论文部分内容阅读
纳米流体的导热系数相对于基础流体而言有了显著提高,然而这种现象却无法用现有理论进行解释。应用平衡分子动力学方法对纳米流体的导热系数进行了模拟,并研究了纳米颗粒表面类似于固体的液体吸附层的存在和特性以及其对纳米流体导热能力的影响,在此基础上进一步对纳米流体导热性能显著提高的微观机理进行了探讨。模拟结果表明由于固体分子较强的吸引力,一部分液体分子被吸附在固体颗粒表面形成一个薄层,薄层内分子的排列结构不同于纯液体的分子排列结构,导热性能也优于基础流体,从而使得纳米流体的导热系数有了显著提高。最后对纳米颗粒表面液体薄层的厚度进行了定量计算。
The thermal conductivity of nanofluids has increased significantly relative to the base fluid, however, this phenomenon can not be explained by the existing theory. The thermal conductivity of nanofluids was simulated by the method of equilibrium molecular dynamics. The existence and characteristics of the liquid-adsorbed layer on the nanoparticle surface similar to the solid and its influence on the thermal conductivity of the nanofluid were also studied. On the basis of this, The microscopic mechanism of significantly improved thermal conductivity of fluids was discussed. The simulation results show that due to the strong attraction of solid molecules, a part of the liquid molecules are adsorbed on the surface of the solid particles to form a thin layer. The arrangement of the molecules in the thin layer is different from that of the pure liquid and the thermal conductivity is better than that of the basic fluid. So that the thermal conductivity of nanofluids has been significantly improved. Finally, the thickness of liquid thin layer on the surface of nanoparticles was calculated quantitatively.