Numerical simulation of mixing enhancement in T-shaped micromixers
-
摘要: 为了研究不同混合强化方式对微混合的影响,采用有限元法对T型微混合器内增加壁面非均匀Zeta电势的主动式混合以及嵌入肋板的被动式混合进行了数值模拟.对比分析了3种T型微混合器内流场、速度场和浓度场的分布,并研究了不同T型微混合器内溶液混合效率与Re和Sc之间的关系.研究结果表明,两种溶液的混合效率随着Re和Sc的增加非线性减小,且减小趋势变缓;嵌入肋板的被动式T型微混合器内的混合效率沿水平微通道方向上存在较大的波动;增加壁面非均匀Zeta电势的主动式T型微混合器内的混合效率沿水平微通道方向上的波动较小,且这种波动在高Re或低Sc时会被抑制.Re对混合方式的强化效果也有很大的影响.当Re较小时,增加壁面非均匀Zeta电势的主动式混合能更好地提高溶液的混合效率,但当Re较大时,嵌入肋板的被动式混合的混合效果更好.Abstract: To study the effects of different mixing enhancement modes on micromixing, numerical simulations with the finite element method were carried out on the simple T-shaped micromixers, the active T-shaped micromixers with surface heterogeneous Zeta potential and the passive T-shaped micromixers with embedded ribs. The flow fields, velocity fields and concentration fields in the 3 kinds of T-shaped micromixers, as well as the relationships between the mixing efficiency and 2 dimensionless parameters Re and Sc, were investigated. The results show that the mixing efficiency decreases with Sc and Re, fast at first and then slowly. The mixing efficiency in the passive T-shaped micromixer with embedded ribs has large undulation along the microchannel, while that in the active T-shaped micromixer with surface heterogeneous Zeta potential has only gentle undulation, and this undulation will be restrained in the cases of high Re values or low Sc values. The Re value also notably influences the improving effect of different mixing enhancement modes. For relatively lower Re values, the outlet mixing efficiency is improved more evidently in the active mixing enhancement mode with surface heterogeneous Zeta potential; otherwise, for relatively higher Re values, that happens instead in the passive mixing enhancement mode with embedded ribs.
-
Key words:
- T-shaped micromixer /
- mixing enhancement /
- electroosmotic flow /
- mixing efficiency
-
[1] Wong S H, Ward M C L, Wharton C W. Micro T-mixer as a rapid mixing micromixer[J]. Sensors and Actuators B: Chemical,2004,100(3): 359-379. [2] Nguyen N T, Wu Z. Micromixers—a review[J]. Journal of Micromechanics and Microengineering,2005,15(2): R1-R16. [3] Wong S H, Bryant P, Ward M, Wharton C. Investigation of mixing in a cross-shaped micromixer with static mixing elements for reaction kinetics studies[J]. Sensors and Actuators B: Chemical,2003,95(1/3): 414-424. [4] Mouza A A, Patsa C M, Schnfeld F. Mixing performance of a chaotic micro-mixer[J]. Chemical Engineering Research and Design,2008,86(10): 1128-1134. [5] 王昆, 王嘉骏, 冯连芳, 顾雪萍. 内置阻块型微混合器内流体混合强化的数值模拟[J]. 化学工程2010,38(12): 30-34.(WANG Kun, WANG Jia-jun, FENG Lian-fang, GU Xue-ping. Numerical simulation of fluid mixing reinforcement in micro-mixers with barriers embedded[J]. Chemical Engineering(China),2010,38(12): 30-34.(in Chinese)) [6] Mouheb N A, Malsch D, Montillet A, Solliec C, Henkel T. Numerical and experimental investigations of mixing in T-shaped and cross-shaped micromixers[J]. Chemical Engineering Science,2012,68(1): 278-289. [7] Parsa M K, Hormozi F, Jafari D. Mixing enhancement in a passive micromixer with convergent-divergent sinusoidal microchannels and different ratio of amplitude to wave length[J].Computers & Fluids,2014,105: 82-90. [8] 杨大勇, 王阳. 微通道中电渗流及微混合的离子浓度效应[J]. 应用数学和力学, 2015,36(9): 981-989.(YANG Da-yong, WANG Yang. Effects of ion concentration on electroosmotic flow and micromixing in microchannels[J]. Applied Mathematics and Mechanics,2015,36(9): 981-989.(in Chinese)) [9] 李战华, 吴健康, 胡国庆, 胡国辉. 微流控芯片中的流体流动[M]. 北京: 科学出版社, 2012: 53-57. (LI Zhan-hua, WU Jian-kang, HU Guo-qing, HU Guo-hui. Fluid Flow in Microfluidic Chips [M]. Beijing: Science Press, 2012: 53-57.(in Chinese)) [10] Cho C C, Ho C J, Chen C K. Enhanced micromixing of electroosmotic flows using aperiodic time-varying zeta potentials[J]. Chemical Engineering Journal,2010,163(3): 180-187. [11] 唐桂华, 王斐斐, 毕成, 陶文铨. 微尺度电渗混合强化的数值研究[J]. 工程热物理学报, 2010,31(10): 1721-1723.(TANG Gui-hua, WANG Fei-fei, BI Cheng, TAO Wen-quan. Numerical study of electroosmotic mixing enhancement[J]. Journal of Engineering Thermophysics,2010,31(10): 1721-1723.(in Chinese)) [12] Jeong S, Park J, Kim J M, Park S. Microfluidic mixing using periodically induced secondary potential in electroosmotic flow[J]. Journal of Electrostatics,2011,69(5): 429-434. [13] Lin T Y, Chen C L. Analysis of electroosmotic flow with periodic electric and pressure fields via the lattice Poisson-Boltzmann method[J]. Applied Mathematical Modelling,2013,37(5): 2816-2829. [14] Alizadeh A, Zhang L, Wang M. Mixing enhancement of low-Reynolds electro-osmotic flows in microchannels with temperature-patterned walls[J]. Journal of Colloid and Interface Science,2014,431: 50-63. [15] Ebrahimi S, Hasanzadeh-Barforoushi A, Nejat A, Kowsary F. Numerical study of mixing and heat transfer in mixed electroosmotic/pressure driven flow through T-shaped microchannels[J]. International Journal of Heat and Mass Transfer,2014,75: 565-580. [16] Kandlikar S, Garimella S, Li D, Colin S, King M R. Heat Transfer and Fluid Flow in Minichannels and Microchannels [M]. Elsevier, 2005. [17] Erickson D, Li D. Influence of surface heterogeneity on electrokinetically driven microfluidic mixing[J]. Langmuir,2002,18(5): 1883-1892. [18] Zhao C, Yang C. An exact solution for electroosmosis of non-Newtonian fluids in microchannels[J].Journal of Non-Newtonian Fluid Mechanics,2011,166(17): 1076-1079.
点击查看大图
计量
- 文章访问数: 950
- HTML全文浏览量: 91
- PDF下载量: 625
- 被引次数: 0