Meng Min, Yang Qiang
School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China.
Computational Aerodynamics Institute, China Aerodynamics Research & Development Center, Mianyang 621000, P.R. China.
ACS Omega. 2023 Mar 22;8(13):11908-11915. doi: 10.1021/acsomega.2c07274. eCollection 2023 Apr 4.
Medium coalescence technology is a research hotspot for the separation of oil-in-water emulsions. However, the coalescence mechanism is still unclear, making it challenging to effectively improve the separation performance. Herein, the microscopic mechanism of medium coalescence was revealed. We found that the effective collision positions under the action of the flow field include the exposed granule surface, adherent droplet surface, and three-phase contact line. Furthermore, a numerical model of the microscopic process of water-in-oil emulsion permeation through a granular bed was established. The effects of different parameters (including the number of medium layers, Reynolds number, and inlet concentration) on the microscopic process of capturing dispersed-phase droplets in the bed and the pressure drop in the coalescence area were studied. The numerical results show that the droplets form the bridging structure between the granules. On the one hand, the bridging structure promotes the capture of the droplets by the bed; on the other hand, it causes pressure-drop fluctuations in the coalescence area and asymmetric distribution of the velocity field.
介质聚结技术是水包油乳液分离的研究热点。然而，其聚结机理仍不明确，这使得有效提高分离性能具有挑战性。在此，揭示了介质聚结的微观机理。我们发现，在流场作用下的有效碰撞位置包括颗粒暴露表面、附着液滴表面和三相接触线。此外，建立了油包水乳液通过颗粒床渗透微观过程的数值模型。研究了不同参数（包括介质层数、雷诺数和入口浓度）对床层中捕获分散相液滴微观过程以及聚结区域压降的影响。数值结果表明，液滴在颗粒之间形成桥接结构。一方面，桥接结构促进了床层对液滴的捕获；另一方面，它导致聚结区域的压降波动和速度场的不对称分布。
