277221 Break-up Patterns and Conditions of Water Droplet in High-Voltage High-Frequency Pulse Electric Field

Thursday, November 1, 2012: 10:35 AM
412 (Convention Center )
Zhiqian Sun, College of Chemical Engineering, China University of Petroleum (East China), Qingdao, China

Break-up behavior of water droplets in emulsion under high electric field is one of the most important phenomena during electrocoalescence process. Many processes, such as demulsification of W/O emulsion and electrical dispersion, are accompanied with tear-up of water droplets and rupture of oil-water interfacial film. However, electrostatic break-up mechanism of droplets still lacks of comprehensive and in-depth analysis up to the present. Consequently, the microscopic experimental study was carried out to investigated the break-up patterns and conditions of water droplet in high-voltage high-frequency pulse electric field comprehensively in this paper. Microscopic experimental results indicated that, there are mainly three break-up patterns of droplet in high-voltage high-frequency pulse electric field: break-up at one pole, break-up at both poles and break-up in middle part. When electrostatic tensile stress exceeds additional compressive stress formed by interfacial tension at the pole of polarizational droplet, top or bottom of the droplet broken up, spraying out a series of tiny droplets with particle size of 1 to 3 microns, which called “break-up at one pole”. With electric field strength increasing, both poles of the water droplet break up, which called “break-up at both poles”. When electric field strength increases further, droplet is quickly stretched and deformed, the middle of the droplet is stretched to filamentous shape and then forms a string of small water chain with particle size ranging from several microns to tens of microns, which called “break-up in middle part”. Subsequently, combined with microscopic experimental results, the conditions of droplet polarization, break-up at pole(s) and break-up in middle part under high-voltage high-frequency pulse electric field were obtained on the basis of theoretical analysis. The research results laid good foundation for further investigation of high-voltage high-frequency electrostatic emulsion-breaking mechanism.

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See more of this Session: Emulsions and Foams I
See more of this Group/Topical: Engineering Sciences and Fundamentals