質子交換膜燃料電池陰極氣體擴散層及微孔層內的兩相流傳輸分析

Abstract

微孔層是加在氣體擴散層與觸媒層之間，主要功用是藉由毛細作用力幫助液態水的排除。當質子交換膜燃料電池在高電流密度時，化學反應所生成的液態水會阻礙氣體燃料的傳輸，使電池的性能大幅降低，而且陰極所受的影響遠比陽極大。本文研究針對質子交換膜燃料電池陰極氣體擴散層與觸媒層內的兩相流傳輸現象，利用數值模擬求解出內部液態水飽和度的分佈、氧氣濃度的分部以及極化性能曲線。 研究結果顯示在兩相流傳輸模式下，液態水會佔據孔隙，阻礙氧氣的傳輸，若在觸媒層與氣體擴散層之間加入微孔層，可以有效的幫助液態水排除，所以可傳達觸媒層的氧氣濃度得以增加，因此可以提升電池的性能。當微孔層的孔隙率越大、厚度越薄時，電池有越好的性能。

Micro porous layer (MPL) was added between gas diffuse layer and catalyst layer. The liquid water produced by chemical reaction would prevent from gas fuels transport, when the proton exchange membrane fuel cell (PEMFC) work in high current density. It would reduce performance substantially. The effects on cathode is more then in anode accord with literatures. The study focuses on transport phenomena of cathode gas diffuse layer and micro porous layer of PEM fuel cell by using two-phase flow model. Liquid water saturation and oxygen concentration profile in gas diffusion layer (GDL) and micro porous layer polarization curve are investigated by numerical simulations. Results show that liquid water would hold hole reducing oxygen concentration profile in two-phase model. With the increasing the porosity of MPL and reducing thickness, the cell performance become higher.