金屬發泡材應用於質子交換膜燃料電池之兩相流場模擬分析;Numerical Study on Transport Phenomena in PEMFC with Metal Foam as Flow Distributor

NCU Institutional Repository > 工學院 > 機械工程研究所 > 博碩士論文 > Item 987654321/53855

請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/53855

題名:	金屬發泡材應用於質子交換膜燃料電池之兩相流場模擬分析;Numerical Study on Transport Phenomena in PEMFC with Metal Foam as Flow Distributor
作者:	蘇韋任;Su,Wei-Jen
貢獻者:	機械工程研究所
關鍵詞:	多孔性介質;數值模擬;燃料電池;兩相流;金屬發泡材;滲透率;當量比;porous media;numerical;stoichiometric;permeability;two phase;fuel cell;metal foam
日期:	2012-07-25
上傳時間:	2012-09-11 18:17:45 (UTC+8)
出版者:	國立中央大學
摘要:	本文為首次利用unsaturated flow theory ( UFT )兩相流理論，建立三維，穩態以及非等溫之質子交換膜燃料電池模型，討論兩相流理論應用於金屬發泡燃料電池數值模型之結果，與實驗數據相互對照討論模型之適用性，並且藉由改變流道設計、金屬發泡材滲透率、入口加濕溫度、陰極入口當量比以及氣體擴散層性質來探討不同的操作條件的流場特性以及對性能之影響。本文的模型包括集電板、流道、氣體擴散層、微孔層、觸媒層以及質子交換膜六層結構，以Darcy's model計算金屬發泡材應用於流道中以及氣體擴散層等多孔材質結構之流場；考慮陰極反應產生之水為氣態並且在流場中產生凝結相變，液態水在流場中的動態受氣體拖曳力與毛細壓力影響。透過商用求解器Fluent，並且藉由撰寫user define function ( UDF )達到計算兩相模型之需求。研究結果顯示目前模型在高電流密度操作條件下，凝結相變的量過小，導致在高電流密度下質傳限制的效應不明顯，因此較適用於低電流密度下的操作條件；在流道設計方面，金屬發泡材流道的性能優於蛇型流道，對稱型出入口設計對於性能無明顯之提升。而降低金屬發泡材滲透率可提升電池之性能，且主要由in-plane方向的滲透率影響，當滲透率小於氣體擴散層之滲透率時，性能有明顯之提升。模擬結果也顯示金屬發泡材燃料電池在入口加濕溫度與操作溫度相同時有最好的性能，當入口加濕溫度高於操作溫度時，液態水生成的量會過高導致性能之下降。另外也發現陰極入口之當量比提高可提高液態水排除的能力；在氣體擴散層結構方面，微孔層有助於液態水往氣體體擴散層方向擴散，但在水凝結量不大時，微孔層對於氧氣的擴散反而造成阻礙。The two-phase, three-dimensional, non-isothermal proton-exchange membrane fuel cell (PEMFC) model is first applied on PEMFC with metal foam as flow distributor in this study. Computational domain includes plate, flow channel, gas diffusion layer, micro porous layer, catalyst layer, and membrane. Darcy's model is employed in porous regions, and transport of liquid water inside the porous media is modeled using viscous forces and capillary pressure terms. Numerical results are compared with experimental data and the differences are discussed. Effects of various parameters, such as the type of channel, the permeability of metal foam, and operational parameters, are discussed. Results show that the condensation rate of current model is lower than expected, resulting in disparities with experimental data in the concentration polarization region. Therefore, the suggested operation condition is of high voltage. Cell with metal foam as flow distributor has more uniform and higher oxygen concentration distribution in diffusion layer than that with serpentine flow field, and therefore has higher current density. Increasing the number of the inlet within the metal foam channel only helps decrease the pressure drop. The in-plane permeability of metal foam plays dominant role in cell performance and current density increases significantly when the permeability of metal foam is lower than that of gas diffusion layer. Results also show that the most appropriate humidification temperature of inlet gas is to be same as the cell temperature, and a higher stoichiometry of inlet gas makes better removal of the liquid water in the gas diffusion layer, and results in better diffusion of oxygen.
顯示於類別:	[機械工程研究所] 博碩士論文

文件中的檔案:

檔案	描述	大小	格式	瀏覽次數
index.html		0Kb	HTML	398	檢視/開啟

在NCUIR中所有的資料項目都受到原著作權保護.

社群 sharing

資料載入中.....