成果報告書詳細
管理番号20090000000605
タイトル*平成20年度中間年報 固体高分子形燃料電池実用化戦略的技術開発 次世代技術開発 粒子法を用いた直接シミュレーションによる流路・拡散層内のガス・水滴輸送挙動の研究
公開日2010/3/2
報告書年度2008 - 2008
委託先名みずほ情報総研株式会社
プロジェクト番号P05011
部署名燃料電池・水素技術開発部 燃料電池グループ
和文要約以下本編抜粋:1. 研究開発の内容及び成果等 1.1 研究目標 粒子法を用いた直接シミュレーションによって、拡散層のミクロな空孔構造レベルで適用可能な二相流動解析シミュレーション技術を確立するとともに、運転・構造条件に対する流路・拡散層内の多様な流動様式を解明し、固体高分子形燃料電池の性能向上に対する最大の課題の一つであるガス・水滴挙動の解明を目指すことを目的とする。
英文要約It is important to control the behavior of liquid water inside Polymer Electrolyte Fuel Cells (PEFCs), which cause a significant decrease of the cell performance (the so-called "flooding phenomena"). However, it is quite difficult to observe liquid water inside the microscopic structures of the gas diffusion layer. Two major missions of this project by the end of 2009 are:(1) Investigation of the gas and liquid water transport inside the gas diffusion layer and the micro porous layer by direct numerical simulation. (2) Classification of two-phase flow pattern inside the flow channel and on the surface between the flow channel and the gas diffusion layer by direct numerical simulation using moving particle semi-implicit (MPS) method as well as experiment and the validation of numerical simulation compared to the experimental data. In this year (2008), as for mission (1), we carried out a fundamental investigation that dissipative particle dynamics (DPD) method has a potential to calculate the specific phenomena inside the submicron scale pore such as evaporation and condensation by Kelvin’s effect and slip-flow effect of gas near the solid wall. Using the this method, we calculated macroscopic viscosity for two cases of liquid water flow in a 10nm channel, non-equilibrium shear flow and parallel plate flow with gravity force. As a result, both cases of the shear rate near the wall are increased compared to theoretical solution, that is, slip-flow effect. As for mission (2), the scheme for understanding the behavior of liquid water transport by both the direct numerical simulation and the measurement inside a straight flow channel cell is designed. In this scheme, two-phase flow pattern inside a flow channel including the gas diffusion layer can be solved by the simulation, and velocity and diameter of liquid water droplet, pressure increase inside a channel of test cell and the cell performance are measured at the same time by the experimental implement which consists of same components, transparent cell, microscope, pressure sensor and PTV measurement device. Consequently, we got possible to analyze the effect of liquid water removal on the cell performance by comparing an experimental result with a simulation result under the same structural and operating condition. As an example, the effect of wettability and depth of a flow channel on the removal of liquid water is investigated by both the simulation and the experiment and we confirmed that liquid water is removed in the case of hydrophilic and shallow channel much better in other case under the condition of low gas velocity. This is reason that liquid water discharged from the gas diffusion layer is soaked up to the bottom of channel by hydrophilic capillary force and dragged easily toward the outlet of channel.
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