Research Subject: The flow of two immiscible liquids has garnered significant interest over the past few decades due to its relevance in various industrial applications, including chemical, petrochemical, food, and other process industries. It is particularly encountered in the water-lubricated transport of high-viscosity oil through pipelines. One of the simplest methods for studying the mass transfer coefficient in a liquid–liquid system involves a single droplet rising through a second, stationary phase. While this approach is well understood for nearly spherical droplets without surface turbulence or oscillations, it remains complex for ellipsoidal droplets exhibiting oscillatory motion, particularly in systems characterized by low interfacial tension.
Research Approach: This study investigates the effect of mass transfer on the velocity and shape of droplets in a chemical system composed of normal butanol, succinic acid, and water. Several variables are explored, including the dispersed phase flow rate, droplet size, and succinic acid concentration within the dispersed phase. Experiments were carried out using the single-drop method in an extraction column, employing normal butanol droplets with diameters ranging from 0.3 mm to 1.3 mm and Reynolds numbers below 300.
Main Results: The results reveal that mass transfer significantly influences droplet velocity, delaying the attainment of terminal velocity. Despite deformation, the droplet regime remains unchanged. The low interfacial tension in the system leads to the formation of oval-shaped droplets, with aspect ratios decreasing to as low as 0.4. However, under mass transfer conditions, droplets become wider and more spherical, resulting in a 50% increase in aspect ratio at the highest succinic acid concentration and with the largest nozzle size, compared to conditions without mass transfer. Terminal velocity and droplet deformation were further analyzed using dimensionless numbers, including the Reynolds number, Eötvös number, and Weber number.
Article Type:
Original Research |
Subject:
mass-transport Received: 2024/06/10 | Accepted: 2025/01/1 | Published: 2024/06/25