近临界区表面光散射法乙醇界面性质的实验研究

Experimental Investigation of Interfacial Properties of Ethanol Near the Critical Point by Surface Light Scattering Method

针对高温及近临界区流体界面性质测量难题,本文研究了表面光散射法在该温度区间流体表面张力和黏度的高精度测量方法。获取了饱和状态下乙醇在温度范围为303 K∼T_(c)内的表面张力和黏度,并利用实验数据分别拟合了对应的van der Waals方程和含临界项的温度倒数多项式方程,在全温度范围内实验值与方程的偏差均在1.5%之内。同时分析了表面光散射法测量流体表面张力和黏度的测量扩展不确定度,当对比温度T_(r)=T/T_(c)<0.9时,表面张力和黏度的测量不确定度分别为1%和2%(k=2);当对比温度0.90<T_(r)<0.99时,测量不确定度范围分别为1%∼7%和2%∼3%(k=2)。

The present work investigated the liquid surface tension and kinematic viscosity of ethanol under saturation over a wide temperature range from 303 K to the critical temperature.With the obtained data,the liquid surface tension and viscosity were correlated as the van der Waals and polynomial equations of temperature with an additional term to capture the tendency of the properties close to the critical point and the deviations of both properties from the fitted equations were within 1.5%over the entire temperature range.The uncertainties for measuring the surface tension and viscosity by surface light scattering were estimated to be 1%and 2%(k=2),respectively,at the reduced temperature(T_(r)=T/T_(c))below 0.9.For the reduced temperature in the range between 0.90 and 0.99,the uncertainties of 1%∼7%and 2%∼3%(k=2),respectively,were estimated for the two properties.