Non‐coalescence behavior of neutral droplets suspended in oil under a direct current electric field

Abstract The excessive electric field gives rise to droplet non‐coalescence and droplet chains in the electric dehydrator, which severely deteriorates oil–water separation efficiency and even leads to short circuit. To reveal the underlying mechanism of droplet non‐coalescence, dynamic behavior of two neutral droplets in silicone oil under a direct current electric field is investigated by using high‐speed photography. The experimental results show that there exists a critical electric field strength above which two droplets will bounce off after the contact. The critical electric field strength of droplet non‐coalescence is affected by the initial separation distance between droplets, the radius of droplet, and the surfactant concentration. Whether the non‐coalescence behavior occurs in the electric field is determined by the competition of electric force and capillary force, which dominates the evolution of tiny connection channel.