Effects of streamwise conduction on thermal performance of nanofluid flow in microchannel heat sinks

Abstract

Effects of streamwise conduction on the thermal performance of nanofluid flow in microchannel heat sinks under exponentially decaying wall heat flux are investigated. By employing the first-law principles, models with and without streamwise conduction term in the energy equation are developed for hydrodynamically fully-developed flow. Closed-form solutions are obtained and the analysis emphasizes on the details of discrepancy induced by streamwise conduction between the two models on the heat transport characteristics in nanofluids. The effects of the variations of Peclet number and nanoparticle volume fraction on the thermal characteristics of nanofluid flow in microchannel heat sinks are analyzed and discussed. Due to the tremendous increase in the effective thermal conductivity, the streamwise conduction effect is justified to be more significant in the nanofluid compared to its base fluid. The significance of the streamwise conduction which is prevalent in low-Peclet-number flow is greatly amplified when the volume fraction of nanoparticle is increased. At low Peclet number, the contribution of the streamwise conduction in nanofluid is found to be more than twofold of that in its base fluid. The effect of streamwise conduction on the nanofluid flow in microchannel heat sink is significant albeit not dominant particularly for low Peclet number and high nanoparticle volume fraction of the nanofluid.