Higher load current of PEMFC

质子交换膜燃料电池的性能在很大程度上取决于其水管理。气体扩散层（GDL）和催化剂层（它们是要管理的主要目标）中出现的溢流难以测量和/或观察，因为这些层被归类为基于碳的微孔介质和不透明材料。另一方面，质子交换膜燃料电池内气液两相流数值模拟也是近年来发展起来的。在模拟过程中，MM模型，这是一个数学模型来处理两相现象的多孔介质，如GDL，似乎成功地模拟了细胞操作过程中的洪水。然而，模拟的评价是不够的。只有评价是基于模拟和实验之间的IV特性的比较。模拟的气液两相现象，如气液两相饱和度等，还没有实验结果来评价，本文采用间接法测量了气液两相饱和度，并与实验结果进行了比较 ...更多信息 结果与模拟结果一致。我们制作了一个简单的交叉指型池，其中所有流体在GDL中强制流动，并通过GDL测量压差，并从其压差估计含水饱和度比。在数值模拟中，我们基于MM模型建立了完整的守恒方程，并在边界条件下考虑了叉指单元。在模拟中，我们还进行了负载电流阶跃变化的瞬态计算，在测量中，电池电位在负载电流超过0.5A/cm ~ 2时显著下降。我们成功地解释了这种下降是由浓度超过电位并伴随着估计的含水饱和度引起的。随着负载电流、加湿温度和气体利用率的增加，含水饱和率增加。这些操作条件是控制GDL液泛的关键参数。模拟的IV特性成功地再现了测量的IV特性。但在大电流区不能显示出浓差过电位。从模拟得到的压差定性与测量数据在15%以内。在瞬态计算中，电池电位变化复杂。我们可以用几个时间常数来解释这一点，这些时间常数对应于细胞中进行的传输现象。少

The performance of PEMFC largely depends on its water management. The flooding appeared in gas diffusion layer (GDL) and catalyst layer, which are main target to be managed, is difficult to measure and/or observe, because these layers are categorized as micro-porous media and opaque material based on carbon. On the other hand, the gas-liquid two-phase flow numerical simulation in PEMFC is developed recently. In this progress of simulation, the MM model, which is one of mathematical model to treat two-phase phenomena in porous media such as GDL, seems to successfully simulate the flooding during cell operation. However the evaluation of the simulation is not enough. Only the evaluation is based on the comparison of IV characteristic between simulation and experiment. The simulated two-phase phenomena, such as the water saturation ratio in GDL, have not been evaluated with experimental result.In this study, we measured the water saturation in GDL with indirect method and compared its res … More ult with that obtained from simulation. We fabricated a simple interdigitated cell where the whole fluid flows forcedly in GDL, and measured the differential pressure through GDL, and estimated the water saturation ratio from its differential pressure. In numerical simulation, we formulated the full conservation equations based on MM model, and executed with the boundary condition considering the interdigitated cell. In simulation we also executed the transient calculation in which the load current changed step-wisely.In measurement, the cell potential decreased significantly over 0.5A/cm2 load current. We successfully explained that this drop was caused by the concentration over potential accompanied with the water saturation estimated. The water saturation ratio increased with higher load current, humidification temperature, and gas utilization ratio. These operation conditions are noted as the key parameter to control the flooding in GDL. The simulated IV characteristics succeeded to reproduce the measured. But they could not show the concentration overpotential appeared in high current region. The differential pressure obtained from the simulation qualitatively agreed with the measured data within 15%. In transient calculation, the cell potential changed complexly. We could explain this with several time constant corresponding to the transport phenomena being progressed in cell. Less