Electrocoalescence of water droplets in an insulating liquid

Abstract The basic processes leading to coalescence of small droplets of conducting water dispersed in an insulating liquid are examined in the case of an emulsion flowing between two coaxial cylindrical electrodes and subjected to an electric field. The formula giving the interaction force between two droplets and the equation governing the evolution of a polydispersed emulsion are first recalled. Expressions are derived for the coalescence rate when retaining only the field induced interaction between droplets and the characteristic coalescence time is estimated. Finally it is proposed that the shear rate plays the major role in bringing the droplets into contact.