Development of an Analysis Model for Thermal Hydraulics on a Liquid and Gas Two-phase Flow through a Microscale Porous Material

为提高聚合物电解质燃料电池的利用率和高性能，对液体和气体两相流过微尺度多孔材料的压降实验和行为观察，以及基于物理模型的水、液、气两相流过电极扩散层的含氧空气和蒸汽进行了数值分析。得到了以下结果：对于压降的估算，有必要将扩散层分为基材和构成扩散层的防水材料两部分。根据扩散层孔隙体积分布数据，确定了基材和防水性材料的孔隙率。根据气体单相流压降的测量，确定了基材和防水材料的绝对渗透率。结果表明，含湿量对气体单相流的压降几乎没有影响。通过对液、气两相流动的测量，得到了液、气两相的相对渗透率。然后，发现微尺度多孔材料的相对渗透率与常规使用的威利方程计算值相比要低得多。根据孔径分布数据估计出的各相毛细管压力，用伯丁方程很好地再现了碱类和疏水性部件的液相和气相相对渗透率。测定了基材和拒水剂的接触角。数值分析结果表明，在基材与拒水剂部分的边界处形成了水分的蒸发，基材部分饱和度大，容易阻碍氧气的扩散。此外，研究表明，拒水材料的孔隙分布接近于基材的孔隙分布，虽然可以减小基材的饱和度，但在聚合物电解质膜中不可能保持足够的水分。少

For utilization and high-performance of a polymer electrolyte fuel cell, experiments on pressure drop and observation of behavior were carried out for liquid and gas two-phase flow through a microscale porous material and beside a numerical analysis was performed based on physical model, aimed at the two-phase flow of water liquid and gas of air and steam containing oxygen which flows through an electrode diffusion layer. The following results were obtained.1. For the estimation of the pressure drop, it is necessary to divide the diffusion layer into two parts of base material and water repellent material constituting it. Percentage of void for each of base and water repellent materials was determined from pore volume distribution data of the diffusion layer.2. Absolute permeability was determined for each of base and water repellent materials based on measurements of the pressure drop of a gas single-phase flow,.3. It was found that there was almost no effect of moisture content on th … More e pressure drop of the gas single-phase flow.4. Based on measurements of a liquid and gas two-phase flow, relative permeabilities of liquid and gas phases were obtained. Then, relative permeability of microscale porous material was found to be quite lower compared with the value calculated by the Wyllie equation used well conventionally.5. Relative permeabilities of liquid and gas phases for base and water repellent parts were reproduced well by the Burdine equation with capillary pressure of each phase estimated from the pore size distribution data.6. Contact angle was measured for each of base and water repellent materials.7. As the results of numerical analysis, it was found that evaporation of water was formed on the boundary between base and water repellent material parts, and that diffusion of the oxygen was easily blocked due to large saturation of the base material part. In addition, it was shown that, although the base part saturation could be made small by bringing pore distribution of the water repellent material close to that of the base part, it becomes impossible to hold moisture sufficient in the polymer electrolyte film. Less