PARAMETRIC STUDIES OF MICROCHANNEL CONJUGATE LIQUID FLOWS WITH ZETA POTENTIAL EFFECTS

Abstract

This paper presents a computer model 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. Interfacial electrokinetic phenomena such as the EDL play important roles in various transport processes in microchannels. Conventional theories of fluid mechanics and heat transfer cannot explain these phenomena observed in microchannels. The presence of the EDL reduces the liquid velocity within the microchannel, which affects the heat transfer mechanism in the pressure-driven microchannels. In this paper, a source term in the form of the electrical body force was included in the governing momentum equations for microscale computation with the effects of the heat transfer through the channel wall. The numerical parametric studies performed allowed the conclusion that the flow and heat transfer characteristics in microchannels depend on the bulk ionic concentration, the Zeta potential and the aspect ratio of the channel, which is the reflection of the EDL effects. The existing of the EDL is more significant as aspect ratios decrease. Also, the friction coefficient increases as the ionic concentration of the aqueous KCL solution decreases and the Zeta potential of the system increases. However, one should be aware that the ionic concentration of 10-8 M is unlikely in reality.