共查询到16条相似文献,搜索用时 78 毫秒
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交指状流场质子交换膜燃料电池的流动特性 总被引:1,自引:0,他引:1
不同流场构型对质子交换膜燃料电池的流动特性和电池效率有重要的影响,因此流场的设计和理论研究是质子交换膜燃料电池研究的重要课题.发展了一个基于计算流体力学的稳态的三维数学模型,应用建立的模型对一个交指状流场设计的质子交换膜燃料单电池进行了数值研究,电池的电极面积大小为6.4×6.5 cm2,计算得到了电池的流场、局部电流密度和组分浓度等的空间分布,分析了其流动特性和传输机理. 相似文献
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为深入研究质子交换膜燃料电池内电荷传递的规律,发展了一个三维的单相流、非等温数学模型,模型考虑了电子在催化层和扩散层、质子在催化层和质子交换膜中的传递。通过计算得到了电池内电位和电流密度的空间分布,分析了不同电极结构参数下电流密度的分布和最终造成的性能差异。结果表明,欧姆电位的下降主要发生在膜相电位,而碳相电位的下降几乎可以忽略不计;电流密度在流道与集电极交界处出现"火焰形"累积效应;改变电池的结构对电池性能影响不大,应结合加工成本和电流密度分布综合考虑。 相似文献
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质子交换膜燃料电池自增湿研究进展 总被引:3,自引:0,他引:3
概述了质子交换膜燃料电池自增湿研究状况,指出自增湿的出发点是有效利用电池阴极过程生成水。综述了薄电解质膜、新型自增湿膜、自增湿流场结构三种方法的研究进展及适用空间。对自增湿技术发展前景进行了探讨。 相似文献
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针对直流道质子交换膜燃料电池阳极,建立二维稳态的数学模型研究流道和电极内的流动和传质特性。模型采用通用Darcy定律来描述多孔介质与非多孔介质区域的流体流动,可以模拟沿流动方向上的物质变化情况,并探讨进口速度、进口氢气质量分数和催化层厚度对质量传输的影响。结果表明:增大进口速度、增加进口氢气质量分数、降低催化层厚度有利于氢气的质量传递。 相似文献
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质子交换膜燃料电池(PEMFC)引射器设计通常需经过结构参数计算、计算域建模、网格划分和数值模拟等步骤,并经过多轮迭代得到一个性能较优的设计方案,所需时间成本较高。针对PEMFC引射器,通过Python编程语言将以上功能进行集成,自动计算引射器结构参数,并调用OpenFOAM软件中的blockMesh工具进行计算域建模、网格划分,以及rhoSimpleFoam求解器进行数值仿真验证,形成一套参数化的自动仿真设计工具。研究表明,该工具可显著提高PEMFC引射器设计开发的速度,从而促进汽车工业的发展。 相似文献
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《International Journal of Hydrogen Energy》2020,45(53):29331-29344
In proton exchange membrane fuel cells (PEMFC), the design of the cathode flow field is very important, because an excellent flow channel design can not only accelerate the transmission rate of liquid water, but also affect the distribution of electrode reactants and electrode products which influence the electrochemical performance of the fuel cell. This study presents three new channels (models 1,2 and 3), which were created using two unilateral slopes and a bilateral slope structure with tapered tube lengths of 0.4, 1.2 and 0.8 mm, respectively. The dynamic behavior of liquid water under the three design schemes is numerically studied based on the volume of fluid method. And the influence on the performance of fuel cell was analyzed synthetically. The results indicate that the introduction of a tapered and sloping structure can improve the transmission efficiency of the droplets in the flow channel, and the maximum droplet removal time of the new channel can be reduced by 24.4%compare with standard conventional flow channel. The slope structure guides the flow path of water droplet and reduces the occurrence of droplet spatter. Influenced by the slope and tapered structures, the turbulence of airflow near the bottom surface (gas diffusion layer)of the flow channel is enhanced and Oxygen concentration in the cathode is raised, which improves the mass transfer capacity and average current density of reactive surface. In conclusion, the new type of channel with a tapered and sloping structure has a potential to improve the performance of water management in the cathode channel of PEMFC. 相似文献
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PEMFC系统引射器设计及仿真研究 总被引:1,自引:0,他引:1
针对燃料电池汽车的运行特点,对氢气循环引射器进行了结构设计,利用Fluent软件对所设计的引射器进行了全工况模拟,确定了对引射器效率影响较大的变量。通过改变工作流体流量,并经过多次模拟后发现,为了使氢气引射器在怠速工况下不失效,引射器前端工作流体压力p_p要≥1.05 MPa。分析了工作流体质量流量G_p、喷嘴喉部直径d_(p*)和工作流体压力p_p对引射性能的影响,发现G_p对引射器的引射性能影响最大,并给出了G_p的取值范围。研究建议引射器设计时G_p在0.21~0.23 g·s~(-1)范围内最佳。 相似文献
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Influence of anisotropic gas diffusion layers on transport phenomena in a proton exchange membrane fuel cell 下载免费PDF全文
The gas diffusion layer is an anisotropic porous medium, which provides pathways for the reactant gases and produced water, conducts the electrical current, removes the generated heat, and provides mechanical support. However, the gas diffusion layer is mostly considered as isotropic in numerical simulations. In the present study, a three‐dimensional, two‐phase flow, and non‐isothermal agglomerate model with consideration of anisotropic permeability, mass diffusivity, thermal conductivity, and electrical conductivity was developed and employed to investigate effects of anisotropic properties on the transport phenomena in a proton exchange membrane fuel cell. The temperature of the anisotropic case is less than that of the isotropic case, and the temperature difference increases with increasing current density. Furthermore, the distributions of the oxygen mass fraction, liquid water saturation, water content, and local current density for both cases are also compared and discussed in detail. The cell performance is over‐predicted by the isotropic model, and the current density of the isotropic case is greater than that of the anisotropic case by approximately 10% at an operating cell voltage of 0.3 V. Both the local transport characteristics and overall cell performance are different for the isotropic and anisotropic cases. Accordingly, it is concluded that the anisotropic properties of the gas diffusion layer must be taken into account in the mathematical model. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Proton exchange membrane fuel cell (PEMFC) performance degrades when carbon monoxide (CO) is present in the fuel gas; this is referred to as CO poisoning. This paper investigates CO poisoning of PEMFCs by reviewing work on the electrochemistry of CO and hydrogen, the experimental performance of PEMFCs exhibiting CO poisoning, methods to mitigate CO poisoning and theoretical models of CO poisoning. It is found that CO poisons the anode reaction through preferentially adsorbing to the platinum surface and blocking active sites, and that the CO poisoning effect is slow and reversible. There exist three methods to mitigate the effect of CO poisoning: (i) the use of a platinum alloy catalyst, (ii) higher cell operating temperature and (iii) introduction of oxygen into the fuel gas flow. Of these three methods, the third is the most practical. There are several models available in the literature for the effect of CO poisoning on a PEMFC and from the modeling efforts, it is clear that small CO oxidation rates can result in much increased performance of the anode. However, none of the existing models have considered the effect of transport phenomena in a cell, nor the effect of oxygen crossover from the cathode, which may be a significant contributor to CO tolerance in a PEMFC. In addition, there is a lack of data for CO oxidation and adsorption at low temperatures, which is needed for detailed modeling of CO poisoning in PEMFCs. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Vilasinee ThitakamolApichai Therdthianwong Supaporn Therdthianwong 《International Journal of Hydrogen Energy》2011,36(5):3614-3622
A new design of an interdigitated flow field, called as a mid-baffle interdigitated flow field, was built and tested for its effect on the performance of proton exchange membrane (PEM) fuel cells. The results were compared to the conventional interdigitated flow field. Their performances at different oxidant gas flow rates and operating pressures were also examined and compared by using both O2 and air as the cathode fuel reactants. The experimental results showed that when air was used as the cathode reactant, the cell with the mid-baffle interdigitated flow field outperformed the conventional one, giving a power output approximately 1.2-1.3 times higher depending on the air flow rates. The polarization curves of the mid-baffle interdigitated flow field showed larger limiting current densities at every air flow rate tested in this work. However, the performances of both flow fields were almost the same when the cathode reactant gas was O2. The test also demonstrated that the flow field performance could be enhanced by increasing the oxidant gas flow rate and cell operating pressure. 相似文献