纳米流体黏度和流变特性的试验研究

Experimental Study of Viscosity and Rheological Properties of Nanofluids

对纳米流体黏度和流变特性的研究有助于揭示纳米流体强化传热和传质过程的机理。选用无水乙醇为基液,应用两步法制备了稳定性良好的纳米流体,采用CPE40锥板式黏度计测量了不同纳米粒子、体积份额、粒子粒径和温度下的纳米流体的黏度,分析了黏度随这些因素的变化规律。结果表明,纳米流体黏度随纳米粒子体积份额的增加而增大,随纳米粒子粒径的增大而减小,随温度的增加而降低,且这些因素对不同纳米流体黏度的影响不同。此外,还用Brookfield DVⅢ+LVDV-E流变仪测量了不同纳米流体的流变曲线,结果表明,在所配制的体积份额内,各纳米流体的黏度不随剪切速率的变化而变化,为典型的牛顿型流体。

The research of viscosity and rheological properties will help reveal the mechanisms on the heat and mass transfer of nanofluids.Nanofluids were prepared using a two-step method with the ethanol as the base fluid,the viscosity was measured using the CPE40 cone-plate viscometer under different kinds of nanoparticles,different volume fraction,different particle size and temperature conditions.The effect of these factors on the viscosity of nanofluids was also analyzed accordingly.The results indicate that the viscosity of nanofluids increases with increasing particle concentration,and decreases with increasing particle size and temperature.However,the effect of various factors on the viscosity of the nanofluids with different nanoparticles is different.In addition,the rheological properties of these nanofluids were also measured by using Brookfield DVⅢ＋LVDV-E rheometer.The results also demonstrated that these nanofluids were Newtonian fluids.