光散射法流体迁移性质光学测量实验系统

Development of Light Scattering System for Transport Properties Measurement

基于光散射原理,研制了一套可以用于测量流体迁移性质的光学实验系统。该系统包含两路光路系统,分别是测量表面性质的表面光散射系统和测量体相性质的动态光散射系统。通过光路设计,可以实现两系统共用激光器、光子计数器、数字相关器等重要设备以及高压实验样品池。实验系统压力测试范围为0~10 MPa,温度测试范围为283 K^400 K,温度波动度小于±1 m K/h。采用光频外差的方法提取液体分子波动信息,并通过数值求解色散方程获得液体的迁移性质。利用参考物质正庚烷和R134a检验了实验系统,获得的表面张力、黏度、热扩散系数、定压比热容值与文献值的偏差分别为2.29%、0.57%,0.12%,0.06%。通过不确定度分析,搭建的系统测量表面张力、黏度、热扩散系数、定压比热容值的不确定度分别为1%、2%、2%、4.6%(k=2)。

Based on the light scattering theory, a new apparatus for transport properties measurement is built. The apparatus consists of two systems which are surface light scattering system and dynamic light scattering system, for measuring the surface and bulk properties of liquid, respectively. By a proper optical design, the two system can share the key devices, including the laser, single photon detector and digital correlator, and also the high pressure vessel. The whole system is designed and allowed to work at the pressure of 0~10 MPa and the temperatures between 283 K and 400 K with a stability better than ±1 mK/h. Since the frequencies of capillary waves are much smaller than that of laser light, optical mixing technique and heterodyne scheme are used to extract physical information. For checking the accuracy and reliability of the system, liquid surface tension, viscosity of heptane, thermal diffusion coefficient and specific heat capacity of R134a are measured. The deviations between experimental values and reference data are 2.29%, 0.57%, 0.12%, 0.06%, respectively. The total uncertainty for the measurement of surface tension, viscosity, thermal diffusion coefficient and specific heat capacity are estimated to be 1%, 2%, 2%, 4.6% （k=2）, respectively.