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

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.