Study On Flow And Heat Dissipation Performance Of Water-based Alumina Nanofluids In Microchannels

As the number of transistors integrated in a unit area on a chip increases exponentially,conventional cooling methods can no longer meet the heat dissipation requirements of high-power chip devices,so the search for efficient heat dissipation devices and heat dissipation media has become the focus of development in the industry.Microchannels have the advantages of small occupied space,high heat dissipation efficiency and integrated processing with chips,while the new heat-exchange nano-fluid has good heat exchange effect.Therefore,the combination of nanofluids and microchannel technology is a good way to solve the new thermal management of high heat flux and high integrated chip devices.In this paper,serpentine microchannel is combined with water-based alumina nano-fluid,and its flow and heat dissipation properties are studied.The stability of nanofluids is the basis of subsequent research.Firstly,the influence of nanoparticles and dispersant sodium dodecyl benzene sulfonate(SDBS)on the stability of nanofluids is analyzed by transmittance method.Based on response surface analysis method,the central composite experimental design method is adopted for the main factors affecting the stability of nanofluids.The significant influence of various factors on the stability of nanofluids is as follows: volume fraction of nanoparticles >mass fraction of > SDBS > stirring time > ultrasonic time.The significant effects of interaction on the stability of nanofluids are as follows: volume fraction of nanoparticles and stirring time > stirring time and ultrasonic time > SDBS mass fraction and ultrasonic time > volume fraction of nanoparticles and sdbs mass fraction > sdbs mass fraction and stirring time > volume fraction of nanoparticles and ultrasonic time.Secondly,the research on water-based alumina nano-fluid flow heat dissipation experiment is carried out,which is mainly divided into two parts: 1.A nano-fluid flow heat dissipation experiment platform is built,which is mainly composed of three parts:micro-channel heat dissipation system,data acquisition system and heat source system.Serpentine micro-channel and tightening micro-channel positioning fixture are mainly designed,and a graphical interface is developed for the data acquisition instrument through Labview.The thermal balance of the experimental platform is calculated with a deviation of less than 5%,which proves that the experimental platform has good reliability and can meet the accuracy of subsequent experimental data.2.Based on the experimental platform,the flow heat dissipation of nano-fluid with volume fraction of0.1%-0.5% was studied,and the experimental results of flow heat dissipation ofnano-fluid were analyzed.The results are as follows:(1)According to the heat transfer characteristics,the wall temperature of nano-fluid is 2 ? lower than the highest wall temperature of deionized water,and the Nusselt number of nano-fluid is 1.12-1.66 times of deionized water,indicating that the heat transfer enhancement effect of water-based alumina nano-fluid is remarkable;(2)In terms of fluidity,the flow resistance of nano-fluid in the experiment is 1.02 to 1.80 times that of deionized water.This indicates that the water-based alumina nano-fluid has the disadvantage of increasing power consumption.(3)From the comprehensive performance point of view: all the nanofluids used in the experiment have enhanced heat transfer factors greater than 1,and the enhanced heat transfer effect is better than that of deionized water.The nanofluids with volume fraction of 0.4% have an average enhanced heat transfer factor of 1.4,which is the best comprehensive performance.Finally,based on the above experiments,the serpentine microchannel structure is simulated and analyzed with 0.4% volume fraction of nano-fluid as cooling medium.It is found that with the increase of channel spacing,the temperature on the chip surface increases and the pressure drop decreases.According to the structural optimization analysis of serpentine microchannel,when the channel spacing is 4mm,the microchannel has the best flow heat dissipation performance.