用光学干涉方法对液相扩散传质过程的研究

Study on mass transfer due to diffusion process with optical interferometry method

液相中扩散传质过程研究无论对于基础理论还是生产实践都具有重要的意义。但在通常的重力环境中,传质过程不是单因素地由浓度梯度来决定,对流和沉降会对实验研究产生重要的干扰。通过光学干涉技术的应用,实现对于扩散过程中的传质系数进行测量,实验中采用Mach-Zehnder干涉仪对于整个传质过程进行监控并记录相关图像信息。这些图像信息是贯穿在整个实验过程中的连续录像,不同于其它实验记录的静态图像。通过计算这些随时间改变的干涉条纹的变化,就可以推导出传质系数的结果。实验液体选用水/葡萄糖溶液,之后还将进一步将该实验装置搭载TF-1火箭,进行微重力实验,以排除重力产生的影响。

Mass transfer associated with diffusion occurs when the distribution of composition concentration in a solution is uneven, the net mass flux tends to decrease the magnitude of the concentration gradient. Nevertheless, the diffusion is not the unique factor to cause mass transfer, but also convection and sedimentation, in normal gravity. The mass transfer coefficient due to diffusion is an important parameter in both theoretical and practical aspects. However, it is difficult to accurately measure it in ground experiments because of the influence of convection and sedimentation caused by gravity. In this research, a specially designed two-wavelength Mach- Zehnder interferometer was used to monitor the whole mass transfer process in water/glucose mixture. A series of the evolution charts of mass distribution were recorded and then the relevant diffusion coefficient was determined. In addition,the experiment apparatus was set up for the TF-1 rocket, so the influence of gravity on the mass transfer can be demonstrated by comparing the results in microgravity environment after the rocket launching.