新式微型直接甲醇燃料電池性能設計分析

Abstract

本研究係利用CFD-RC商業套裝軟體建構三維數值模型，對一種新式微型甲醇燃料電池進行數值模擬。其中，所考慮的理論包含流場、質量傳輸、以及電化學反應，並以有限體積法(Finite volume method)求解各統御方程式，探討在不同操作參數下，燃料電池系統內部之流場分佈、濃度場分佈以及電流密度之變化，進一步了解各參數對整體燃料電池效能之影響。研究結果顯示，電池性能受限於陰極氧氣傳輸能力，採用高流量、高氧氣濃度或是孔隙度、厚度較大的陰極觸媒可以有效提升電池之性能。此外，流道之幾何關係亦是本研究討論的重點，設計流道的長度及高寬比(Aspect ratio)，必須配合流量對其內電阻之影響，選用最佳之幾何外型。本研究之三維數值模型可作為未來最佳化之操作設計。

In this study, a design for a novel micro direct methanol fuel cell (μ-DMFC) has been investigated theoretically. The fuel and oxidant are methanol and oxygen, respectively, which both dissolved in dilute sulfuric acid solutions. This concept of structure is distinct the conventional bipolar plants where the anode and cathode streams are made by two separate substrates. The model is applied to simulate the species transport within the micro DMFC system and the cell performance is analyzed significantly by examining the considerable parameters such as the volumetric flow rate, concentration of reactants, catalyst layers, and channel geometry. The commercial CFD package, CFD-RC, is employed to perform the numerical simulation. These results reveal that the cell performance is mainly restricted by the cathode transport. The improved approach also can be presented on the influence of cell performance in detail.