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

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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