Taylor cone jets

Figure 22.5 shows the acting force in formation of the conical jet. In Taylor cone-jet mode, the force on the surface of the cone is assumed to be at equilibrium at all points except near the apex, where the jet of charged fluid accelerates under the tangential forces. In this mode, three... 

Xie, J. and C.-H. Wang. Encapsulation of proteins in biodegradable polymeric microparticles using electrospray in the Taylor cone-jet mode. Biotechnology and Bioengineering 97(5) (2007) 1278-1290. 

Chemey, L.T. (1999) Stmcture of the taylor cone jets limit of low flow rates. /. Fluid. Mech., 378, 167-196. 

The size distributions of colloidal suspensions of nanoparticles 74 nm to 14 nm in diameter are analyzed on-line. The sols are first diluted in water seeded with enough TFA to attain electrical conductivities in the range of 0.01 S/m. The solution is then finely dispersed into an atmosphere of CO2 via a Taylor cone-jet. The resisting electrospray of ultrafine droplets dries, transferring the solution particles virtually uncontaminated into the gas. There they are sized by means of a differential mobility analyzer and an inertial impactor of unusually high resolution. The technique is first tested successfully with previously calibrated monodisperse polystyrene latex (PSL) spheres 74 to 21 nm in diameter. It is then used to size a solution of colloidal silica with particle diameters nominally between 10 and 14 nm. 

Taylor Cone-Jets and Electrospray Mass Spectrometry (ESMS). 

Ganan-Calvo, A.M., ReboUo-Munoz, N., Montanero, J.M., 2013. The minimum or natural rate of flow and droplet size ejected by Taylor cone-jets physical symmetries and scaling laws. New Journal of Physics 15, 033035. 

Cherney, L. T. Structure of the Taylor cone jets Limit of low flow rates. J. Fluid. Meek 1999, 378, 167-196. 

Fig. 11.11. Schematic of Taylor cone formation, ejection of a jet, and its disintegration into a fine spray. The electrochemical processes of ESI [77,78] are also assigned. Adapted from Ref. [49] by permission of the authors.

Fig. 11.12. Electrospray from a nanoESI capillary. The jet emitted from the Taylor cone is clearly visible and separate from the region of rapid expansion into a plume of microdroplets. By courtesy of New Objective, Woburn, MA.

Electrospray, also called electrohydrodynamic or electrostatic spray, is an atomization technique in which liquids are dispersed solely by the application of high voltages. A simple electrospray setup is shown in Fig. 4. A liquid flows into a metal capillary tube charged to the kilovolt range and emerges from the tip as a conical meniscus, known as a Taylor cone, due to the intense electric field (Fig. 5). An unstable jet extends continuously from the apex of the cone and disperses into charged droplets further downstream. Electrosprays have been used in industrial... 

Fig. 5.3. A photograph of the spray generated in an electrospray ionization source (top) and a schematic view of the processes involved (bottom). From the Taylor cone, a jet is emitted and expands to a plume of micrometer-sized charged droplets from which finally desolvated ions are produced.

Yarin, A.L., Koombhongse, S., and Reneker. D.H., 2001b, Taylor cone and jetting from liquid droplets in electrospinning of nanofibers, J. Appl. Phys.. 9(90), pp. 4836-4845. 

Figure 4.2 Schematic illustration of the conventional set-up for electrospinning. The insets show a drawing of the electrified Taylor cone, bending instability, and a typical SEM Image of the nonwoven mat of PET nanofibers deposited on the collector. The bending Instability Is a transversal vibration of the electrospinning jet. It is enhanced by electrostatic repulsion and suppressed by surface tension...

The jet of liquid then breaks into fine monodisperse droplets. This is the preferred mode of atomization because it continuously produces stable uniform particles. Studies have shown that this mode is the preferred operating regime for particle production because it produces particles with a narrow size distribution. This type of cone is known as the Taylor cone after the researcher who theoretically demonstrated the existence of conical menisci. ... 

FIGURE 22.5 Forces acting on the Taylor cone in EHDA process. (Reprinted from J. Aerosol ScL, 30(7), Hartman, R.P.A., Bruimer, D.J., Camelot, D.M.A., Marijnissen, J.C.M., and Scarlett, B., Electrohydrodynamic atomization in the cone-jet mode physical modeling of the liquid cone and jet, 823-849. Copyright 1999, with permission from Elsevier.)... 

Ganan-Calvo, A.M. Cone-Jet analytical extension of Taylor s electrostatic solution. The asymptotic universal scaling laws in electrospraying of liquids, in APS Division of Fluid Dynamics Meeting Abstracts, San Francisco, CA, 1997. 

Electrospinning uses a high-voltage electrical field (typically 10-20 kV) to form micro- and even nanoscale fibres from a suspended droplet of polymer melt or solution [118]. When the repulsive electrostatic interactions overcome the droplet s surface tension, a Taylor cone is formed and a polymer jet is ejected from the tip of this Taylor cone [119]. The polymer jet is then accelerated towards a grounded collector screen. As the jet moves through the air, a stretching process occurs and the solvent evaporates which results in a non-woven polymer fabric or polymer mat [120]. Electrospinning has already been applied for both synthetic as well... 

An elongational rheometer developed in [26] based on this principle revealed that the initial longitudinal stress created by the electric stretching of a polymeric jet as it transforms from the modified Taylor cone to a thin jet, is of the order of 10-100 kPa. These values are one or two orders of magnitude larger than those measured for the uncharged viscoelastic jets. The rheometer also allows evaluatimi of the modulus of elasticity and relaxation time of concentrated polymer solutions and melts. 

Keywords Aerodynamic effects Charged droplets Cone jet Droplet evaporation Droplet deformation Electrohydrodynamic spray Electrospray Ion source Mass spectrometry Mass spectroscopy Rayleigh charge limit Spray modes Taylor cone... 

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