| 摘要: | 本研究利用COMSOL Multiphysics建構一個三維、非等溫模型，探討陰陽極皆使用多孔傳輸層作為流道的陰離子交換膜水電解單元。該模型耦合了兩相流、物種傳輸、電化學反應、離子和電子傳輸與熱傳。首先對水電解單元內部進行傳輸現象分析，包括陰極流域中的兩相體積分數分佈及熱傳分析，接著對影響水電解性能的各種因素進行參數分析，包含幾何參數、材料性質及操作參數，得出不同參數對電流密度與液體消耗的影響，以及比較2V下之氣體分佈結果，並且對參數影響電解性能之原因進行說明解釋。
由傳輸現象分析結果發現，隨著電壓增加，流道中平均H_2體積分數逐漸上升，從1.4V上升至2V，於流道出口截面之H2體積分數增加約2.8倍。此外，從陰極流域出口截面可發現H_2傾向於積聚在肋條下方的觸媒層邊緣。從溫度分佈結果可得知陽極因O_2氣泡密度較大且析氧反應有較高的過電位，因此陽極溫度的上升幅度會比陰極更顯著。此外，參數分析結果表明，提高流道孔隙率、膜含水量、操作溫度與 KOH 入口流速皆能使水電解性能提升。
;This study utilizes COMSOL Multiphysics to construct a three-dimensional, non-isothermal model to investigate an anion exchange membrane water electrolysis unit, wherein both the anode and cathode utilize porous transport layers as flow channels. The model integrates two-phase flow, species transport, electrochemical reactions, ion and electron transfer as well as heat transfer. Initially, an analysis of transport phenomena within the electrolysis unit is performed, including the distribution of two-phase volume fractions in the cathode flow field and thermal analysis. Subsequently, a parametric analysis of various factors affecting the performance of water electrolysis is conducted. This includes geometric parameters, material properties, and operational parameters, examining their impact on current density and liquid consumption, as well as comparing gas distribution results at 2V, and elucidating the reasons for these parameter effects on electrolysis performance.
From the transport phenomena analysis, it was found that as the voltage increases, the average H₂ volume fraction in the flow channels gradually rises, increasing approximately 2.8 times from 1.4V to 2V at the channel exit cross-section. Additionally, it is observed at the cathode flow field exit cross-section that H₂ tends to accumulate at the edges of the catalyst layer beneath the ribs. From the temperature distribution results, it is evident that the anode temperature increases more significantly than the cathode due to a higher density of O₂ bubbles and a higher overpotential of the oxygen evolution reaction. Moreover, the parametric analysis indicates that enhancing the porosity of the flow channels, membrane water content, operational temperature, and KOH inlet flow rate can all improve the performance of water electrolysis. |
