水-乙二醇基γ-Al_(2)O_(3)纳米流体的制备及其性能研究

Study on stability and thermal properties of water-ethylene glycol based γ-Al_(2)O_(3) nanofluids

以水-乙二醇为基液,通过两步法制备了质量分数为0.1%的γ-Al_(2)O_(3)纳米流体。考察了乙二醇体积分数、分散剂质量分数及种类、超声时间对纳米流体稳定性的影响。结果表明,乙二醇体积分数为35%时更适用于水-乙二醇基纳米流体的制备;质量分数为0.2%的阿拉伯树胶(GA)可有效提高γ-Al_(2)O_(3)纳米颗粒在水-乙二醇基液中的分散稳定性;超声30 min即可改善纳米流体的稳定性。最后评价了纳米流体的热物性,当与基液水浴加热到60℃时,水-乙二醇基γ-Al_(2)O_(3)纳米流体的导热性能提升幅度最大,为基液的1.35倍;在20~60℃加热过程中,Al_(2)O_(3)乙二醇基纳米流体黏度最低达0.97 mPa·s,所制备的纳米流体可适合用于流动换热。

Taking water-ethylene glycol as substrate solution, γ-Al_(2)O_(3)nanofluid with a mass fraction of 0.1% is prepared via a two-step method.The effects of ethylene glycol concentration, the type and concentration of dispersant, and sonication time on the stability of nanofluids are investigated by means of static sedimentation method, spectrophotometric method and particle size analysis.Experimental results show that ethylene glycol with a volume fraction of 35% is more suitable for the preparation of water-ethylene glycol based nanofluids.Gum arabic(GA) with a mass fraction of 0.2% can effectively improve the dispersion stability of γ-Al_(2)O_(3)nanoparticles in water-ethylene glycol substrate solution.And the stability of nanofluids can be improved by 30 min of sonication.Thermal properties of the nanofluid are evaluated.As the nanofluid is heated to 60℃ with the water bath of the substrate solution, its thermal conductivity is enhanced the most, which is 1.35 times that of the substrate solution.During the heating process from 20℃ to 60℃,the minimum viscosity of Al_(2)O_(3)glycol-based nanofluid is 0.97 mPa·s, suitable for flow heat transfer.