Open Access

ARTICLE

Modeling of Electric Double Layer Effects through Pressure-driven Microchannel Flows

E.Y.K. Ng¹, S.T. Poh ²

1 College of Engineering, School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798.
2 R&D Engineer, MSC Group, Inc., Milling Systems & Concepts Ltd., 31 Gul Avenue, Singapore 629669.

Computer Modeling in Engineering & Sciences 2002, 3(3), 351-366. https://doi.org/10.3970/cmes.2002.003.351

Abstract

Advances in microfabrication technology have allowed the use of microchannels in ultra compact, very efficient heat exchangers, which capitalize on the channels large surface area to volume ratio, to transport high heat fluxes with small thermal resistances. One example is the cooling of microchips. However, research into microscale flow and heat transfer phenomena conducted by various researchers provided substantial experimental data and considerable evidence that the behaviour of fluid flow and heat transfer in microchannels without phase change may be different than that which normally occurs in larger more conventional sized channels.
This paper describes a numerical analysis with the use of a finite-volume scheme on the liquid flow and heat transfer in microchannels, with streaming potential as the driving force. The concept of electric double layer (EDL) was introduced to explain the microscale deviation. Governing equations were derived for fully developed rectangular microchannel flows. Towards a realistic modeling of the rectangular microchannels, a conjugate analysis, that solves both the solid and liquid regions, was performed. An additional source term resulting from the EDL effects was introduced in the conventional momentum equation, thereby modifying the flow and heat transfer characteristics. In this work, analyses concerning the effects of ionic concentration and zeta potential and channel dimensions were discussed.
The predicted results showed significant deviations in the velocity and temperature profiles under EDL effects. Friction factors and Nusselt numbers were calculated and compared for both EDL and non-EDL considerations. Stronger deviations were also observed as the aspect ratio decreases, suggesting the importance of EDL in microscale liquid flow.

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Keywords

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