双电层效应对压力驱动微流体流动及传热的影响  

Electrical Double Layer Effect on Pressure-driven Liquid Flow and Heat Transfer in Microchannels

作　　者：谭德坤[1,2] 刘莹[1] 

机构地区：[1]南昌大学机电工程学院,南昌330031 [2]南昌工程学院信息学院,南昌330099

出　　处：《机械工程学报》2012年第18期144-151,共8页Journal of Mechanical Engineering

基　　金：国家自然科学基金重点资助项目(50730007)

摘　　要：在非对称壁面zeta电势及热通量边界条件下,研究双电层效应对平行微流道内压力驱动微流体流动及传热特性的影响。建立微流道内压力驱动流体的数学模型,双电层电势分布、流体流动及传热特性分别由Poisson-Boltzmann方程,修正的N-S方程,能量方程进行描述,对三个方程进行求解并得到微流道内电势,速度及温度分布的解析解。详细讨论动电参数、壁面zeta电势、上下壁面zeta电势比及热通量比等因素对电势场、流场、温度场及微流体传热性能的影响。结果表明,壁面zeta电势会影响微流道内电势分布,流动电势的改变会影响速度分布,进而影响微流道的温度分布与传热性能。在微尺度下,双电层效应对压力驱动流的影响很明显,与传统的无双电层效应的泊肃叶流相比,其流动及传热特性均有显著差异。The effect of the electrical double layer（EDL） on pressure-driven liquid flow and heat transfer in a flat microchannel are investigated under asymmetric boundary conditions including unequal zeta potentials and unequal heat fluxes on two walls.A mathematical model of pressure-driven liquid flow in microchannels is constructed.Electrical potential of EDL,liquid flow and thermal characteristics is determined using the Poisson-Boltzmann,the modified Navier-Stokes and the energy equations,respectively.The analytical solutions of the electrical potential,the velocity field and the temperature field are obtained by solving these three coupled equations.The influences of electrokinetic parameter（K）,zeta potential,ratio of two zeta potentials and heat flux ratio on electrical potential,velocity distributions,temperature distributions and heat transfer rate are discussed in detail.Results show that the wall zeta potential strongly affects the electrical potential distributions in microchannels,then the change of flow-induced streaming potential will affect the velocity profile,thereby affecting the temperature distributions and heat transfer.Therefore,EDL has a significant effect on electrokinetic flow in microchannels,compared with that in conventional Poiseuille flow without EDL effect,there is an apparent difference in the flow and heat transfer characteristics between them.

关 键 词：双电层 微流体 zeta电势 热通量 努赛尔数 

分 类 号：O363[理学—流体力学] TK124[理学—力学]