摘要
阳极催化层表面反应生成的CO2气体能否及时通过扩散层和阳极通道排出直接甲醇燃料电池(DMFC),对DMFC的性能及寿命具有重要影响,因此揭示气泡行为机理对DMFC的优化具有重要的意义。本文将DMFC阳极通道内气泡形成过程简化为气体垂直注入恒流液体中形成气泡的过程,利用可视化实验研究了气体垂直注入恒流液体中形成气泡以及气泡脱离的过程,考察了气体流量、液体流量以及浮力对气泡形成、生长及脱离过程的影响。结果表明:气泡的形成由气体的压力和表面张力产生的毛细压力共同作用,气泡生长和脱离过程相对于孕育过程较快;随着气体流量的增加,产生气泡的时间间隔变短,气泡间聚并的位置逐渐向前推移,气泡的脱离时间先减小后增大;随着液体流量的增加,气泡由弹状流向泡状流渐变,气泡的脱离时间先急剧变小,后趋于平缓;浮力对竖直向下形成气泡的影响较为明显,浮力的作用使竖直向下不易形成气泡且难于脱离孔道口。
The performance and lifetime of direct methanol fuel cell （DMFC） are great influenced by whether the CO2 produced from the catalyst layer can vent from the diffusion layer and the anode channel.Thus,the understanding for the mechanism of bubble behavior is essential for DMFC optimization.In the present study,the bubble behavior from the anode diffusion layer into the anode channel in DMFC was simplified as the process of bubble formation and detachment from cross-orifice in steady liquid flow,which was experimentally investigated by using a visual system.Effects of the gas/liquid flow flux and the buoyancy on bubble formation and detachment were investigated.Results showed that the bubble formation is dependent on the gas pressure and the capillary pressure produced by surface tension.Compared with the bubble gestating process,bubble formation and detachment are much quicker.With the gas flow flux increase,the time interval of bubble formation decreases,the bubble coalescence site moves forward,the detaching time decreases first and then increases.With the liquid flow flux increase,slug flow evolves to bubbly flow gradually,the detaching time decreases quickly first and then becomes constant.The buoyancy has a strong impact on the bubble formation in down direction.It is much more difficult for bubble to form and detach from the orifice in down direction,which contributes to the buoyancy effect.
出处
《化工进展》
EI
CAS
CSCD
北大核心
2010年第5期831-838,共8页
Chemical Industry and Engineering Progress
基金
浙江省自然科学基金资助项目(Y406163)
关键词
直接甲醇燃料电池
气泡
生长
脱离
聚并
影响因素
direct methanol fuel cells（DMFC）
bubble
formation
detachment
coalescence
effect factors
