Investigation on the dispersion mass transfer in the interface between silicone oil and water. (October 2019)

• Record Type: Journal Article
• Authors: Li, Sheng; Yuan, Han; Zhang, Ji; Li, Yan; Zhang, Zhixiang; Yu, Shilong; Mei, Ning
• Is Part Of: International journal of heat and mass transfer. Volume 141(2019)
• Page Start: 222
• Page End: 232
• Publication Date: 2019-10
• Subjects: Dispersion mass transfer -- Associated matter -- Interface -- Oil-water mixture; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2019.06.018
• Languages: English
• ISSNs: 0017-9310

Abstract

Graphical abstract: Dispersion of silicone oil droplets and microstructure in silicone oil emulsion under freeze-scanning electron microscopy. Highlights: Cryo-scanning electron microscopy can be used to observe the oil/water interface. The associated matter exhibits a shell structure coated with dispersed droplets. The interface pressure reduction caused by dispersion is stronger than diffusion. The dispersion mass transfer includes droplet mixing and material dispersion. Abstract: In this work, the dispersion mass transfer of the silicone oil-water mixture, especially the material dispersion process in the silicone oil/water interface was studied. Adopt a combination of macro test methods and microscopic test methods, the Cryo-scanning electron Microscope (Cryo-SEM) and the Transmission Electron Microscope (TEM) were introduced into the work of this paper respectively. The interface region between the dispersed phase and the continuous phase in the silicone oil-water mixture was investigated by the Cryo-SEM, the boundary of pure silicone oil droplets was studied by the TEM. Moreover, a simple and practical silicone oil-water interface characteristic measuring instrument (ICMI) has been designed and made for the measurement of properties in the silicone oil-water mixture interface. The results show that the silicone oil boundary is continuous and free of other impurities, and the interface presents a three-layer structure of "silicone oil-associated matter-water", the Cryo-SEM images show the associated matter formed a layer of shell structure at the interface. The ICMI measurements show that the formation of the associated matter will lead to a rapid increase in interfacial pressure, while the associated matter migration will lead to rapid relaxation of the interface, and the relaxation effect is greater than the diffusion effect. This study shows that the dispersion mass transfer between silicone oil and water are consists of two interrelated stages: in the initial stage of mixing, continuous liquid phase splitting produces a large number of droplets, the diameter of the droplet group has a centralized distribution law, and there exists a sole clockwise circulation in the droplet. In the second stage, a kind of associated matter is formed by molecular aggregation in the interface area between the dispersed phase and the continuous phase, the associated matter contains both the silicone oil component and the water component. The formation and migration of the associated matter will result in a compression and relaxation effect of the interface. This manuscript provided a useful study for observing the oil/water interface with an electron microscope.