As for the liquid water content distributions, the liquid saturations in gas diffusion layers are shown in Fig. 6. For both case1 and case 2, the liquid water appears in the vapor saturation areas which locate between the mid area and cathode outlet area. For both cases, the cathode side exhibits apparent higher liquid water content than anode side does. Moreover, the liquid water accumulates in the porous media under the ribs rather than the gas channels, due to the elimination effects of liquid water in gas channels by convective flows. The maximum value of liquid saturation locates at the edge areas of cathode flow field without coverage by the wavy air channels where the oxygen supply is hindered by both blockage of liquid water in porous media and farther distance for gas permeation. The liquid water content of case 2 shows slightly higher than that of case 1, which is a result of tradeoff between operating temperature and pressure. Increasing temperature alleviates the condensation of water vapor, while the increased back pressure lowers volumetric gas flow rate and enhances liquid water accumulation inside the porous media.
时间: 2023-02-19 09:14:49 浏览: 108
就液水含量分布而言,气体扩散层中的液体饱和度如图6所示。对于case1和case2,液体水出现在蒸汽饱和区,位于中间区域和阴极出口区之间。对于这两种情况,阴极侧表现出明显比阳极侧高的液体水含量。此外,由于液体水在气体通道中被对流流动排除,液体水会积聚在空气通道下的多孔介质中而不是气体通道中。液体饱和度的最大值位于阴极流场的边缘区域,这些区域没有被波浪状的空气通道覆盖,在这里氧气供应受到液体水在多孔介质中的阻塞以及气体渗透的较远距离的双重影响。case2的液体水含量略高于case1,这是操作温度和压力之间的折衷结果。温度的升高减轻了水蒸气的凝结,而增加的背压降低了体积气体流量,增强了多孔介质中的液体水积聚。
相关问题
用中文翻译:The detailed temperature distributions under 1 A/cm2 for case 1 are shown in Fig. 11 as an example for analysis. In Fig. 11 (a), the inversely phased wavy flow channels for H2 and air are overlapped in the xz plane indicated with flow directions of each reactants’ channels. The rib areas for anode and cathode sides are also wavy shaped and intercrossed in the front view of xz plane. As a result, there are four kinds of zones in the MEA area when overlapping the anode and cathode flow fields: anode channel / cathode channel (AnC/CaC), anode channel / cathode rib (AnC/CaR), anode rib / cathode channel (AnR/CaC) and anode rib / cathode rib (AnR/CaR). For example, the red dashed line areas in Fig. 11 (a) indicates the AnR/CaR areas where the ribs of MBPP at both anode and cathode sides contact the MEA directly. Fig. 11 (b) shows the temperature distributions in the mid plane of membrane. The high and low temperature areas both present multiple elliptical island shaped distributions with the temperature range of 344 K–346 K. Besides, the calculated 2D temperature distributions in the mid plane of anode and cathode catalyst layers are similar to those in membrane with slight local temperature deviations.
结果,当重叠的阳极和阴极流场时,MEA区域有四种类型的区域:阳极通道/阴极通道(AnC/CaC),阳极通道/阴极肋(AnC/CaR),阳极肋/阴极通道(AnR/CaC)和阳极肋/阴极肋(AnR/CaR)。图11(b)显示了膜中间面的温度分布。高温和低温区域都呈现多个椭圆形岛状分布,温度范围为344 K-346 K。此外,计算出的阳极和阴极催化剂层中间面的2D温度分布与膜中间面的温度分布类似,但存在轻微的局部温度偏差。
用中文翻译:A coupled three-dimensional model is developed to study the internal parameter distributions of the MBPP fuel cell stack, considering fluid dynamics, electro-chemical reactions, multi-species mass transfer, twophase flow of water and thermal dynamics. The model geometry domains include anode MBPP, anode gas wavy flow field (5 parallel flow channels), anode GDL, anode catalyst layer (CL), membrane, cathode CL, cathode GDL, cathode gas wavy flow field (5 parallel flow channels), cathode MBPP and the two-layered coolant wavy flow fields at anode/cathode sides. According to the stack design, the design parameters of wavy flow fields for anode and cathode sides are the same but the phase deviation between their wave cycles presents 180◦. The two wavy flow fields of coolant, at the respective back sides of the anode and cathode plates, form the intercrossed two-layered coolant flow fields inside the MBPP, due to the phase difference of 180◦ between the wave cycles (Fig. 3). The mismatched flow field patterns between the neighbored fluid flows lead to complicated geometry and mesh building. The presented model geometry is divided into several layers (xz plane) according to the different domain materials so that the thin metallic plate and fluid domains with complicated 3D morphologies could be finely meshed layer by layer. As the real geometry of the experimental stack is too large for calculation, the modeled flow field consists of 5 parallel wavy channels, each of which includes 2 wave periods and corresponding inlet/outlet portions as well. To study the detailed thermal behavior of the presented design, the two-layered coolant fluid flow at the back side of the anode plate is considered and so is for the cathode plate. The counter flow operation is conducted where the air flows at the same direction with coolant but the opposite with hydrogen, shown in Fig. 3 (b).
研究MBPP燃料电池堆内部参数分布的三维耦合模型被建立,考虑流体力学、电化学反应、多物种质量转移、水的两相流动和热力学。模型几何域包括阳极MBPP、阳极气体波浪流场(5个平行流道)、阳极GDL、阳极催化层(CL)、膜、阴极CL、阴极GDL、阴极气体波浪流场(5个平行流道)、阴极MBPP和阳极/阴极两层冷却剂波浪流场。根据堆设计,阳极和阴极侧波浪流场的设计参数相同,但其波浪周期之间的相位偏差为180°。阳极板背面和阴极板背面的两个波浪流场形成交叉的两层冷却剂流场,由于波浪周期之间的相位差为180°(图3)。相邻流体流动之间的不匹配流场模式导致复杂的几何和网格构建。所提出的模型几何体根据不同的域材料分为几层(xz平面),以
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