Influence of ceramic based nanofluids and inlet header geometry on the thermal performance of wavy microchannel heat sink

Abstract

The increasing need for development in microelectronics and systems has naturally led to pursuit of modern advancementsin the field of cooling technology. Microchannels offer excellent high temperature heat management in electronic systems. Microchannels utilize fluids capable of transferring heat energy released by the operating circuits by fluid flow. The fluid flowand nature of fluid are highly resonant on the performance of the microchannel heat sinks. The present work is a novelapproach of an investigation of three-dimensional ceramic based nanofluids flow performance in a fabricated wavymicrochannel heat sink with varying inlet header geometry. The coolant nanofluids investigated are concentrated with silicondioxide (SiO2) and aluminum oxide (Al2O3) ceramic nanoparticles with varying volume percentages and their hydraulic andthermal performance were investigated. Experimental evaluations were performed to determine variations in local Nusseltnumber and axial coefficient of heat transfer for SiO2 and Al2O3 nanoparticles concentration. Computational fluid analysis wasperformed to evaluate transport equations to determine pressure drop, friction factor and Nusselt number of the fluid flow. It was observed that increasing heat flux amplitude causes rise of local maxima of Nusselt number with corresponding decreaseof the local minima. The decrease of local minima was more profound than increase of local maxima. The different inlet headergeometries influence the local Nusselt number with conical frustum header producing the value followed by semi-circular,rectangular and triangular inlet section geometries. The observed Nusselt number and heat transfer rate was highest in caseof Al2O3 followed by SiO2 and distilled water as coolant fluids for the heat sink. Higher Nusselt number was observed forconical frustum and semi-circular inlet header geometries when SiO2 and Al2O3 based coolant fluids were used. High frictionfactor was observed when the nanoparticle concentration was 0.25 volume percentage for the entire Reynolds number underinvestigation. A computational model was utilized to evaluate the drops in pressure in the wavy microchannel and determinefrictional characteristics of the nanofluids in the present work.