Particle Distribution Behavior Research Articles

Distribution behavior of particles in vibratory finishing within restricted space: Force characteristics and posture control

Particles are the primary abrasive media for vibratory finishing, and the contact force embodies the particle action to the finished surface. In this work, the measured and simulated normal forces were compared, the dominant form of particle action on the workpiece's surface was analyzed, and the effect of pipe-cavity's posture on the distribution behavior of the particles-to-wall normal force was investigated. It is found that the measured normal force has the same force characteristic of frequency multiplication as the simulated force, and the simulation results can reflect the finishing pattern. The normal action of particles on the surface, the normal force, can make the cavity surface form a lower surface roughness faster than the tangential action. The posture control can change the distribution behavior of the particles to achieve all-around finishing, and the optimal posture range is >60° in polar and between 60° and 90° in azimuth angle.

The Spectroscopic and Antimicrobial Yield of Sol-Gel Derived Zinc Copper Silicate/E102 Nanoclusters

The structural and optical properties of 30 ZnO: 50 SiO2: (20-x) CuO (ZSC) loaded with E102 (tartrazine dye) (where x = 0.02, 0.05, 0.07 wt.%) nanoclusters have been explored. These nanoclusters were synthesized by a sol-gel route followed by a very controlled crystallization process at 500 °C. The phase formation, structural modification, and particle distribution behavior of these nanoclusters have been studied using XRD and TEM analysis to monitor the domestic environment for ZCS-E102. The optical transmission and reflection properties of nanoclusters in the UV–Vis-NIR range were studied for the present nanoclusters from which the optical absorption was calculated. Tauc method is employed to estimate the type and value of energy needed to gap transition from absorption data. The direct and indirect gap shows decreased energy need for its transition by E102 concentration increase. The antimicrobial potentials of four synthesized nanoclusters were performed against some pathogenic microbes. The toxicity performance of all studied nanoclusters is measured. Results revealed that ZSC-0.07E102 is showed an effective antimicrobial action against four tested pathogenic microbes in terms of excellent inhibitory effect and biocompatibility show noticeable potential in the antimicrobial application. Therefore, this proficient nanomaterial is a promising choice for biomedical purposes.

Prediction of distribution behavior of particles with wide size distribution in baffled fluidized beds

Multi-baffle fluidized beds are recognized as efficient for controlling the difference in the mean residence time (MRT) of particles with a wide size distribution (WSD). Modeling the MRT of the particles of the each size is of great importance in the design of baffled fluidized beds for various applications. An analogy to the gas-liquid distillation model, based on the relative elutriation degree, was proposed herein for predicting the MRT of the particles of each size. The model was validated by comparison of the predicted and measured composition of the particles of each size in baffle-free and baffled fluidized beds. Moreover, the effects of the gas velocity, number of baffles, and baffle structure on the difference in the MRT for the WSD particles were investigated by applying the proposed model.

Diurnal variations of atmospheric polycyclic aromatic hydrocarbons (PAHs) during three sequent winter haze episodes in Beijing, China

Gas- and particle-phase concentrations of 18 atmospheric polycyclic aromatic hydrocarbons (PAHs) were respectively measured during daytime and nighttime at an urban site of Beijing around the New Year's Day of 2015. The average concentration of total atmospheric PAHs (Σ18PAHs) during three haze episodes (PM2.5>75μg/m3) was 1473.1ng/m3, which was 2.6 times higher than that (405.1ng/m3) during normal periods (PM2.5<75μg/m3). Significant diurnal variations in the Σ18PAH concentrations, homologue pattern and gas–particle partitioning were observed during haze episodes. There was a significantly negative correlation between Σ18PAH concentrations and planetary boundary layer heights. During haze episodes, PAHs in daytime atmosphere should mostly originate from the vehicle emission, while the main sources shift to coal combustion in the nighttime. The gas–particle distribution behavior of PAHs was decisively affected by air temperature and relative humidity, and generally simulated by Junge–Pankow model. During haze episodes, the average benzo[a]pyrene equivalent concentration of atmospheric PAHs in the nighttime were 0.7-fold higher than that in the daytime, indicating that people staying out more during haze episode nighttime would pose a considerably higher cancer risk for inhalation exposure to PAHs.

The effect of rolling amplitude and period on particle distribution behavior in a rolling circulating fluidized bed

The effect of rolling amplitude and rolling period on particle distribution behaviors in a rolling circulating fluidized bed (RCFB) has been quantitatively clarified by means of the electrical capacitance tomography (ECT) technique. A series of experiments with a cold mode RCFB were performed while the rolling amplitude and rolling period varied from Θ=2.5° to 10.0° and T=5.0 to 15.0s, respectively. Based on the particle distribution images captured by the ECT sensor, three main characteristics of particle distribution behavior, namely the average particle volume fraction, the particle distribution stability and the particle distribution uniformity, were quantitatively estimated. As results, the particle distribution behavior in the RCFB was dominated by the shear effect, which was derived from the inertial forces and gravity in the radial direction of the riser. The positive influence of rolling amplitude on the shear effect caused augmentation of the particle volume fraction; however, particle distribution became unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction was dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors was observed due to its minimal influence on the shear effect.

Tuning the Friction Characteristics of Gecko-Inspired Polydimethylsiloxane Micropillar Arrays by Embedding Fe₃O₄ and SiO₂ Particles.

In order to improve stiffness of polydimethylsiloxane (PDMS) pillars while maintaining high friction, the effects of embedding Fe3O4 and SiO2 particles on the friction behavior of PDMS micropillars are studied. Both types of added particles increase the stiffness of the PDMS composite, but affect the friction behavior differently. The frictional force of the fibrillar array fabricated with Fe3O4/PDMS composite decreases initially, then increases as the particle content increases. For silica/PDMS composite pillars, the frictional force is independent of the particle density. Characterization by scanning electron microscopy shows that Fe3O4 particles are distributed uniformly in the PDMS matrix at low concentration, but heterogeneous distribution is observed at high particle loading, with particles being hindered from penetrating into the pillars. For silica/PDMS composite pillars, the particles distribute homogeneously inside the pillars, which is attributed to the formation of hydrogen bonding between silica particles and PDMS. The difference in particle distribution behavior is used to explain the observed difference in the friction response of these two composite systems.

J0510101 プロセス・トモグラフィー法を用いた揺動する循環流動層内の可視化計測と数値計算による評価

Dynamic properties of particle distribution behaviors in the circulating fluidized bed with rolling motion have been clarified by both Electrical Capacitance Tomography (ECT) experiment and CFD-DEM simulation. A series of experimentals with a cold mode the rolling circulating fluidized bed is performed wihle the rolling amplitude and period varies. As a result, the particle distribution behavior at z'=300mm is dominated by the shear effect which is derived from the inertial forces and gravity in the radial direction of riser. Positive influence of rolling amplitude on the shear effect causes augmentation of particle volume fraction, but particle distribution becomes unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction is dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors can be recognized due to its little influence on the shear effect.

F121 CFD-DEMカップリングによる搖動する循環流動層内粒子分布特性の数値解析(OS9 熱・流動(2))

F121 CFD-DEMカップリングによる搖動する循環流動層内粒子分布特性の数値解析(OS9 熱・流動(2))

Parametric CFD studies on hydrocyclone

Abstract This research article encompasses development of hydrocyclone simulation methodology through validation with suitably designed experiments at a range of process conditions and further understanding on the parametric design and operating conditions. The salient features of the methodology included Eulerian primary phase flow field generation through steady state simulation using RSM turbulence modeling, and evaluation of particle distribution behavior through discrete phase modeling using particle injection technique. The results are validated with water throughput, split and cyclone cut size while classifying flyash. The results have indicated a reasonable matching between the simulated and the experimental values. The studies revealed that the cyclone cut size increases with an increase in vortex finder diameter, a decrease in the spigot diameter, decrease in the inlet velocity of the fluid, and decrease in the viscosity of the fluid.

E211 揺動する循環流動層内における触媒粉体濃度分布のキャパシタンスCT計測(OS9 熱・流動(計測・試験))

E211 揺動する循環流動層内における触媒粉体濃度分布のキャパシタンスCT計測(OS9 熱・流動(計測・試験))

Internal distribution of micro-/nano-sized ceramics and metals particles in mice

Internal distribution of several nanoparticles in mice has been investigated using scanning X-ray analytical microscopy, magnetic resonance imaging and inductively coupled plasma–atomic emission spectroscopy. According dynamic laser scattering analysis, the actual particle size of obtained metal oxide was similar to that of metal particles. The estimated diameters were ca. one micrometer. After administration through the tail vein of the mice, metal particles quickly reached some organs. The distribution ratio reached a constant value and was then maintained. On the other hand, the metal oxide particles were first localized in the spleen and lung. The concentration in the lung was decreased with post-injection time. This result suggested that the particles were temporally trapped in the lung then removed to other organs. The behaviors between metal and metal oxide were quite different even when those particles had a similar actual particle size. Therefore, the distribution behavior of particles depended on the chemical species.