CFD simulation of ultrasonic atomization pyrolysis reactor: the influence of droplet behaviors and solvent evaporation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jian Wang ◽  
Jichuan Wu ◽  
Shouqi Yuan ◽  
Wei-Cheng Yan
Keyword(s):  
Flow Pattern ◽  
Size Distribution ◽  
Droplet Size ◽  
Cfd Simulation ◽  
Collection Efficiency ◽  
Great Influence ◽  
Droplet Size Distribution ◽  
Solvent Evaporation ◽  
Droplet Collision ◽  
Ultrasonic Atomization

Abstract Previous work showed that particle behaviors in ultrasonic atomization pyrolysis (UAP) reactor have a great influence on the transport and collection of particles. In this study, the effects of droplet behaviors (i.e. droplet collision and breakage) and solvent evaporation on the droplet size, flow field and collection efficiency during the preparation of ZnO particles by UAP were investigated. The collision, breakage and solvent evaporation conditions which affect the droplet size distribution and flow pattern were considered in CFD simulation based on Eulerian-Lagrangian method. The results showed that droplet collision and breakage would increase the droplet size, broaden the droplet size distribution and hinder the transport of droplets. Solvent evaporation obviously changed the flow pattern of droplets. In addition, both droplet behaviors and solvent evaporation reduced the collection efficiency. This study could provide detail information for better understanding the effect of droplet behaviors and solvent evaporation on the particle production process via UAP reactor.

scholarly journals The enhancement of droplet collision by electric charges and atmospheric electric fields

2021 ◽  
Vol 21 (1) ◽  
pp. 69-85
Author(s):  
Shian Guo ◽  
Huiwen Xue
Keyword(s):  
Size Distribution ◽  
Electric Fields ◽  
Droplet Size ◽  
Cloud Droplet ◽  
Droplet Size Distribution ◽  
Droplet Radius ◽  
Electrostatic Effects ◽  
Droplet Collision ◽  
Aerosol Effect ◽  
Cloud Droplet Size Distribution

Abstract. The effects of electric charges and fields on droplet collision–coalescence and the evolution of cloud droplet size distribution are studied numerically. Collision efficiencies for droplet pairs with radii from 2 to 1024 µm and charges from −32 r2 to +32 r2 (in units of elementary charge; droplet radius r in units of µm) in different strengths of downward electric fields (0, 200, and 400 V cm−1) are computed by solving the equations of motion for the droplets. It is seen that the collision efficiency is increased by electric charges and fields, especially for pairs of small droplets. These can be considered as being electrostatic effects. The evolution of the cloud droplet size distribution with the electrostatic effects is simulated using the stochastic collection equation. Results show that the electrostatic effect is not notable for clouds with the initial mean droplet radius of r¯=15 µm or larger. For clouds with the initial r¯=9 µm, the electric charge without a field could evidently accelerate raindrop formation compared to the uncharged condition, and the existence of electric fields further accelerates it. For clouds with the initial r¯=6.5 µm, it is difficult for gravitational collision to occur, and the electric field could significantly enhance the collision process. The results of this study indicate that electrostatic effects can accelerate raindrop formation in natural conditions, particularly for polluted clouds. It is seen that the aerosol effect on the suppression of raindrop formation is significant in polluted clouds, when comparing the three cases with r¯=15, 9, and 6.5 µm. However, the electrostatic effects can accelerate raindrop formation in polluted clouds and mitigate the aerosol effect to some extent.

INFLUENCE OF VISCOSITY ON DROPLET SIZE DISTRIBUTION AND GENERATION RATE IN ULTRASONIC ATOMIZATION

2010 ◽  
Vol 20 (11) ◽  
pp. 923-934 ◽  
Author(s):  
Antonio Lozano ◽  
Juan Antonio Garcia ◽  
Jose Luis Navarro ◽  
Esteban Calvo ◽  
Felix Barreras
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Generation Rate ◽  
Ultrasonic Atomization

Evaluation of Droplet Sizing Methods for Aerosols

2012 ◽  
Author(s):  
P. J. Brizio ◽  
M. D. Protheroe ◽  
A. M. Al-Jumaily
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Optical Method ◽  
Droplet Size Distribution ◽  
Laser Diffraction ◽  
Ease Of Use ◽  
Water Aerosol ◽  
Ultrasonic Atomization ◽  
Expensive Equipment

Three methods of determining the droplet size distribution in aerosols are investigated. These are based on using photography, impact/capture and optics, respectively, to determine the droplet size distribution in an air-water aerosol produced from an ultrasonic atomization device. Comparison is made between these methods based on the required procedure, equipment used and results obtained. An optical method, based on laser diffraction, stands out in terms of accuracy and ease of use although it requires relatively expensive equipment.

MODELING DROPLET SIZE DISTRIBUTION NEAR A NOZZLE OUTLET IN AN ICING WIND TUNNEL

2006 ◽  
Vol 16 (6) ◽  
pp. 673-686 ◽  
Author(s):  
Laszlo E. Kollar ◽  
Masoud Farzaneh ◽  
Anatolij R. Karev
Keyword(s):  
Wind Tunnel ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Size Distribution ◽  
Nozzle Outlet
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