Al_2O_3-H_2O纳米流体布朗运动实验研究

The Research on the Brownian motion of Al_2O_3-H_2O Nanofluids

使用VIC-2D、m ATLAB、Linksys32、Image-Pro Plus和Origin8.5等软件,以Al_2O_3-H_2O纳米流体为实验材料,分析降温过程中粒径(50、100、500nm)和浓度(0.01%、0.05%、0.1%)不同时其内部颗粒的布朗运动并验证其随机性,总结降温过程中单个Al_2O_3-H_2O纳米颗粒团聚体的运动轨迹、速度以及Al_2O_3-H_2O纳米颗粒团聚体的表面积、直径随时间和温度的变化关系。结果表明:显微镜整个视野范围内纳米流体的平均、最大直径和平均、最大面积分别随时间、温度的变化近似服从正弦分布;降温速率相同时,不同粒径和质量分数的Al_2O_3-H_2O纳米流体呈现最佳分散性的时刻与温度各不相同。该实验结果为后人探究完善纳米流体的布朗运动提供了一定的参考数据和理论依据,甚至对全面系统地表征纳米流体的微观结构、建立其热物理参数和热学特性测试的标准化仪器、规范和测试条件也是必要的。

With the help of VIC-2D,m ATLAB,Linksys32,Image-Pro Plus and Origin8. 5 named software,we carried out experiments on the nanoparticles motion in Al_2O_3-H_2O nanofluids of different particle sizes（ 50,100,500） and different mass fraction（ 0. 01% 、0. 05% 、0. 1%） to analyze its Brownian motion and verify its stochastic in the temperature reducing process. And the changes of the trajectories and velocities of single nanoparticles aggregate and the surface and diameters of the nanoparticles aggregates with time and temperature are summarized during the process of cooling. The results show that,firstly,the variation of the diameter and surface of the nanoparticles in the whole field of the visual of the microscope is approximately subject to the sine distribution. secondly,when the cooling rate is same,the moments and temperature of the best dispersion of Al_2O_3-H_2O nanofluids are found to be different with the mass fraction or the particle sizes changing. The results can provide a theoretical basis for later experiments and analysis on researching and improving the Brownian motion of nanofluids,even it is of great necessity for expressing systematically the micro-structure of nanofluids,and establishing its thermal physical parameters, and standard instruments,specifications and test conditions for thermal characterization testing.