COMPUTATION OF THREE-DIMENSIONAL DEVELOPING PRESSURE-DRIVEN LIQUID FLOW IN A MICROCHANNEL WITH EDL EFFECT

Abstract

Advances in miniature fabrication technology have allowed the possibilities of using microchannels in ultracompact, very efficient heat exchangers, which capitalize on the large surface area-to-volume ratio of the channels, to transport high heat fluxes with small thermal resistance. This article describes a developing flow model by using 3-D Navier-stoke equations with flow pressure as a driving force to simulate the developing liquid flow phenomenon in microchannels. The concept of electric double layer (EDL) is introduced to explain the microscale deviation between flow in microscale channels and large-scale channels. Governing equations are stated for developing rectangular microchannel flows. An additional source term, related to the electric potential and resulting from the EDL effect, is introduced in the conventional momentum equation as a body force, thereby modifying the flow and heat transfer characteristics. The electric potential distribution is simulated using a Poisson-Boltzmann equation. A finite-volume scheme is used to solve the differential equations. Results comparing the performance of the microchannel under different factors such as Reynolds number, nondimensionalized electric potential, etc., are shown and discussed. Nusselt numbers for each case, with or without EDL effect, are also included, so that the actual effectiveness of the microchannel can be understood.