基于Fluent的液体进料DMFC阳极两相流数值分析

Numerical Analysis of Two-phase Flow of DMFC Anode Based on Fluent

生成物CO_2能否及时排除流道和甲醇溶液能否更有效的传输到扩散层对液体进料的直接甲醇燃料电池性能有着重要影响.Volume of Fluid(VOF)可以用来研究平行流道孔逸出CO_2气体的演变,包括气泡的生长、变形、脱离及运动规律.通过建立流道的三维模型,研究了湿润性对流道中气泡演变的影响.通过软件FLUENT进行模拟,模拟分析了亲水性(35°)、中性(90°)、弱疏水性(115°)、强疏水性(125°)情况的扩散层壁面,结果表明:气泡是由两相流的压力差和表面张力共同作用形成的,弱疏水性的扩散层表面有利于气泡脱离及气泡聚合的过程.弱疏水性的扩散层表面相对于亲水性的壁面,气泡排出的更稳定;弱疏水性的扩散层表面相对于强疏水性壁面,气泡脱离体积更小,脱离的时间更短.

Exhausting CO2 in time and effective transferring of methanol solution to the diffusion layer have important influence on the performance of the liquid feed direct methanol fuel cell (direct methanol fuel cell, DMFC).VOF has been used to study the evolution of CO2 gas which leaked from the parallel channel, including growth,deformation,detachment and motion of the bubble.A three-dimensional model of channel has been established to study the effect of wettability on bubble evolution in channel.The software FLUENT was used to simulate and analyze the diffusion layer wall surface of hydrophilic (35°),neutral (90°),weak hydrophobic (115°)and strong hydrophobic (125°).The analysis results show that the bubble is jointly by the pressure difference between the two phases,and surface tension effect as well.The surface of the weak hydrophobic diffusion layer is conducive to the process of bubble separation and bubble coalescence,that is,it showed bubble discharging is more stable compared with the hydrophilic surface,while smaller bubble volume and shorter escaping time compared with the strong hydrophobic surface.