摘要 本文為探討質子交換膜電池內陰極水生成量大小之排水問題，模擬三維之蛇行流道，在不考慮化學反應的條件下來觀察水在流道內的行為模式與入口空氣速度影響水排除效率的關係。 以三種不同之入口空氣速度利用水體積的多寡探討在少量水生成與大量水生成下水在流道內的行為模式。在流道中加入擋板與更改成局部漸縮式的流道並比較與原始流道的排水量的關係，並探討改變流道後影響排水量的因素。 本文結果顯示由於空氣對水的慣性力、黏滯力與剪應力帶動了水的運動。由於空氣速度分佈都會慢慢呈現fully developed的狀態，使水最後的分布均在流道兩側。少量水生成的情形由於本文只探討三個入口空氣速度的影響，所以若把速度加大後有多少水會帶離出口，並無法更確切得知。大量水生成時，速度較快的入口流速會導致較快的排水效率。改變流道會造成局部水在水通道變小處與角落處堆積，造成排水效率不良。 ABSTRACT This article discussed the water behavior in serpentine channel for proton exchange membrane fuel cell cathode and inlet velocity effect for water removing without considering chemical reaction. Using three different inlet velocities, this article discussed the water behavior in channel for less and larger water generation, and compared with the original model about the water removal by using partially blocked channel and gradually decreased area in part of channel. The factor of water removal in changing the fluid channel would be also discussed. This article pointed out that water would be moved by viscous force, inertia force, and shear stress which were provided by the air. Water would spread along two sides of channel because the air velocity would be fully developed gradually. For less water generation, this article only discussed three different inlet air velocity influences so that water removal by increasing air velocity was unknown. For larger water generation, with faster air inlet velocity, the water removal efficiency would be better. Changing the fluid channel made particle water accumulate in corner and in location of blocked channel which would cause the worse effect of water removal.