操作參數和微孔層對直接甲醇燃料電池
性能之影響

摘要直接甲醇燃料電池，在能源轉換科技中，具有很大的潛力和前瞻性。然而其問題在於甲醇穿透的現象，會降低電池的性能。因此，本文探討操作參數和微孔層對直接甲醇燃料電池性能之影響，藉由計算流體力學軟體CFDRC 數值模擬來輔助探討。首先以基本架構之蛇行流道為基礎模型，改變操作參數（甲醇水溶液濃度、溫度、陽極流體速度與陰極流體壓力）所得到的結果來進行分析比較。再加入一微孔層於陽極的電極板與擴散層之間，瞭解微孔層對甲醇穿透和電池效能之影響。模擬結果顯示，較佳甲醇水溶液的濃度為2M，能有效的使用燃料；在陽極入口流速方面，流速約為0.01m/ s 時，燃料所擴散參與反應的使用率為較佳；陰極流體壓力方面，陰極入口操作壓力增至2 大氣壓，可有效的使燃料滲透進入觸媒層參與反應，使其電池性能有所提升；在溫度效應方面，333K 的電流密度值有最佳之效能輸出。加入一微孔層能夠有效減少甲醇水溶液穿透到陰極形成較大的過電位，使得在觸媒層的局部電流密度分佈較基本型為延伸。由模擬可知，微孔層能夠提升電池性能，且在甲醇穿透方面，能有效的減少穿透現象的發生。

關鍵字

微孔層；直接甲醇燃料電池；甲醇穿透；操作參數

並列摘要

ABSTRACT Direct methanol fuel cells (DMFCs) have significant potential to become a leading technology for energy conversion in a variety of applications. However, problems such as methanol crossover, reduce the efficiency of the cells. In this issue, a general 3D numerical computational fluid dynamics (CFD) model is established to simulate the effect of operating condition and that of a micro-porous plate on the direct methanol fuel cell performance. First, we choose the serpentine channels as the basic model. Compare the results on the different operating condition such as methanol feed concentration, temperature, anodic inlet velocity, and cathodic pressure. Second, in the anode, we add a micro porous plate between the collector and diffusion layer to know the effect of micro porous plate on the efficiency and methanol crossover. The results indicate that increasing in methanol feed concentration leads to increase the mass-transport and efficiency. The best methanol feed concentration is 2M. In the effect of the anodic inlet velocity, the model of V = 0.01m/ s is better than others on the diffusing reaction fuels. Increasing the cathodic pressure or increasing the temperature, it would be beneficial to permeate the reaction fuels into the catalyst layer. However, when the temperature is higher than 333K, the efficiency is reduced due to excessive methanol crossover. In the direct methanol fuel cell, the micro porous plate can reduce the over-potential which caused by methanol crossover, and furthermore that can extend the local current density of catalyst. In the simulation results, the micro porous plate authentically increases the performance of the cells, and the methanol crossover can be reduced significantly.

並列關鍵字

Direct methanol fuel cell ； Methanol crossover ； Operatin gcondition ； Micro porous plate

參考文獻

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國際替代計量

操作參數和微孔層對直接甲醇燃料電池性能之影響

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