Study On Dynamic Characteristics Of Emulsified Oil Droplets Based On Chaotic Electric Field

Lubricating oil is easily polluted by water to form industrial waste oil due to physical,chemical and artificial factors during transportation and use.As a kind of great-value and renewable energy resources,industrial waste oil has great economic benefits and environmental protection significance.Demulsification and dewatering of waste oil is the key to its resource utilization,and pulsed electric field demulsification has the advantages of cleaning,high efficiency and energy saving.However,the common constant frequency pulse electric field cannot meet the requirements of the optimal demulsification frequency change in the demulsification process.Therefore,the pulsed electric field with chaotic frequency is proposed to treat the demulsification and dewatering of industrial waste oil.Due to the chaotic variation of the electric field frequency corresponds to the optimum demulsification frequency,the droplets can response at their own resonance frequency to realize rapid coalescence demulsification.Given that the deformation mechanism of droplet in emulsion oil under the chaotic pulsed electric field is unclear,this study focuses on the dynamic characteristics of droplet deformation under the action of chaotic pulsed electric field.Firstly,the chaotic pulse position modulation（CPPM）electric field scheme with constant amplitude and equal pulse width and the chaotic pulse group（CPG）electric field scheme with constant amplitude and equal duty cycle are constructed by the chaotic pulse position modulation method.And then,the droplet deformation dynamic model under the chaotic pulsed electric field is established by applying the finite element method,and phase field method is used to capture the evolution of moving interface.The dynamic characteristic of the droplet and the influence of electric field parameters on the droplet deformation are revealed.The results shows that the deformation of droplet in oil is nonstationary vibration with the action of the CPPM electric field,and its deformation is chaotic vibration.The chaos of droplet deformation decreases with the increase in pulse width.The deformation ratio of droplet can be increased by increasing the electric field intensity,but the droplet are easy to split and the deformation is no longer chaotic at high electric field intensity.Furthermore,the mechanism of droplet relaxation in CPG electric field is investigated,and the influences of duty cycle and group pulse number on droplet deformation are analyzed.Results show that the CPG electric field can make the droplet tends to be resonant and steady vibration,and its steady vibration mainly depends on the consistency of the state of the droplet after the end of the latter pulse with that of the former pulse.The optimal duty cycle of droplet resonance is 0.5,and the optimal number of pulses to achieve steady vibration is 3.Finally,the experiment of droplet vibration and deformation in oil excited by chaotic pulse electric field is carried out.The results show that the numerical results of droplet deformation are in good agreement with the experimental results,and the simulation results of this study are reasonable.This study reveals the deformation dynamic behavior and chaotic characteristics of droplets in chaotic pulsed electric field,as well as the influence of electric field parameters on droplet deformation.The purpose is to improve the research on the dynamic mechanism of chaotic electric field demulsification,lay a theoretical foundation for the method of chaotic frequency pulsed electric field demulsification and dewatering,and lay a technical support for the design of high-efficiency demulsification and dewatering device.