy generation, but also to create a polygeneration system where hydrogen is produced. Application on a real industrial facility, based in Italy with a production capacity of 60000 t/y of paper, is analysed. First, the current energy system is studied. Then, a novel system based on RSOC is proposed. Each component of the systems (both existing and novel) is defined using operational data, technical datasheet, or models defined with thermodynamic tools. Then, the interaction between them is studied. Primary energy analysis on the novel system is performed, and saving with respect to the current configuration is evaluated. Even if the complexity of the system increases, results show that saving occurs between 2 and 6%. Hydrogen generation is assessed, comparing the RSOC integrated system with proton exchange membrane (PEM) electrolysis, in terms of both primary energy and economics. Results exhibit significant primary energy and good economic performance on hydrogen production with the novel system proposed (hydrogen cost decreases from 10 €/kg to at least 8 €/kg).     

以SOFC为发电设备的热泵型BCCHP系统

针对目前建筑冷热电联供系统发电设备效率低和余热利用方式不当造成能耗偏高的现状,提出了一种以固体氧化物燃料电池为发电设备的热泵型BCCHP系统,介绍了该系统的运行原理及结构配置特点,通过对系统组件的建模、模拟与集成,以一个80kW电力需求的用户为例进行实例研究,实例表明:在设计工况下,热泵型SOFC-BCCHP系统冬季的发电效率、供热效率分别为46.3%、51.9%,夏季系统的发电效率、供冷效率分别为46.3%、32.5%,系统的综合效率均较传统系统有明显提高,是高效的能源转换方式与高效的能源利用方式的综合,具有一定的推广价值.     

基于甲烷催化部分氧化的SOFC性能研究

基于固体氧化物燃料电池的热电联供系统可以实现能源的梯级利用,实现较高的效率,降低污染排放,具有很好的发展前景.针对该系统中传统重整器存在的高能耗等问题,对新型重整方式催化部分氧化进行了研究.本文首先研究了催化剂为0.5%Rh/Al2O3,以甲烷为燃料时CPOX的性能变化规律.通过调节控制温度、体积空速和入口气C/O比,研究了不同工况下CH4转化率、H2选择性、CO选择性和甲烷重整效率的变化规律,对工况进行优化.在优化工况下,即温度800℃、体积空速200 min-1、C/O摩尔比为1.0时,实现了催化部分氧化与微管式固体氧化燃料电池四管电堆的直接耦合,并对电池性能进行测试,结果表明,最大功率可达到纯氢燃料的87.8%.     

SOFC热电联供系统的设计方法研究

介绍了固体氧化物燃料电池建筑热电联供系统的各种结构流程,提出SOFC系统的设计路线,通过对SOFC系统的建模和模拟,开发出一种用于BCHP中燃料电池系统的设计方法,并利用该方法进行实例设计,结果表明:该方法可以针对用户的能源需求计算所需的燃料电池电堆的容量及系统辅助设备的容量,为电堆规模的确定、系统配套辅助设备的选型提供重要的参考依据,为SOFC在BCHP中的应用提供一个有力的系统设计工具.     

Post-mortem evaluation of oxidized atmospheric plasma sprayed Mn–Co–Fe oxide spinel coatings on SOFC interconnectors

Interconnects employed in solid oxide fuel cells require electrically conductive protective coatings such as those based on manganese cobalt oxide spinels in order to prevent evaporation of volatile Cr(VI)-compounds and to minimize high temperature corrosion. MnCo_2−xFe_xO₄ based (where x = 0.1 and 0.3) oxide spinel protective coatings were manufactured by the atmospheric plasma spraying process on Crofer 22 APU substrates. The coated substrates were oxidized at 700 °C in air for 1000 h and post-mortem analyses were conducted to study the performance of the thermal sprayed coatings. During the high temperature oxidation, a four-point on-line measurement technique was used for area specific resistance studies. The MnCo_1.7Fe_0.3O₄ coating was tested together with the La_0.85Sr_0.15Mn_1.1O₃-spacer.     

高温燃料电池—固体氧化物燃料电池（SOFC）

燃料电池是一种直接把燃料的化学能转变为电和热的电化装置,无需经过燃烧这一中间环节。与其它发电装置相比,转化效率达到60％左右,部分负荷时的效率也高;具有积木式结构,场地限制性小以及污染小等优点,是一种清洁发电方式;与风能、太阳能等发电方式相比,又具有较高的能量密度特点。其运行温度超过600℃,产生高品位的蒸汽,可用于热电并供或底部循环。但也存在着材料、耐腐蚀、寿命周期、制造等技术难题。日前高温燃料电池主要有熔融碳酸盐燃料电池和固体氧化物燃料电池。本文将主要叙述固体氧化物燃料电池(Solid Oxide Fuel Cell——SOFC)的发展现状,运行原理及其应用。