Electric Field Driven Separation of Oil-Water Mixtures: Model Development and Experimental Verification

Abstract

Electrocoalescence of aqueous droplets in oil emulsions is commonly contemplated for enhancing separation. High voltage electric fields can induce charges to drops evoking merging of adjacent droplets. The newly formed larger drops then sink faster in gravitational common settlers. Therefore, separation performance of an electrostatic coalescer is strictly linked to characteristics of the electric field and properties of the liquid-liquid system. In this work, the coalescence performance of water droplets sinking in dodecane at a pulsed DC electric field is investigated. An experimental setup allowing the simultaneous injection of similar sized drops, setting of voltage and pulsation frequency, and particle tracking at high frame rate and resolution is designed. The generated data are used to check the validity of modeling approaches for drag, dipole-dipole forces, and film-thinning. Furthermore, CFD simulations are carried out using a volume of fluid method tracking the interfaces between the two phases.