Thermal Performance of Silicon Micro Heat-Sinks With Electrokinetically-Driven Flows

Abstract

A heat sink consisting of microchannels of rectangular or trapezoidal cross-section through which a polar fluid is circulated by means of an electro-osmotic pump was studied numerically. The equivalent pressure head–volume flow rate curve was determined for both geometries and the influence of the aspect ratio was investigated. The dimensionless temperature profile was determined keeping also the effect of Joule heating into account. The cross-sectional Nusselt number was calculated for the above conditions and was found to be strongly influenced by the ratio of Joule heating to convective heat flux, Mz. The dependence of the Nusselt number on the dimensionless electro-osmotic diameter (kDh) was also investigated for the two geometries and for increasing values of Mz, and a comparison with the values obtained analytically for slug flow under the same conditions was made. The value of the Nusselt number as a function of the aspect ratio was also calculated for increasing values of Mz. The numerical data presented in this paper can be useful to optimize the thermal performance of silicon micro heat-sinks.

Electroosmotically enhanced microchannel heat sinks

“…For the validation of the EOF scheme, the analytical solutions of Arulanandam and Li [10] are reproduced, as shown in Fig. 3, along with the numerical results obtained by Morini et al [13]. These numerical validations provide reasonable ground for the simulation of pressure-driven and electroosmotic convective flows.…”

“…(for the substrate conduction) (13) The formulated numerical model is set to solve for three-dimensional pressure-driven, electroosmotic, and mixed flows and conjugate heat transfer with the help of a commercial multiphysics solver CFD ACE+ [18].…”

“…Morini et al [13] numerically investigated the EOFs in the microchannel heat sinks of rectangular and trapezoidal cross-sections. They studied the effects of dimensionless electroosmotic diameter κDh and geometry aspect ratio on the cross sectional Nusselt number and suggested the application of electroosmotically-driven microchannel heat sink for a low heat flux removal rate.…”

Analysis and optimization of electrokinetic microchannel heat sink

“…The validation of the pure PDF has been reported in the previous study by Husain and Kim [6,8]. The further validation of pure PDF and pure EOF has been performed and the solutions are compared for the flow rate and Nusselt number with the analytical [4,17,18] and numerical [5] results as shown in Fig. 2.…”

“…Arulanandam and Li [4] characterized the flow on the basis of cross-section ion concentration and zeta potential using two-dimensional Poisson-Boltzmann and twodimensional momentum equations in the absence of significant Joule heating. Morini et al [5] investigated the effect of electroosmotic diameter and geometry aspect ratio on the cross-sectional Nusselt number for trapezoidal and rectangular microchannel heat sinks for a low heat removal rate. Although, the above studies have characterized thermal transport for EOF, very little attention has been given to three-dimensional numerical simulation of mixed EOF and pressure-driven flow (PDF) microchannel heat sink taking into account temperature dependent fluid properties and Joule heating effects.…”