Abstract:

Marangoni convection in the physical desorption of carbon dioxide from ethanol solvent was studied experimentally. Evolution of the convective structures on the free surface of liquid layers was captured through Schlieren method. Especially, its initial form was captured under appropriate procedures. Each structure changed from approximately round to polygon because of space restriction. Mechanism of the Marangoni convection in mass transfer process was deduced from the luminance distribution of Schlieren images. The emergence, development and fission of a single structure were analyzed qualitatively. Interfacial turbulence caused by the non-uniform mass transfer process led to the deformation of free interface. Finally, the entire surface was filled with polygonal structures with its shape fixed. Fading color in the Schlieren images can reflect the decrease of turbulent intensity during the desorption process, which can be attributed to the change of mass transfer driving force.

Key words: Marangoni convection, Schlieren, desorption, interface, mass transfer, convection structure

摘要：

通过纹影系统对乙醇溶液解吸CO₂的过程进行了实验研究，液层自由界面的俯视纹影图记录了对流结构的演化过程，并捕捉到了Marangoni对流结构的初始形态。相应的胞型结构因发展空间的限制，由初始的近圆形逐渐变成了多边形结构。利用纹影图片的灰度分布信息，对单个胞型结构的出现、发展及分裂阶段进行了定性分析,发现界面非均匀传质所引发的界面对流在其胞型发展的过程中将会导致界面的变形。湍动的后期，液层表面将布满多边形结构，且胞型结构基本保持不变。相应纹影图片的颜色差异随解吸的进行逐渐减小，即随着传质推动力的减小，湍动强度也将减弱。

关键词: Marangoni对流, 纹影, 解吸, 界面, 传质, 对流结构