Abstract: The performance of passive direct methanol fuel cell can be greatly influenced by the removal of the carbon dioxide produced from catalyst layer diffusion layer and the anode channel. The study of gas-liquid two-phase flow behavior taking place in the anode channel is necessary for the optimization of the passive direct methanol fuel cell. A volume of fluid model was used to simulate the formation of bubbles in the rest methanol solution under various conditions. Experiments of visualization were conducted to validate the results. The results showed that portrait of bubble was elongated with buoyancy and surface tension，bubble tail was cut under the sheer force of liquid. The inclination angle may get bubble detachment more easily. Bubbles were able to merge with gas rate increasing. Bubbles detachment could form a chain in high methyl concentration solution. The results help to design and optimize the diffusion layer.

Key words: passive direct methanol fuel cell, diffusion layer of gas, computational fluid dynamics

摘要： 在被动式直接甲醇燃料电池（DMFC）中，阳极催化层表面电化学反应生成的二氧化碳（CO2）通过扩散层及时排出阳极通道，对提高直接甲醇燃料电池的性能具有重要意义，因此研究阳极通道内的气液两相流对电池性能的优化具有非常重要的意义。利用计算流体力学模拟软件Fluent，采用VOF（volume of fluid）两相流模型追踪气液界面的方法对静止甲醇溶液中CO2气泡形成的过程进行模拟，利用可视化实验对部分结果进行验证，结果表明：气泡在浮力和表面张力作用下被拉长，受尾部液体剪切力作用脱离，倾斜的扩散层表面有利于气泡尽快的离开孔口，气速较大时气泡在脱离前会出现多次融合，气泡在高浓度甲醇溶液中以气泡链的方式产生。研究结果为扩散层的制备和优化提供了参考。

关键词: 被动式直接甲醇燃料电池, 气体扩散层, 计算流体力学