Generation of Monodisperse Micron‐Sized Droplets using Free Adjustable Signals

Riefler, Norbert; Wriedt, Thomas

doi:10.1002/ppsc.200700038

Cited by 32 publications

(11 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The set‐up for the single burning droplet experiments that has been described in detail by Rosebrock et al is shown schematically in Figure . It consists of the droplet‐on‐demand generator (piezodropper) and a square cuvette. Single monodisperse droplets are ejected upward in coflowing 0.4 L/min oxygen (purity 99.95%) and ignited by a synchronized spark discharge.…”

Section: Methodsmentioning

confidence: 99%

The role of microexplosions in flame spray synthesis for homogeneous nanopowders from low‐cost metal precursors

et al. 2015

Self Cite

View full text Add to dashboard Cite

One of the most versatile and rapid manufacturing processes for a variety of nanopowders is flame spray pyrolysis (FSP). The production costs of this scalable process are largely controlled by the raw materials, pushing for the utilization of lowcost metal precursors. These, however, typically yield inhomogeneous products containing large particles up to micrometer size along with fine nanoparticles. Here, the release mechanism of nitrate and carboxylate precursors from spray droplets has been investigated by single-droplet combustion experiments and thermogravimetric analysis. The results show that neither precursor evaporation nor choice of solvents is prerequisite for homogeneous nanopowders but droplet microexplosions with continuing combustion. It is shown that even low-cost metal nitrates yield homogeneous nanopowders if precursors are formulated such that droplet microexplosions occur by internal superheating. The proposed precursor release mechanisms are verified with lab-and pilot-scale FSP, demonstrating that single-droplet combustion experiments can be employed to predict the product quality.

show abstract

Section: Methodsmentioning

confidence: 99%

The role of microexplosions in flame spray synthesis for homogeneous nanopowders from low‐cost metal precursors

et al. 2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…Isolated monodisperse droplets are produced with a piezoelectric generator (piezodropper) 27,28 at a frequency of 4 Hz . The separation distance of two successive d 0 5100 lm droplets is s51875 d 0 , which diminishes droplet interference that would otherwise occur for s 100 d 0 in normal air 29 and elevated oxygen concentrations.…”

Section: Experimental Layoutmentioning

confidence: 99%

Disruptive burning of precursor/solvent droplets in flame‐spray synthesis of nanoparticles

et al. 2013

Self Cite

View full text Add to dashboard Cite

Flame spray pyrolysis is an established technique for synthesizing nanoparticles in the gas phase through aerosol combustion of precursor/solvent droplets. The combustion characteristics of isolated micron-sized precursor/solvent droplets are investigated experimentally. Pure solvent droplets burn uniformly and classically quasisteady, whereas precursor/ solvent droplets manifest disruptive combustion behavior. The fast onset of droplet disruption, which occurs only for solutions with dissolved metal precursors, is not due to solid-particle precipitation within the droplet. Instead, the mechanism of disruptive droplet burning is similar to that of slurry droplets, consisting of three main steps: (1) diffusioncontrolled burning of the high-volatile solvent, (2) viscous-shell formation due to decomposition of the low-volatile metal precursor, and (3) subsequent disruption due to heterogeneous nucleation. The time sequence of the three steps depends on the concentration and decomposition characteristics of the metal precursor, shortening with increased concentration and higher incremental decomposition temperature.

show abstract

“…In order to image a droplet, the droplet ejection was triggered with the camera [14] using the software package Motion Studio (IDT, Lommel, Belgium, version: 2.09, 2011). For the purpose of achieving a 10.5 mm x 8.4 mm field of view (FOV), which is necessary for tracking and analyzing the smallest spray droplets as found in the real spray application, a K2/SC long-distance microscope lens (Infinity, USA) was selected [15].…”

Section: Image Acquisition Systemmentioning

confidence: 99%

Measurement of Single Droplet Characteristics using High Speed Imaging Techniques

Minov¹,

Cointault²,

Vangeyte³

et al. 2013

Computer Graphics and Imaging / 798: Signal Processing, Pattern Recognition and Applications

View full text Add to dashboard Cite

The spray droplets generated by agricultural nozzles play an important role in the application accuracy and efficiency of plant protection products. But, the process of generating and controlling small droplets of high uniformity, constant size and form is complex and difficult to quantify or model. The limitations of the nonimaging techniques and the recent improvements in digital image acquisition and processing increased the interest in using high speed imaging techniques in pesticide spray characterisation. The goal of this study was to apply an imaging technique to evaluate the characteristics of a single spray droplet using a piezoelectric single droplet generator in a dropleton-demand mode with 4 glass nozzles and a high speed imaging technique. Tests were done with a high-speed camera, microscope lenses, and a xenon light source. Image analysis algorithms were developed for droplet sizing and tracking on images gained from this acquisition system. The experiments have shown that using the selected image acquisition and processing system, different droplet sizes and velocities can be measured. By changing the pulse width and the nozzle orifice size, repeatable droplets could be generated with a size ranging from 135 μm up to 461 μm. The ratio between droplet diameter and nozzles orifice opening varied from 1.33 up to 3.42 depending on the settings.

show abstract

Generation of Monodisperse Micron‐Sized Droplets using Free Adjustable Signals

Cited by 32 publications

References 19 publications

The role of microexplosions in flame spray synthesis for homogeneous nanopowders from low‐cost metal precursors

The role of microexplosions in flame spray synthesis for homogeneous nanopowders from low‐cost metal precursors

Disruptive burning of precursor/solvent droplets in flame‐spray synthesis of nanoparticles

Measurement of Single Droplet Characteristics using High Speed Imaging Techniques

Contact Info

Product

Resources

About