質子交換膜燃料電池之流道模擬分析

Abstract

近年來石油耗竭以及環境污染的問題已被廣泛的討論，加上二氧化碳的排放逐年增加，全球暖化造成氣候異常的問題十分嚴重；人類爲永續生存，必須找尋一種乾淨無污染的新能源，然而質子交換膜燃料電池利用氫氣與氧氣透過觸媒無污染的產生電力，勢必在未來發電中佔有一席之地。 本研究是透過套裝軟體模擬質子交換膜燃料電池在不同流道及流道尺寸下，對於燃料電池之影響，並討論濃度場、壓力場、速度場、溫度場、電流密度以及功的改變。流道部份則選擇較常見的蜿蜒型流道及近來發現更有效率的指叉型流道作為改變流道尺寸的基礎，由於蜿蜒型流道之燃料電池是透過擴散效應將反應氣體傳輸至觸媒層發生反應；指叉型流道則是因為流道設計之特色，強迫反應氣體通過觸媒層，兩種流道氣體傳輸方式極為不同。流道尺寸方面，則是固定流道數目，改變流道之寬度、深度由0.3mm變化至1.0mm，並繪製燃料電池性能曲線（I-V Curve），藉此曲線判斷高電流密度下效率較佳的尺寸是否仍然能夠維持較高的電位，並分別找出蜿蜒型流道和指叉型流道的最佳化尺寸。

Recently the increasing energy price and the emission of greenhouse gases have become the major issues. A stack of fuel cells can produce electricity by converting hydrogen and oxygen into water, producing electricity in the process, which can be used to drive a motor to have a power work. The advantage of fuel cells is that they produce very little CO2, which causes global warming or nitrogen oxides that pollute the atmosphere. The PEMFC is one of them can convert hydrogen and oxygen into electric power without any pollution. The study is to simulate the performance of PEMFC in different flow field and flow channel size by the software. The suitable of flow channel in PEMFC is one of the major concerning design parameters. The serpentine flow channel was popular in the design of traditional flow fields. However, the interdigitated flow channel is found to be a more efficient way in recent years. The effects of the concentration, pressure, velocity, temperature, and current density profiles on the flow fields will be studied in details. The serpentine flow field and interdigitated flow field are chosen for this study due to their different fluid transportation mechanisms. The serpentine flow channel drives the fluid to generate chemical reaction by diffusion; on the other hand, the reactant gases are forced from flow channel and into catalyst layer by interdigitated flow channel. The performance of the flow channel design will be evaluated by current-voltage (I-V) curves in the range of 0.3mm to 1.0mm for the channel depth and width.