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

为了实现聚合物电解质燃料电池的实用化和高性能，对液气两相流经微尺度多孔材料进行了压降实验和行为观察，并基于物理模型对流经电极扩散层的水、液、气和含氧空气和蒸汽的两相流进行了数值分析。取得了以下研究成果：1.为了估算压降，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。根据扩散层的孔容分布数据确定了每种基材和防水材料的孔洞百分比。基于对气体单相流压降的测量，确定了每种基材和防水材料的绝对渗透率。结果表明，水分含量对…几乎没有影响气体单相流压降较大。通过对气液两相流动的测量，得到了气液两相的相对渗透率。然后，发现微尺度多孔材料的相对渗透率比传统的Wyllie方程计算值要低得多。用Burdine方程较好地再现了基材和疏水部分的液、气相相对渗透率，并根据孔径分布数据估算了各相的毛细压力。测量了每种基材和防水材料的接触角。数值分析结果表明，在基材与拒水材料部分的交界处形成了水分的蒸发，由于基材部分的饱和程度较大，氧的扩散容易受阻。此外，研究表明，尽管可以通过使防水材料的孔分布接近于基部来减小基部饱和度，但不可能在聚合物电解质膜中保持足够的水分。较少

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