Behavioral characteristics of charged particle-laden droplets with the effect of non-uniform electric field

The regulation of particle-laden droplet behavior is crucial for interfacial heat and mass transfer in the liquid-liquid reaction systems. Accordingly, a clear understanding of droplet dynamic behaviors is of crucial importance. In this study, the behaviors of solid-particle-laden droplets in an immiscible dielectric liquid are experimentally investigated under the effect of a non-uniform AC electric field by high-speed imaging. The evolution processes of droplet formation, coalescence, dispersion as well as liquid bridge are analyzed systematically in variable applied voltages and particle concentrations. Results show that the droplet formation process are accelerated by increasing particle concentration, producing smaller droplets. When the applied voltage exceeds a certain threshold, the charged droplet coalescence occurs while the presence of particles would reduce this critical voltage. Cascade coalescence happens in the pure system with increasing voltage while the particle-laden droplets tend to coalesce individually. The droplet dispersion is found to dominate at high electric field strengths with its oscillation angle increased by particle concentration. Additionally, the liquid bridge expansion is reduced by the addition of particles, hindering the droplet coalescence. These findings provide insights into the regulation of particle-laden droplet behavior under the effect of electric fields.