Work

Regime map of non-coalescence between two equal-sized uncharged water droplets suspended in oil: A numerical study

Year: 2024

Type: article

Abstract: Electrostatic demulsification is based on electrocoalescence when conducting droplets of the dispersed phase merge under the action of a high electric field. However, different non-coalescence outcomes are realized instead of coalescence if a certain field strength is exceeded. These outcomes might affect demulsification negatively to varying degrees. To design electrostatic coalescers and determine effective modes, it is important to understand which modes are possible and in which cases they are implemented. This paper is devoted to numerical simulation of collision and consequent separation of conductive same-sized droplets of different sizes (from 0.3 to 2 mm) under the effect of a constant voltage exceeding the threshold of the transition from coalescence to non-coalescence. The computations were based on the arbitrary Lagrangian-Eulerian method. Four possible modes were identified: rebound, separation into three or multiple drops, and electrospraying. A “regime map”—a diagram of possible outcomes depending on the size of drops and the electric field strength—was formed and analyzed in order to summarize the results and identify the most favorable modes of operation of coalescers. The map revealed an area when coalescence is substituted with only rebound when drop radius increases, i.e., when there will be no smaller drops after the interaction.

Source: Physics of Fluids

DOI: 10.1063/5.0240476

Authors: D. D. Saifullin, D. S. Lukin, A. V. Samusenko, V. A. Chirkov

Institution: St Petersburg University

Language: English

Topic: Electrohydrodynamics and Fluid Dynamics

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: green

Funder: Russian Science Foundation

Award: G1723024456