质子交换膜电解池二维两相流综合模拟研究

建立一个二维、非等温质子交换膜电解池两相流稳态模型,研究不同电压下电解池膜电极组件（MEA）中温度、液态水饱和度、膜态水分布以及温度、液态水饱和度和膜厚对质子交换膜电解池性能的影响,并通过实验验证模型的可靠性。实验结果表明：即使忽略接触电阻,膜润湿性较好,高电压（2.0 V）下欧姆损失占比仍可达到34.7%;随着电压的增大,极化损失的主导部分由活化损失变为欧姆损失,且传质损失占总极化损失的比例最小;当电压较小时,膜水含量是质子交换膜（PEM）电导率的主要影响因素,当电压较大时,温度是PEM电导率的主要影响因素。升高温度、增加液态水饱和度及降低膜厚均能有效提高电解池的性能。     

PEMFC碳纸气体扩散层内气液两相流格子Boltzmann模拟

为了提高质子交换膜燃料电池（PEMFC）水管理,本文借助多相流格子Boltzmann模型（LBM）模拟分析了PEMFC碳纸气体扩散层（GDL）内的气液两相输运过程,主要研究了GDL疏水性对气液两相流的影响。结果表明：液态水流路径不仅受到GDL结构形态的影响,而且受到材料疏水性影响。液态水在疏水性弱的GDL中不仅容易沁入,而且容易在孔隙中达到饱和;相反,在疏水性较强的GDL中,液态水很难突破沁入小尺寸孔隙,而从孔径较大的孔隙流通,从而形成毛细力主导的指进流动。     

质子交换膜燃料电池建模及水热传输特性分析

针对质子交换膜燃料电池(PEMFC)水管理开展了研究,建立了一维非等温两相流解析模型,研究了不同电流密度、微孔层接触角和不同加湿方案对电池内部水分布和温度分布的影响,提出了更好的进气加湿方案。结果表明:电流密度增大会导致阳极拖干、阴极水淹加剧,导致电池各部分温度上升。因各层材料亲水性不同,在交界面处能观察到液态水阶跃现象。增大微孔层接触角促进阴极液态水反扩散到阳极,一定程度上缓解阳极变干,但过大的接触角可能导致阴极水淹加剧。通过采取"阳极充分加湿、阴极低加湿"的进气加湿方案可以有效提高电池性能,并且能在一定程度改善电池内部受热,提高电池使用寿命。     

不同材料作为阳极扩散层对质子交换膜水电解池性能的影响

文章分别选用钛毡、烧结钛板与碳纸作为阳极气体扩散层,组装单节质子交换膜水电解池,并进行极化曲线和稳定性测试,以及交流阻抗测试和物理表征。研究结果表明:在常压,60℃的条件下,钛毡具有最好的电解性能;在电流密度为2.0 A/cm~2的稳定性测试中,烧结钛板扩散层、钛毡扩散层和碳纸扩散层的衰减率分别为65,73,386 mV/h;钛毡更适合作为质子交换膜水电解池的阳极扩散层。     

两相格子Boltzmann方法模拟大密度比下双液滴冲击液膜的流动过程

基于两相格子Boltzmann模型,对大密度比下有一定水平间距的双液滴冲击液膜的流动过程进行了仿真,模拟了不同液滴初始间距和不同雷诺数下液滴冲击液膜的动态过程,重点分析了不同液滴初始间距和雷诺数下产生不同冲击和溅射现象的原因,以及不同参数对冲击和溅射行为的影响.总结了中心位置水花溅射高度随时间的变化规律,并论述了冲击和溅射过程中的内在作用机理.结果表明:在一定范围内,初始间距和雷诺数越大,中心位置水花溅射高度上升越快;随着雷诺数的增大,冲击、碰撞的程度越剧烈,中心位置水花顶端有液滴飞出.     

模拟PEM燃料电池环境下质子交换膜损伤研究

该文研究在模拟燃料电池环境下的质子交换膜（PEM）材料的损伤情况。选用2种溶液模拟质子交换膜燃料电池（PEMFC）环境,一种是接近燃料电池实际运行环境溶液,称为正规溶液（RS）,另一种则为加速试样老化的加速持久性（ADT）溶液。采用衰减全反射傅里叶变换红外光谱（ATR-FTIR）和X射线光电子能谱（XPS）技术对老化试样表面的化学成分变化进行研究;同时,采用机械拉伸性能试验对老化前后试样进行研究。试验结果表明,在模拟PEMFC环境下,随着老化时间的增加,试样表面分子结构和化学成分发生明显变化,抗拉强度和断裂伸长率降低,试样材料损伤加剧。     

离子污染对质子交换膜电解制氢的影响研究进展

质子交换膜(proton exchange membrane,PEM)电解制氢运行灵活,具有优异的可再生能源波动适应性,是极具发展前景的绿色制氢技术。然而,在实际PEM电解制氢运行过程中,可能存在离子污染,对PEM电解堆的性能以及运行寿命产生很大影响。为此,首先分析了离子污染的来源,一方面来自水中的残余金属阳离子,如Na⁺、Ca²⁺、Mg²⁺等,另一方面来自电解堆内部关键材料和系统水循环管路因化学或电化学腐蚀产生的痕量金属离子,如Fe³⁺、Cu²⁺、Ni²⁺等;然后综述了不同离子污染对电解性能的影响,包括欧姆过电位、阴极反应过电位与阳极反应过电位;最后,综述了离子污染缓解策略,即如何避免规模化电解制氢过程中杂质离子污染带来的能效和成本问题。     

小型质子交换膜燃料电池的增湿技术研究

分析了PEMFC电池内部水的生成和转移过程，列举了各种增湿方法，指出了几种外增湿法对小型氢空质子交换膜燃料电池进行增湿的优缺点和对电池性能的影响。     

质子交换膜燃料电池专用碳纸的制备及性能测试

采用湿法造纸技术制备质子交换膜燃料电池电极扩散层专用碳纸材料,考察了影响专用碳纸性能的主要因素。研究结果表明：分散剂、粘合剂和纤维长度等对碳纸物性具有较大影响。以3M的NaOH处理碳纸的基体材料,控制打浆度20°SR,按比例加入自制功能性分散剂,在优化工艺条件下,制备的碳纸物性基本和日本东丽公司产品(Toray碳纸)物性相同。以自制的碳纸和Toray碳纸为电极扩散层基体材料组装成电池,放电性能测试表明,自制碳纸是一种较为理想的燃料电池电极扩散层基体材料。     

质子交换膜燃料电池的气体扩散层渗透率分形模型

本文提出了质子交换膜燃料电池（PEMFCs）气体扩散层（GDL）分形渗透率模型。这个模型是根据扩散层真实微观结构中的两个分形维数建立的。其中一个与毛细管流通道大小有关,另一个与通道迁曲度的描述有关。此外,气体分子的影响可以通过Adzumi方程计算。渗透率分形模型是多孔介质迁曲度分形维数、孔隙面积分形维数、孔径以及有效孔隙度的函数,模型中没有任何经验常数,可以用压汞法测量扩散层的微观结构。根据扫描电子显微镜图象,可用盒式维数法确定两个分形维数。为了检验模型的正确性,把该模型渗透率的预测数据与Toray提供的实验数据进行对比,发现该模型的渗透率预测与实验数据一致,证实了气体扩散层的分形渗透率模型的正确性。     

不同流道质子交换膜燃料电池内传质过程的数值模拟

对采用交指型流场的质子交换膜燃料电池阴极建立了二维数学模型,利用计算流体力学的方法,模拟和研究了质子交换膜燃料电池阴极内的流动和传质过程.分别探讨了采用交指型流场和平行流场时气体在阴极扩散层中的传递机制及各组分浓度分布的特性,为燃料电池流场的设计与分析提供了参考依据.     

格子Boltzmann方法的竖壁汽液降膜数值研究

对原有的格子Boltzmann伪势模型进行了改进,提出表面张力可调的伪势模型,并基于改进后的伪势两相模型在二维条件下模拟了雷诺数为5、10和20时竖壁降膜的流动,进一步研究了液膜在入口处存在正弦扰动时的流动特性,分析了入口扰动和表面张力作用对液膜稳态波动的影响,总结了液膜稳态波动的规律.结果表明:数值计算得到的流形拓扑及波动特征与实验结论能较好地吻合,表明伪势模型能够较为真实地反映降膜流动的物理过程.     

Evaluating Breakthrough Pressure in Gas Diffusion Layers of Proton Exchange Membrane Fuel Cells

This paper studied the breakthrough pressure for liquid water to penetrate the gas diffusion layer(GDL) of a proton exchange membrane fuel cell(PEMFC).An ex-situ testing was conducted on a transparent test cell to visualize the water droplet formation and detachment on the surface of different types of GDLs through a CCD camera.The breakthrough pressure,at which the liquid water penetrates the GDL and starts to form a droplet,was measured.The breakthrough pressure was found to be different for the GDLs with...     

Predicting transport parameters in PEFC gas diffusion layers considering micro‐architectural variations using the Lattice Boltzmann method

A deep understanding of the behavior of microstructural parameters in proton exchange fuel cells (PEFCs) will help to reduce the material cost and to predict the performance of the device at cell scale. Changes in morphological configuration, that is, fiber diameter and fiber orientation, of the gas diffusion layers (GDLs) result in variations of fluid behavior throughout the layer, and therefore, the microstructural parameters are affected. The aim of this study is to analyze, for three selected fiber diameters and different percentage presence of inclined fibers, the behavior of the different microstructural parameters of the GDLs. This study is carried out over digitally created two‐dimensional GDL models, in which the fluid behavior is obtained by means of the lattice Boltzmann method. Once the fluid behavior is determined, the microstructural parameters, that is, the porosity, gas‐phase tortuosity, obstruction factor, through‐plane permeability, and inertial coefficient, are computed. Several relationships are found to predict the behavior of such parameters as function of the fiber diameter, presence of inclined rods, or porosity. The results presented in this work are compared and validated by previous theoretical and experimental studies found in the literature. Copyright © 2016 John Wiley & Sons, Ltd.     

喷油嘴喷孔内气液两相流动的三维模拟

应用AVLFIRE软件,对5孔喷油器采用液体挤压研磨前后状态进行了二相流的三维流动计算。在喷油器针阀最大升程条件下,针对不同进口压力方案进行了两种喷油器的对比分析。计算结果表明:液体挤压研磨喷油器喷孔入口的圆角,有效地抑制了气穴的生成,从而提高了喷油器的流量系数。     

Simulation on water transportation in gas diffusion layer of a PEM fuel cell: Influence of non-uniform PTFE distribution

Proton exchange membrane fuel cells (PEMFCs) are promising clean power sources with high energy conversion efficiency, fast startup, and no pollutant emission. The generated water in the cathode can cause water flooding of the catalyst layer (CL), which in turn can significantly decrease the fuel cell performance. To address this significant issue of PEMFC, a new gas diffusion layer (GDL) with non-uniform distribution of PTFE is proposed for water removal from the CL. The feasibility of this new GDL design is numerically evaluated by a Lattice-Boltzmann Method (LBM)-based two-phase flow model. The porous structure of the new GDL design is numerically reconstructed, followed by LBM simulations of the water transport in GDL. Three types of different wetting conditions are considered. It is found that liquid water transported 7.87% more with a single row of wetted solids and 13.36% more with two rows of wetted solids. The results clearly demonstrate that the liquid water can be effectively removed from the GDL by proper arrangement of hydrophilic solids in the GDL.     

Compress effects on porosity,gas‐phase tortuosity,and gas permeability in a simulated PEM gas diffusion layer

Among the parameters to take into account in the design of a proton exchange membrane fuel cell (PEMFC), the energy conversion efficiency and material cost are very important. Understanding in deep the behavior and properties of functional layers at the microscale is helpful for improving the performance of the system and find alternative materials. The functional layers of the PEMFC, i.e., the gas diffusion layer (GDL) and catalyst layer, are typically porous materials. This characteristic allows the transport of fluids and charges, which is needed for the energy conversion process. Specifically, in the GDL, structural parameters such as porosity, tortuosity, and permeability should be optimized and predicted under certain conditions. These parameters have effects on the performance of PEMFCs, and they can be modified when the assembly compression is effected. In this paper, the porosity, gas‐phase tortuosity, and through‐plane permeability are calculated. These variables change when the digitally created GDL is under compression conditions. The compression effects on the variables are studied until the thickness is 66% of the initial value. Because of the feasibility to handle problems in the porous media, the fluid flow behavior is evaluated using the lattice Boltzmann method. Our results show that when the GDL is compressed, the porosity and through‐plane permeability decrease, while the gas‐phase tortuosity increases, i.e., increase the gas‐phase transport resistance. Copyright © 2015 John Wiley & Sons, Ltd.     

PEMFC分布式发电系统动态协调控制仿真

符号表m-质量/kg W-质量流量/kg·s-1N-电池个数I-电流/AM-摩尔分子质量F-法拉第常数/kg·mol-1/9.6 487×104C·mol-1R-气体常数/J·(mol·K)-1T-温度/KV-体积/m3A-反应面积/m2nd-电渗透系数Dw-扩散系数/m2·s-1cwa、cwc-膜阳极侧和阴极tm-膜厚度/m侧的水浓度/mol·m-2kp-水力