scholarly journals Numerical Simulations of Molten Breakup Behaviors of a de Laval-Type Nozzle, and the Effects of Atomization Parameters on Particle Size Distribution

Processes ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1027
Author(s):  
Lianghui Xu ◽  
Xianglin Zhou ◽  
Jinghao Li ◽  
Yunfei Hu ◽  
Hang Qi ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Gas Flow ◽  
Nozzle Geometry ◽  
Particle Model ◽  
Process Conditions ◽  
Operating Pressure ◽  
Gas Temperature ◽  
Tracking Model

In this work, an atomizer with a de Laval-type nozzle is designed and studied by commercial computational fluid dynamics (CFD) software, and the secondary breakup process during atomization is simulated by two-way coupling and the discrete particle model (DPM) using the Euler-Lagrange method. The simulation result demonstrates that the gas flow patterns greatly change with the introduction of liquid droplets, which clearly indicates that the mass loading effect is quite significant as a result of the gas-droplet interactions. An hourglass shape of the cloud of disintegrating molten metal particles is observed by using a stochastic tracking model. Finally, this simulation approach is used for the quantitative evaluation of the effects of altering the atomizing process conditions (gas-to-melt ratio, operating pressure P, and operating gas temperature T) and nozzle geometry (protrusion length h, half-taper angle α, and gas slit nozzle diameter D) on the particle size distribution of the powders produced.

Study on Coal Particle Combustion Characteristics and NO Emission in a Hot Laminar Gas Flow

2017 ◽  
Author(s):  
MingYan Gu ◽  
Dawei Yan ◽  
XianHui He ◽  
Dan Yan ◽  
FengShan Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Coal Particle ◽  
Gas Flow ◽  
Combustion Process ◽  
Mass Ratio ◽  
Gas Temperature ◽  
Uniform Size ◽  
Coal Particles

The combustion and NO formation characteristics of coal particles of different size distributions in a laminar gas flow were investigated by numerical simulation. The variation of coal particle size distribution was obtained by changing the mass ratio of small-sized coal to large-sized coal. The gas-phase combustion was modeled using GRI-Mech 3.0. The particle motion was simulated using a trajectory model. The results show that the coal particle size distribution has a significant impact on combustion process and NO distribution. Coal particles of uniform size at either 105 or 75 μm results in a higher NO concentration than coal consisting of both the large and the small particles. The smaller-sized coal particles experience a rapid volatile release, a higher maximum gas temperature, and a higher maximum NO concentration. Increasing the mass ratio of the smaller-sized coal particles changes the gas temperature and the averaged NO distribution and lowers the maximum NO concentration.

scholarly journals Encapsulation of Menthol in Beeswax by a Supercritical Fluid Technique

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Linjing Zhu ◽  
Hongqiao Lan ◽  
Bingjing He ◽  
Wei Hong ◽  
Jun Li
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Flow Rate ◽  
Saturated Solution ◽  
Narrow Particle Size Distribution ◽  
Solution Flow Rate ◽  
Process Conditions ◽  
Solution Flow ◽  
Expansion Temperature

Encapsulation of menthol in beeswax was prepared by a modified particles from gas-saturated solutions (PGSS) process with controlling the gas-saturated solution flow rate. Menthol/beeswax particles with size in the range of 2–50 μm were produced. The effects of the process conditions, namely, the pre-expansion pressure, pre-expansion temperature, gas-saturated solution flow rate, and menthol composition, on the particle size, particle size distribution, and menthol encapsulation rate were investigated. Results indicated that in the range of studied conditions, increase of the pressure, decrease of the gas-saturated solution flow rate, and decrease of the menthol mass fraction can decrease the particle size and narrow particle size distribution of the produced menthol/beeswax microparticles. An N2-blowing method was proposed to measure the menthol release from the menthol/beeswax microparticles. Results showed that the microparticles have obvious protection of menthol from its volatilization loss.

scholarly journals Optimium conditions for the production of sub-micron cobalt power

2015 ◽  
Author(s):  
◽  
Andricia Hareepersad
Keyword(s):  
Particle Size ◽  
Response Surface Methodology ◽  
Particle Size Distribution ◽  
Design Of Experiments ◽  
Response Surface ◽  
Size Distribution ◽  
Process Conditions ◽  
Cobalt Powder ◽  
Optimal Response ◽  
Factor Design

Cobalt powder is a grey metallic powder that is produced by the thermal decomposition and reduction of a cobalt compound. The challenge faced by Shu Powders Africa was that sub-micron cobalt powder had never been produced in a two-step furnace by any manufacturer in the cobalt powder industry. Hence there was no prior information to guide this type of processing. Therefore this research set out to investigate the production of sub-micron cobalt powder through a two-step furnace to determine the optimum parameters for this process. For the company to remain competitive, it was imperative to begin producing sub-micron cobalt powder. Sub-micron cobalt powder is much more valuable and profitable to produce. The second production line would be operational due to the production of sub-micron cobalt powder hence creating job opportunities for the local community. Sub-micron cobalt powder shares the same chemical composition and physical characteristics as cobalt powder. The only differences are particle size (0.60 - 0.90 µm), oxygen content (0.30 - 0.80%) and the microscopic structure which is the particle size distribution d90 (7 - 10 µm). The approach taken was to understand the variables that had a large effect on the powder. The effects needed to be established by determining how it impacted on the quality of the powder which is pertinent to making sub-micron cobalt powder. Due to the experience in producing cobalt powder, variables that had a large effect on normal cobalt powder production were assumed to be the same variables that would impact the production of sub-micron cobalt powder. Some of these effects were also confirmed by literature. A strategy of statistical design of experiments was used to evaluate the conditions for sub-micron cobalt powder production. Design of experiments assisted in planning the experimental design matrices for both experiments. For the furnace experimentation a 24 factor design was selected. For the jet mill experimentation a 23 factor design was selected. Response surface methodology was used to determine optimum ranges of the variables at various process conditions. The central composite rotatable design laid out the design in which the variables interacted with one another at different process conditions. Evaluation of results was based on the generated model. Models such as the 3D surface model, cubic model and the contour model were generated to graphically illustrate the effects that the variables have on the response. Analysis of furnace data indicated that the optimal response was achieved at a temperature range (445 - 460)°C, hydrogen gas range (225 - 250) Nm3/h, belt speed (80 - 90) mm/min, and carbon dioxide gas range (80 - 90) Nm3/h. Analysis of the jet mill experimental data indicated that the optimal response particle size distribution, was achieved at a classifier speed range of (5500 - 6000) rpm, AFG grinding bin range (30 - 35) kgs and grinding gas pressure of (4.0 - 4.5) bar. The study confirms the efficiency of a two-step furnace to produce sub-micron cobalt powder at high volumes. The advantage of the two-step furnace was the increased throughput of 2.3-2.7 tons/day whilst in industry furnace throughputs are 1.3-1.6 tons/day. This represented a 60% increase in productivity over conventional furnaces. The response surface methodology also proved to be a suitable technique for process optimization.

Effect of coal particle size distribution on packed bed pressure drop and gas flow distribution

Fuel ◽  
2006 ◽  
Vol 85 (10-11) ◽  
pp. 1439-1445 ◽  
Author(s):  
M KEYSER ◽  
M CONRADIE ◽  
M COERTZEN ◽  
J VANDYK
Keyword(s):  
Particle Size ◽  
Pressure Drop ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Coal Particle ◽  
Gas Flow ◽  
Flow Distribution ◽  
Packed Bed

Determining Aerosol Particle Size Distribution Using Time-Resolved Laser-Induced Incandescence

2006 ◽  
Author(s):  
K. J. Daun ◽  
B. J. Stagg ◽  
F. Liu ◽  
G. J. Smallwood ◽  
D. R. Snelling
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Nano Particles ◽  
Solution Stability ◽  
Gas Temperature ◽  
Time Resolved ◽  
Laser Induced Incandescence ◽  
Ill Posed ◽  
Aerosol Volume

Time-resolved laser-induced incandescence is a powerful tool for determining the physical characteristics of aerosol dispersions of refractory nano-particles. In this procedure, particles within a small aerosol volume are heated with a nano-second laser pulse, and the temporal incandescence of the particles is then measured as they return to the ambient gas temperature. It is possible to infer particle size distribution from the temporal decay of the LII signal since the cooling rate of an individual particle depends on its area-to-volume ratio. This requires solving a mathematically ill-posed inverse problem, however, since the measured LII signal is due to the incandescence contributed by all particle sizes within the aerosol volume. This paper reviews techniques proposed in the literature for recovering particle size distributions from time-resolved LII data. The characteristics of this ill-posed problem are then discussed in detail, particularly the issues of solution stability and uniqueness. Finally, the accuracy and stability of each method is evaluated by performing a perturbation analysis, and the overall performance of the techniques is compared.

Synthesis of Titania Powder by Titanium Tetrachloride Oxidation in an Aerosol Flow Reactor

1991 ◽  
Vol 249 ◽  
Author(s):  
M. Kamal Akhtar ◽  
Yun Xiong ◽  
Sotiris E. Pratsinis
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Residence Time ◽  
Titanium Tetrachloride ◽  
Flow Reactor ◽  
Geometric Standard Deviation ◽  
Process Conditions ◽  
Average Particle ◽  
Powder Size

ABSTRACTVapor phase synthesis of titania particles by oxidation of titanium tetrachloride (TiCI4) was studied in an aerosol reactor between 1200 K and 1723 K. The effect of process variables (reactor residence time, temperature, reactant concentration) on powder size and phase characteristics was investigated using the differential mobility particle sizer, scanning electron microscopy and X-ray diffraction. The morphology of the particles remained unchanged under the process conditions investigated; titania particles were primarily anatase though the rutile weight fraction increased with increase in reactor temperature. The geometric number average diameter of the particles was between 0.13 µm and 0.35 [m and the geometric standard deviation of the particle size distribution was about 1.4. The average particle size increased with increasing temperature, TiCI4 concentration and residence time. The observed changes in the particle size distribution were compared with those predicted by solving the aerosol dynamic equation by a sectional method and accounting for coagulation and first order chemical reaction.

Effect of Nozzle Geometry on Particle Size Distribution in Atomized Spray of Metastable Superheated Liquid

2019 ◽  
Vol 28 (4) ◽  
pp. 538-541
Author(s):  
Yu. A. Zeigarnik ◽  
V. I. Zalkind ◽  
L. V. Nizovskii ◽  
V. L. Nizovskii ◽  
S. S. Shchigel
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Nozzle Geometry ◽  
Superheated Liquid
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