Mondal, Sourav ; De, Sirshendu (2017) Pressure driven transport of neutral macro-solute in microchannel with porous wall at high surface potential International Journal of Heat and Mass Transfer, 104 . pp. 574-583. ISSN 0017-9310
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Official URL: http://doi.org/10.1016/j.ijheatmasstransfer.2016.0...
Related URL: http://dx.doi.org/10.1016/j.ijheatmasstransfer.2016.08.092
Abstract
Mass transport of macro-solutes under streaming potential in a microchannel with porous wall is presented in this study. The streaming field under high wall potential and overlapping electric double layer with coupled velocity and concentration of neutral solutes is computed numerically in this work. Streaming potential increases by 7 folds as kH decreases from 0.7 to 0.1 at ζ=-50mV, where, k−1 is Debye length, H is channel half height and ζ is wall zeta potential. Mass transport in terms of Sherwood number is calculated including osmotic effect of the solution and selective retention of macrosolutes. Electroviscous effects resulting from streaming potential and overlapping electric double layer at higher wall zeta potential have significant effect on velocity field and the mass transport of macrosolutes. Apparent viscosity due to this effect increases upto 3.2 times the solution viscosity at kH=0.2 for ζ=-50mV. This effect is intensified upto 4 times at higher wall potential,ζ=-200mV at kH=0.5. At these points, the velocity profile suffers the most adversely affecting the mass transfer reducing Sherwood number to 4 (about 5 times reduction compared to higher kH) at ζ=-200mV and kH=0.5. Sherwood number reduces by three to four folds at the critical kH values, representing the minimum. The induced electrical field due to the streaming potential is higher compared to axial pressure drop for ∣ζ∣>50mV at kH<0.3. The electric double layer overlaps for the values of kH upto 0.7 corresponding to ζ=-50mV. In case of high ζ(−200 mV), the centerline potential can be as high as 75% of the wall potential for kH)=1.5. The minimum wall Peclet number (Pew) occurs at kH)=1.5 for ζ=-200mV, which is five times less than the situation without electrokinetic effects.
Item Type: | Article |
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Source: | Copyright of this article belongs to Elsevier Science. |
ID Code: | 136258 |
Deposited On: | 21 May 2025 07:39 |
Last Modified: | 21 May 2025 07:39 |
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