Analysis of heat transfer performance and energy efficiency of the microchannel combined with ultrasound waves and nanofluid

Abstract

The ultrasonic and nanofluid are widely adopted to enhance the heat transfer performance of the microchannel heat sink. However, the incorporation of a high mass fraction of nanofluid would worsen the flow resistance and heat transfer characteristics due to the phenomenon of agglomeration and sedimentation of nanoparticles. To address this issue, the ultrasound waves are used in the liquid cooling loop with the nanofluid serving as the working medium. Furthermore, the combined effect of the ultrasonic and nanofluid on the enhanced mechanism is experimentally investigated. The results indicate that the ultrasonic waves would trigger the ultrasonic cavitation and acoustic streaming effects within the nanofluid, which consequently disturbs the thermal boundary layer and achieves a maximum 19.9 % enhancement of heat transfer efficiency in the microchannel heat sink. In addition, the motion of the nanoparticles is enhanced by ultrasonic waves, which facilitates a reduction of 5.6% and 10% in the friction coefficient and pressure drop, respectively. Moreover, with the mass fraction of 0.08 wt% nanofluid, the microchannel heat sink could reach the optimized enhancement effect in heat transfer performance assisted with the ultrasonic, resulting in a 40.4% increase in heat transfer coefficient. This work also analyzes the energy efficiency of the combined nanofluid and ultrasonic. It can be found that ultrasonic waves could expand the application concentration range for nanofluid in microchannel heat exchangers.