Droplet Size Characteristics and Energy Input Requirements of Emulsions Formed Using High-Intensity-Pulsed Electric Fields

Abstract

Experimental methods have been developed to measure droplet size characteristics and energy inputs associated with the rupture of aqueous droplets by high-intensity-pulsed electric fields. The combination of in situ microscope optics and high-speed video cameras allows reliable observation of liquid droplets down to 0.5 ym in size. Videotapes of electric-field-created emulsions reveal that average droplet sizes of less than 5 urn are easily obtained in such systems. Analysis of the energy inputs into the fluids indicates that the electric field method requires less than \% of the energy required from mechanical agitation to create comparable droplet sizes.

Biodesulfurization of dibenzothiophene and crude oil using electro-spray reactors

“…The average power consumption was found to be 7.4 W which corresponds to approximately 3 W/L and is in agreement with previously published values for the EPC (18,22). This power is significantly smaller than that needed by mechanical agitation to produce the same size droplets (18).…”

“…Typically, impeller based reactors are capable of achieving water or oil droplet sizes of 100 -300 pm in diameter and require on the order of 1-6 WL, to do so based upon empirical correlations (17). It is estimated that if impeller based systems were capable of producing 5 pm droplets, it would require -25 kWL, (18). Furthermore, no capacity exists for biocatdyst separation or emulsion breakage within the reactor.…”

“…In this concept, the differing electrical conductivity between the aqueous and organic phases causes electrical forces to be focused at the liquid / liquid interface, creating tremendous shear force (see for example (24)). This shear causes the conductive phase to be dispersed (5 pm droplet size - (18)) into the non-conductive phase, but does so with decreased energy requirements relative to mechanical agitators due to the fact that energy is imparted only at the liquid / liquid interface and not the entire bulk solution (see (19) for a review). The configuration of the EPC developed at the Oak Ridge National employs two different types of electrode regions in order to increase liquid throughput.…”

Electric fields enable tunable surfactant transport to microscale fluid interfaces

“…Electric fields act across fluid-fluid interfaces in electrocoalescence [1,2], inkjet printing [3,4], electroemulsification [5][6][7], and microfluidic devices [8][9][10][11]. These systems typically consist of drops of one fluid dispersed in another, with surfactants adsorbing from the bulk phases to the interface.…”

Effects of low-amplitude forced oscillation on the rate of mass transfer to circulating liquid droplets

“…Experiments have been carried out in two general areas: (1) the use of high-amplitude oscillations, which lead to droplet breakup and/or emulsification (Scott, 1987;Scott and Sisson, 1988;Scott and Wham, 1989) and (2) the use of stable oscillations for the alteration of velocity profiles (Scott, 1986;Wham and Byers, 1987;Scott et al, 1990). Experiments have been carried out in two general areas: (1) the use of high-amplitude oscillations, which lead to droplet breakup and/or emulsification (Scott, 1987;Scott and Sisson, 1988;Scott and Wham, 1989) and (2) the use of stable oscillations for the alteration of velocity profiles (Scott, 1986;Wham and Byers, 1987;Scott et al, 1990).…”