Enhanced Heat Transfer Through the Use of Nanofluids in Forced Convection

Much attention has been paid in recent years to the use of nanoparticle suspensions for enhanced heat transfer. The majority of this work has focused on the thermal conductivity of these nanofluids, which can be as much as 2.5 times higher than that of the plain base fluid. The present work moves beyond measurements of non-flowing liquids, to explore the role that nanofluids can play in enhancing convective heat transfer within microscale channels. A unique pseudo-turbulent flow regime is postulated, which simulates turbulent behavior at very low Reynolds numbers, in what are nominally laminar flows. The resulting fluid mixing has the potential to raise the average convective heat transfer coefficient within the channel. Numerical modeling, using the lattice Boltzmann method, confirms the existence of the pseudo-turbulent flow regime. Finally, experimental results are presented which demonstrate a significant heat transfer enhancement when using nanofluids in forced convection. The current results are especially relevant to microchannel heatsinks, where the low Reynolds numbers impose limitations on the maximum Nusselt number achievable.