氣體擴散層雙側微孔層塗佈對質子交換膜燃料電池性能影響計算分析

Abstract

本論文以數值模擬軟體COMSOL Multiphysics建立二維兩相流陰極側質子交換膜燃料電池模型。模型元件包含氣體擴散層及雙側微孔層，並以連續方程式、動量方程式及物種守恆方程式等理論分析研究燃料電池。 當燃料電池操作於高電流密度時，陰極觸媒層側會產生液態水，若液態水無法從觸媒層排出，水氾濫的現象就會發生。水氾濫現象將限制氧氣的質傳特性，同時也降低了燃料電池的性能。 解決此問題的關鍵技術就在於如何在燃料電池內有效的水管理，確保燃料電池各處都能達到水平衡。利用陰極側氣體擴散層雙側塗佈微孔層，變化其接觸角、孔隙率及碳粉當量，探討此時燃料電池的液態水分布以及對於電池性能的影響。結果發現，氣體擴散層塗佈雙側微孔層時，搭配上孔隙率高、接觸角低的微孔層能有效增強其液態水及氣體的傳輸，並強化其排水性進而提升燃料電池的性能。

In this study, a two-dimensional two-phase proton exchange membrane fuel cell model is built by the finite element simulation software ─ COMSOL Multiphysics. The model is composed of gas diffusion layers with double micro-porous layers. The theory which use to analyze the model includes continuous equation, momentum equation and species conservation equation. When the fuel cell is operated at high current density, the liquid-water is generated in the cathode catalyst layers. If liquid-water cannot flow out of the cathode catalyst layer, 'Flooding' will appear. The flooding phenomenon limits the transportation of oxygen and also destroys the performance of the fuel cell. The key point of solving this problem is to improve the management of water in order that the amount of liquid-water in the fuel cell can be appropriately controlled. The use of double micro-porous layers is a potential efficient way to achieve this goal. To identify the impacts of the saturation distribution on the performance of the fuel cell, this paper studies the effect of micro-porous layer by changing its contact angle, porosity and carbon loading. Results show that the double micro-porous layers of high porosity and low contact angle with gas diffusion layer can enhance the transportation of reactant gases and liquid-water, elevating the functions of removing liquid-water and improving the performance of fuel cell.