在PEM燃料電池中，水管理一直是很困難的部分，特別是在一些孔質材料或是流道中，進入流道氣體中水蒸氣的分壓大於水的飽和蒸氣壓，或是電池的超做溫度低於水的沸點溫度，都會造成液態水在流道中形成。本研究以數值方模擬在流道中的移動性，並以商業軟體CFD-ACE+加以模擬，使用VOF模型追蹤水滴運動。另一方面，亦組裝一單蛇道電池模型，進行EIS實驗、IV曲線測試及可視化觀測，以確定凝結水對燃料電池性能的影響，並比較數值與實驗結果中水滴運動情形。
研究中，探討不同進口流速對水滴運動之影響，並考慮不同流道表面性質(如接觸角等)，對水滴運動所造成影響之探討。本研究在不同的電池操作條件下廣泛的討論液態水跟氣體在流道中的傳遞現象。以速度為2 m/s、重力方向為負Y方向和接觸角為70°為基本的比較範例，改變不同速度、接觸角和重力方向。結果顯示不同空氣速度和接觸角的確會明顯造成改變水滴移動，但重力方向的影響並不大。其中，尤以改變不同的接觸角所造成液態水滴運動型態的改變最為明顯。

Water management in a PEM fuel cell has been a critical challenging issue, especially in the porous electrodes and reactant flow channels. As the partial pressure of water vapor exceeds the saturation pressure of water or the operating temperature of a PEM fuel cell is lower than the dew point of water vapor, liquid water may form to occupy the pore of gas diffusion layer and block the gas transport path. Consequently, the limiting current density is lowered, resulted from the mass-transport-limitation. Therefore, this study presents a numerical investigation of air-water flow in single serpentine channel on the cathode of a PEM fuel cell by using the commercial computational fluid dynamics (CFD-ACE+). The volume of fluid (VOF) model is adopted to trace the shape if the water droplet. The dynamic behavior of the droplet is simulated in flow channel of fuel cell at different reactant flow velocities. In addition, the effect of surface properties of flow channel was examined under various hydrophilic/hydrophobic characteristics, such as the contact angle of droplet. In this study a single-cell PEMFC with a serpentine gas flow channel is made as the model for experiment. The base conditions are : The air velocity is fixed at 2 m/s; the gravity is in negative y direction; the contact angle is 70 degrees. Results show the contact angle is the most important factor for liquid droplet removal.

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