平板式固体氧化物燃料电池多物理场耦合建模

固体氧化物燃料电池(Solid oxide fuel cell,SOFC)在高温下工作,影响电池性能和结构完整性的因素众多,如何能够综合考虑这些因素并准确地预测和优化电池结构与工作性能是亟待解决的问题。使用COMSOL软件建立了单个平板式固体氧化物燃料电池多场耦合有限元三维模型,考虑电化学反应、物质浓度、流体流动、传热和固体力学多物理因素共同作用下,探明了电池在工作阶段的气体摩尔分数、电流密度、温度和热应力的分布规律。结果表明,氢气和氧气的摩尔分数随着气体流动的方向逐渐降低;在电池空气入口处,电解质电流密度较大;电池温度分布不均匀并产生了较大的热应力。本文建立的SOFC多场耦合模型可为后续SOFC的研究提供分析方法和理论支持。     

三维顺排阳极自呼吸微流体燃料电池性能特性

自呼吸微流体燃料电池是很有前景的新型微型电源,目前其性能的主要限制因素是阳极燃料传质。本文构建了具有三维顺排阳极的自呼吸微流体燃料电池,利用圆柱形阳极在流道中容积式的分布增大反应面积,强化燃料传输。本文研究了燃料浓度和反应物流量对电池性能的影响,并对流道中的两相流动进行了可视化观察。实验结果表明:随燃料浓度或反应物流量的增加,电池性能先升高后降低;产生的CO_2气泡能够被限制在阳极电极和隔离棒中,减小了其对阴极侧电解液流动的扰动;气泡会在隔离棒之间聚并形成气膜,气膜周期性形成和排出的动态行为对电池的放电性能具有较大影响。     

固体氧化物直接碳燃料电池的模型计算

直接碳燃料电池(DCFC)是直接以碳或煤为燃料的燃料电池.本文以一种以固体氧化物为电解质的固定床直接碳燃料电池为对象,基于文献中的实验数据,建立了物理模型和数学方程,求解出电池在三个特定温度下的V-I曲线以及能量转换效率,并与文献中的实验结果进行对照,验证了对固定床直接碳燃料电池的反应过程的假设,分析了电池性能的影响因素,为直接碳燃料电池的应用打下了理论基础.     

具有可渗透阳极的自呼吸微流体燃料电池性能特性

微流体燃料电池去除了质子交换膜,避免了膜退化、水管理等问题,是微型燃料电池领域新的研究热点。本文构建了具有可渗透阳极和空气自呼吸阴极的微流体燃料电池,采用甲酸溶液作为燃料对其性能特性进行了实验研究。结果表明:具有可渗透阳极的自呼吸微流体燃料电池性能随燃料浓度或流量的增加先升高后下降,随电解液浓度的增加而升高;阳极侧反应产生的CO₂气泡对自呼吸微流体燃料电池的性能和燃料利用率的影响较大,适当提高燃料流量有利于气泡的排除。     

PEMFCs的膜及阴极催化层数值模拟

本文提出了一个质子交换膜燃料电池的膜和阴极催化层的一维非稳态数学模型,模型考虑了电化学反应及反应中的传质过程。本文结合算例分析了燃料电池膜及阴极催化层的性能,结果能验证燃料电池内阻理论。论文结果表明:(1)随着输出电流密度的增大,氧浓度分布不均匀性增大; (2)阴极催化层厚度减小,可提高电池输出电压; (3)电池进口处氧气摩尔浓度增大,可增加电池的输出电压。     

质子交换膜燃料电池动力系统变工况模拟

质子交换膜燃料电池堆是燃料电池汽车的关键单元之一，电池堆负荷变化及跟踪的动力学特性是衡量其性能优劣的重要指标．因此基于汽车动力系统及其单元的动态特性研究和控制回路设计，有必要开展电池堆的稳态变工况模拟，作为今后深入研究的基础．     

不同流场下进气对质子交换膜燃料电池性能的影响

流场的结构对于质子交换膜燃料电池(PEMFC)的水管理和气体的传递具有十分重要的影响,相关研究一直是燃料电池的研究热点与重点。本文以纯氧气和空气作为阴极氧化剂,通过电池的性能测试、极化曲线和电化学阻抗分析等原位实验,分析了气体的流动与传输、不同流场下的电流密度、入口反应气体浓度等条件对电池性能的影响。实验结果表明,提高氧气浓度可以获得更好的质子交换膜燃料电池性能和最小化活化损失,纯氧气、波状流场的使用效果随进气量的变化而有明显的变化。     

质子交换膜燃料电池电流分布的动态响应

动态特性是理解质子交换膜燃料电池性能的重要参数之一.运用燃料电池测试系统、恒电流/恒电压多通道测试仪和燃料电池电流密度分布测试装置,试验测量了质子交换膜燃料电池在不同加湿温度、电池温度和压力下的电流分布动态响应和动态特性.研究发现:不同区域的局部电流达到新的平衡所需的时间不同;加湿温度变化时,不同区域的局部电流的变化趋...     

生物质气为燃料的燃料电池理论电动势计算

在以生物质气体为燃料的固体氧化物燃料电池体系中,通过热力学平衡分析编程计算出700-1200 K时气体中各物种例如H2、CO、CO2和CH4的平衡组成,从而得到以氧化钇稳定氧化锆(YSZ)为电解质的电池理论电动势．碳沉积对电动势有显著影响．通过计算可以推测比较适宜的操作温度和增湿条件．还计算了以掺杂氧化铈为电解质的电池电动势,相比氢气为燃料时,使用生物质气体导致的电动势的下降比使用YSZ为电解质的电池要小的多．     

涡发生器对质子交换膜燃料电池性能影响

通过数值模拟,研究了涡发生器的形状、间距、攻角和组数对于质子交换膜燃料电池性能的影响。结果表明,在燃料电池阴极流道中安装5组、12 mm间距、攻角为45?的矩形小翼涡流发生器,对于燃料电池性能的提升最为明显,电流密度最高提升了33.3%;电流密度随着涡发生器间距、攻角和组数的增加而增大;涡发生器改善了燃料电池内部的温度、水含量和氧含量分布,有利于积水的排出,且可以明显的观察到涡量大小与电流密度呈正相关。     

On the role of fusion neutron source with thorium blanket in forming the nuclide composition of the nuclear fuel cycle of the Russian Federation

The possible role of available thorium resources of the Russian Federation in utilization of thorium in the closed (U–Pu)-fuel cycle of nuclear power is considered. The efficiency of application of fusion neutron sources with thorium blanket for economical use of available thorium resources is demonstrated. The objective of this study is the search for a solution of such major tasks of nuclear power as reduction of the amount of front-end operations in the nuclear fuel cycle and enhancement of its protection against uncontrolled proliferation of fissile materials with the smallest possible alterations in the fuel cycle. The earlier results are analyzed, new information on the amount of thorium resources of the Russian Federation is used, and additional estimates are made. The following basic results obtained on the basis of the assumption of involving fusion reactors with Th-blanket in future nuclear power for generation of the light uranium fraction ^232+233+234U and ²³¹Pa are formulated. (1) The fuel cycle would shift from fissile ²³⁵U to ²³³U, which is more attractive for thermal power reactors. (2) The light uranium fraction is the most “protected” in the uranium fuel component, and being mixed with regenerated uranium, it would become reduced-enrichment uranium fuel, which would relieve the problem of nonproliferation of the fissile material. (3) The addition of ²³¹Pa into the fuel would stabilize its neutron-multiplying properties, thus making it possible to implement a long fuel residence time and, as a consequence, increase the export potential of the whole nuclear power technology. (4) The available thorium resource in the vicinity of Krasnoufimsk is sufficient for operation of the large-scale nuclear power industry of the Russian Federation with an electric power of 70 GW for more than one quarter of a century. The general conclusion is that involvement of a small number of fusion reactors with Th-blanket in the future nuclear power industry of the Russian Federation would to a large extent solve its problems and increase its export potential.     

Accelerator-driven sub-critical reactor system (ADS) for nuclear energy generation

In this talk we present an overview of accelerator-driven sub-critical reactor systems (ADS), and bring out their attractive features for the elimination of troublesome long-lived components of the spent fuel, as well as for nuclear energy generation utilizing thorium as fuel. In India, there is an interest in the programmes of development of high-energy and high-current accelerators due to the potential of ADS in utilizing the vast resources of thorium in the country for nuclear power generation. The accelerator related activities planned in this direction will be outlined.     

冷热电联产系统的评价准则

本文通过对以燃气轮机回热循环为动力系统的冷热电联产系统进行热力学分析,对几种常用的评价准则进行了比较。通过分析,认为能量利用系数将冷、热、电等各股能量等价看待,(火用)效率过分看重能量的作功能力,折合发电效率过分关注冷、热能的输出,均不适于冷热电联产系统的评价;节能率反映的是输入能量的使用情况,经济(火用)效率在某种程度上是经济性的表现,比较适于冷热电联产系统的评价。研究中发现,燃气轮机温比有利于系统性能的提高,但针对不同的目标有不同的最佳压比;在节能率的使用中需要明确参照系统的性能。     

In situ observation of water distribution and behaviour in a polymer electrolyte fuel cell by synchrotron X‐ray imaging

In situ visualization of the distribution and behaviour of water in a polymer electrolyte fuel cell during power generation has been demonstrated using a synchrotron X‐ray imaging technique. Images were recorded using a CCD detector combined with a scintillator (Gd₂O₂S:Tb) and relay lens system, which were placed at 2.0 m or 2.5 m from the fuel cell. The images were measured continuously before and during power generation, and data on cell performance was recorded. The change of water distribution during power generation was obtained from X‐ray images normalized with the initial state of the fuel cell. Compared with other techniques for visualizing the water in fuel cells, this technique enables the water distribution and behaviour in the fuel cell to be visualized during power generation with high spatial resolution. In particular, the effects of the specifications of the gas diffusion layer on the cathode side of the fuel cell on the distribution of water were efficiently identified. This is a very powerful technique for investigating the mechanism of water flow within the fuel cell and the relationship between water behaviour and cell performance.     

PCM软件包燃料组件弯曲模型的开发及验证北大核心CSCD

燃料组件在反应堆内受压紧力等作用会发生弯曲,该弯曲会显著改变反应堆局部位置的中子慢化。基于中广核核设计软件包PCM中的组件中子截面计算软件PINE和堆芯核设计软件COCO,开发了专门的燃料组件弯曲模型,以分析燃料组件弯曲对堆芯局部功率分布的影响,并和蒙特卡罗软件JMCT做了对比验证计算。计算结果表明,PCM软件包燃料组件弯曲模型的计算结果与JMCT吻合良好,该软件包可以用于燃料组件弯曲的分析计算。燃料组件的弯曲对于堆芯的局部功率分布有显著的影响,需要在设计中予以特别关注。     

Composites of Proton-Conducting Polymer Electrolyte Membrane in Direct Methanol Fuel Cells

Fuel cells are a replacement for the conventional energy resources. As early as 1839, William Grove discovered the basic operating principle of fuel cells by reversing water electrolysis to generate electricity from hydrogen and oxygen. A Direct Methanol Fuel Cell (DMFC) operates on liquid fuel, which is one of the exciting varieties of fuel cells. There are many problems with DMFCs such as the high cost of electrolyte membranes, high platinum loading, CO poisoning, fuel cross-over, and so on. In this review, research regarding the solution of these problems will be cited and discussed. The electrical performance (in respect to power density) of the composites for the Nafion® and other perfluorinated membranes in DMFC are evaluated. The effect of these modifications on various aspects, such as mobility of protons through the membrane, permeation of hydronium ions, and cross-over of methanol through the membrane leading to the negative potential, have previously been discussed. Therefore, the main focus of this review is on the effect of composites of Nafion® and non-fluorinated membranes on the DMFC performance.     

压水堆核电站燃料组件弯曲对堆芯中子学的影响分析计算

在压水堆核电站中,由于燃料组件装配的压紧力、冷却剂流动、辐射蠕变、燃耗等因素会导致燃料组件的弯曲,燃料组件的弯曲对组件间的水隙分布产生影响,从而影响中子的慢化行为及堆芯的传热性能,进而对反应堆堆芯的运行参数造成影响。本文分析了组件弯曲的成因及机理、影响及后果（包括对堆芯功率分布、径向功率倾斜、焓升因子、热点因子等参数的影响）,并使用蒙特卡罗软件JMCT,对组件弯曲的确定论计算程序的正确性进行了验证。最后通过确定论的计算程序模块,对CPR1000核电站的组件弯曲情况进行了模拟分析,计算结果表明:在某一燃耗下,随着水隙增加或减小,燃料组件功率会随之增加或减小,使堆芯的功率分布发生倾斜,影响核电站的安全运行。     

Advantages of Production of New Fissionable Nuclides for the Nuclear Power Industry in Hybrid Fusion-Fission Reactors

A concept of a large-scale nuclear power engineering system equipped with fusion and fission reactors is presented. The reactors have a joint fuel cycle, which imposes the lowest risk of the radiation impact on the environment. The formation of such a system is considered within the framework of the evolution of the current nuclear power industry with the dominance of thermal reactors, gradual transition to the thorium fuel cycle, and integration into the system of the hybrid fusion-fission reactors for breeding nuclear fuel for fission reactors. Such evolution of the nuclear power engineering system will allow preservation of the existing structure with the dominance of thermal reactors, enable the reprocessing of the spent nuclear fuel (SNF) with low burnup, and prevent the dangerous accumulation of minor actinides. The proposed structure of the nuclear power engineering system minimizes the risk of radioactive contamination of the environment and the SNF reprocessing facilities, decreasing it by more than one order of magnitude in comparison with the proposed scheme of closing the uranium–plutonium fuel cycle based on the reprocessing of SNF with high burnup from fast reactors.     

The path to fusion power

Fusion, which powers the sun and stars, is potentially an environmentally responsible and intrinsically safe source of essentially limitless energy. The Joint European Torus (JET) has produced 16 MW of fusion power, and construction of a power station sized device called ITER (International Tokamak Experimental Reactor), which should produce at least 500 MW, is about to begin. Further work on fusion technologies is also needed, including construction of the proposed International Fusion Materials Irradiation Facility (IFMIF) which will test materials that will have to stand up to years of intense neutron bombardment in a fusion power station. Given i) its potential attractions (which include essentially limitless fuel, and the absence of green-house gas and of long-lived radio-active by-products), and that ii) it looks as if the economics of fusion power will be acceptable, the time has come to develop fusion as rapidly as reasonably possible. The status and potential advantages of fusion are being described, together with the outstanding challenges, the remaining steps and a timetable for developing fusion power.     

核电站乏燃料对生物圈的影响及ADS 对策

介绍了核电发展状况和核电产生的乏燃料中的锕系及长寿命裂变产物核素， 在毒性方面评述了这些核素对生物圈的影响， 最后提出用加速器驱动的次临界系统嬗变核废物的对策， 以减轻或消除核废物对生物圈的影响。 The current status of nuclear power development and the actinides and some Long Lived Fission Products (LLFPs) in nuclear power spent fuel have been introduced. The radiation effect of spent fuel on biological circle in the viewpoint of Biological Hazard Potential (BHP) and Annual Limit of Intake were evaluated. The Accelerator Driven Sub critical System （ADS） as a strategy to transmute Minor Actinides (MAs) and LLFPs was recommended in order to reduce or eliminate the radiation effect of spent fuel on biological circle.