Droplet dynamic response in low-viscosity fluid under a pulsed direct-current (DC) electric field and a sinusoidal electric field is investigated by experiments and numerical simulations. The coupled level set and volume of fluid method is employed to capture moving interface and the numerical method is validated by experimental results. This article focuses on the effects of waveform, frequency and initial phase on the dynamic response. The deformation period is identical with the electric period for the pulsed DC electric field but the deformation period is half of the electric period for the sinusoidal electric field. As the frequency increases, the maximum deformation degree D max first climbs steadily to a peak value, then decreases steeply and finally approaches an equilibrium value. The maximum D max appears at f = 50 Hz for the pulsed DC electric field and appears at f = 100 Hz for the sinusoidal electric field according to numerical results. These results are helpful for the optimization of electro-coalescence.
Kai Guo,Xiaoya Liu,Ling Du,Yuling Lü,Xiaoming Luo,Xiao Ling
Electromagnetic synergy is a more effective physical method than a single AC electric field (ACEF) to enhance oil–water separation. However, the electrocoalescence behavior of droplets dispersed with salt ions in oil under the synergistic electromagnetic field (EMSF) still lacks research. Herein, the evolution coefficient of liquid bridge diameter (C1) characterizes the growth rate of the liquid bridge diameter, a series of Na2CO3-dispersed droplets with different ionic strengths were prepared, and C1 values of droplets under ACEF and EMSF were compared. Micro high-speed experiments revealed that C1 under ACEF is larger than C1 under EMSF. In particular, when σ = 100 μS·cm–1and E = 629.73 kV·m–1, C1 under the ACEF is 15% larger than C1 under EMSF. Additionally, the theory of ion enrichment is put forward, which explains the influence of salt ions on ζ potential and total surface potential in EMSF. This study provides guidance for designing high-performance devices by introducing electromagnetic synergy in water-in-oil emulsion treatment.
危险品化学品经营许可证（带存储）