Deformation and vibration of droplet in oil subjected to a chaotic-pulse-width-modulation electric field

Abstract

The pulsed electric field with constant frequency has difficulty exerting the maximum demulsification potentiality, because dynamic changes in droplet size during the electric demulsification process lead to the uncertainty of the optimal demulsification frequency. Thus, a chaotic-pulse-width-modulation (CPWM) electric field with a chaotic change of the pulse width and constant duty cycle is proposed for oil demulsification. The deformation and vibration of droplets in oil subjected to the CPWM electric field affects the efficiency of droplet coalescence and demulsification. Therefore, a model of droplet deformation and vibration in oil is established, and the effects of the duty cycle and electric field intensity on droplet vibration deformation are analyzed. The results show that the CPWM electric field has a wide frequency range and can cover the parametric resonance frequency of the droplet. The droplet has three different frequencies (ωe>ωr, ωe≈ωr, ωe<ωr) under the action of CPWM electric field, and the droplet deformation has chaotic characteristics. Considering the droplet deformation vibration and chaotic characteristics, the optimal duty cycle is 0.5 when using CPWM electric field demulsification. With increasing electric field intensity, the vibration amplitude of the droplet increases, and when the electric field intensity exceeds a certain value, the chaotic degree of the droplet deformation will decrease.