光散射法同时测量气液二元体系的黏度、界面张力和热、质扩散系数的研究

Simultaneously Determination of Dynamic Viscosity,Interfacial Tension,Diffusivity of Binary Mixtures by Dynamic Light Scattering Method

当气液二元体系处于宏观热力学平衡状态时,表面与体相的波动弛豫时间具有不同量级,通过调节散射体积和改变采样时间,利用表面光散射实验系统可以同时探测到来自界面处表面波及体相中温度和浓度的波动信息。本文在已有的表面光散射实验系统上,以正庚烷与二氧化碳二元系统为例,同时实现了该体系黏度、界面张力和热、质扩散系数的测量,其扩展不确定度分布为3.0%,3.7%,20%,4.3%(k=2)。实验所得到的数据与文献进行了对比,其偏差在不确定度范围内,证明了本文提出的测量方法可以实现气液二元体系四种性质的同时测量,且测量精度可以满足一般工程应用。

When a vapor-liquid binary system reach macroscopic thermodynamic equilibrium,the fluctuations from interface and bulk can be distinguished due to their different time scales.By adjusting the scattering volume and the lag time of the correlator,surface fluctuations at the interface as well as the temperature and concentration fluctuations in the bulk of a binary mixture can be simultaneously obtained by surface light scattering.In this work,the dynamic viscosity,interfacial tension,thermal and mutual diffusivity of n-heptane and carbon dioxide system were simultaneously obtained on the traditional surface light scattering setup with an uncertainty of 3.0%,3.7%,20%,4.3%(k=2).The results were compared with the literature available,and the deviations were within the combined uncertainties.This work proves the four properties can be simultaneously determined with surface light scattering technic,and the accuracy can satisfy the demand of the industry use.