Optical properties of chain-like soot with water coatings
Publication date: Available online 18 July 2019Source: ParticuologyAuthor(s): Meng Fan, Liangfu Chen, Liangxiao Cheng, Benben Xu, Jinhua Tao, Shenshen LiAbstractIn a moist atmosphere, the ageing process of aerosol can make the agglomerated soot particles compact, and cause them to be covered by a water coating. Based on the cluster‒cluster aggregation (CCA) algorithm, the models of chain-like soot with water coatings (Models A to E) were generated in this study. The superposition T-matrix method was employed to calculate their optical properties at 337, 550, 860, and 1060 nm wavelengths, with a focus on the impact of t...
Source: Particuology - July 18, 2019 Category: Science Source Type: research
Two-dimensional densely ordered packings of non-convex bending and assembled rods
We report the two-dimensional dense packing patterns of bending and assembled rods, which are non-convexly deformed from simple objects and modeled as entangled particles. Monte Carlo simulations and further analytical constructions are carried out to explore possible densely packed structures. Two typical densely packed structures of C-bending rods are found, and their packing densities are identified as being functions of the aspect ratio and central angle. Six shapes of assembled rods, representing the combined deformations of rods, are employed in simulations with the packing structures classified into three types. The...
Source: Particuology - July 17, 2019 Category: Science Source Type: research
Eco-friendly method for synthesis of zeolitic imidazolate framework 8 decorated graphene oxide for antibacterial activity enhancement
We report a rapid method for synthesis of zeolitic imidazolate framework 8 (ZIF-8)-decorated graphene oxide (GO) composites (ZGO) with good antibacterial properties. The ZGO composites were synthesized at room temperature with low GO to metal salt ratios. The samples were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis, and surface area analysis. The characterization results show that ZIF-8 with a size of approximately 120 nm is successfully decorated on the surface of GO sheets with the host ZIF-8 framework maintained in the s...
Source: Particuology - July 16, 2019 Category: Science Source Type: research
Estimation of particle depth from two defocused images using the Fourier transform
Publication date: Available online 9 July 2019Source: ParticuologyAuthor(s): Wu Zhou, Xu Luo, Benting Chen, Yukun Zhang, Xiaoshu CaiAbstractDepth from defocus is one technology for depth estimation. We estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging distances. The images are processed with the Fourier transform to obtain the characteristic parameter (i.e., the standard deviation of the relative blur kernel of these two defocused images). First, we theoretically analyze the functional relationship between the object depth and the standard de...
Source: Particuology - July 10, 2019 Category: Science Source Type: research
Exploration of particle technology in fine bubble characterization
This article reviews modern particle characterization technologies, especially those that can be used to characterize fine bubbles, and briefly reports on some applications of fine bubbles.Graphical abstract (Source: Particuology)
Source: Particuology - July 7, 2019 Category: Science Source Type: research
Experimental study and Shannon entropy analysis of pressure fluctuations and flow mode transition in fluidized dense phase pneumatic conveying of fly ash
The objective of this study was to relate experimental pressure fluctuation behavior to the transition in mode of flow observed in fluidized dense phase pneumatic conveying of fly ash. Shannon entropy and wavelet analysis were utilized to extract features of the flow regimes. Daubechies db4 wavelet analysis of pulsating air pressure revealed that the flow mechanism of fly ash in a fluidized dense phase possessed non-steady characteristics associated with gradual aeration of dunes along the direction of flow. Variations of Shannon entropy values along the length of the pipeline were assessed to determine the location at whi...
Source: Particuology - July 3, 2019 Category: Science Source Type: research
Numerical analysis and experimental validation of hydrodynamics of a thin bubbling fluidized bed for various particle-size distributions using a three-dimensional dense discrete phase model
Publication date: Available online 2 July 2019Source: ParticuologyAuthor(s): Abolhasan Hashemisohi, Lijun Wang, Abolghasem Shahbazi, Hossein AminiAbstractA dense discrete phase model combined with the kinetic theory of granular flows was used to study the bubbling characteristics and segregation of poly-dispersed particle mixtures in a thin fluidized bed. Our simulations showed that in using the hybrid Eulerian–Lagrangian method, the common use of one computational cell in the thickness direction of the thin bed does not predict wall friction correctly. Instead, a three-cell discretization of the thickness direction does...
Source: Particuology - July 3, 2019 Category: Science Source Type: research
Three-dimensional multiphase full-loop simulation of directional separation of binary particle mixtures in high-flux coal-direct chemical-looping combustion system
In this study, we developed a three-dimensional Eulerian–Eulerian multiphase full-loop model for simulating the circulation and separation of binary particle mixtures in a novel high-flux CDCLC system. This model comprised a high-flux circulating fluidized bed as the fuel reactor (FR), a counter-flow moving bed as the air reactor (AR), a high-flux carbon stripper, two downcomers, and two J-valves. This model predicted the main features of complex gas–solid flow behaviors in the system. The simulation results showed that quasi-stable solid circulation in the whole system could be achieved, and the FR, AR, and J-valves o...
Source: Particuology - July 3, 2019 Category: Science Source Type: research
Wavelet denoising and nonlinear analysis of solids concentration signal in circulating fluidized bed riser
Publication date: Available online 2 July 2019Source: ParticuologyAuthor(s): Li-Li Gu, Yawen Zhang, Jesse ZhuAbstractParticles, particle aggregates, and reactor walls complicate the dynamic microstructures of circulating fluidized beds (CFBs). Using local solids concentration data from a 10-m-high and 76.2-mm-inner-diameter riser with FCC (Fluid Catalytic Cracking) particles (dp = 67 μm, ρp = 1500 kg/m3), this paper presents an improved denoising process for use before nonlinear chaos analysis. Using the soft-threshold denoising method in the wavelet domain with experimental empty bed signal...
Source: Particuology - July 3, 2019 Category: Science Source Type: research
A computational particle fluid-dynamics simulation of hydrodynamics in a three-dimensional full-loop circulating fluidized bed: Effects of particle-size distribution
Publication date: Available online 2 July 2019Source: ParticuologyAuthor(s): Hang Zhang, Youjun LuAbstractA computational particle fluid-dynamics model coupled with an energy-minimization multi-scale (EMMS) drag model was applied to investigate the influence of particle-size distribution on the hydrodynamics of a three-dimensional full-loop circulating fluidized bed. Different particle systems, including one monodisperse and two polydisperse cases, were investigated. The numerical model was validated by comparing its results with the experimental axial voidage distribution and solid mass flux. The EMMS drag model had a hig...
Source: Particuology - July 3, 2019 Category: Science Source Type: research
Effect of ring baffle configuration in a self-priming venturi scrubber using CFD simulations
This study uses computational fluid dynamics to survey the gas‒liquid flow hydrodynamics of a self-priming venturi scrubber with and without ring baffles. Based on the simulation results, we explore how the structure and configuration parameters such as baffle height, opening-area ratio, and baffle thickness affect the injection flow rate and the homogeneity of the gas‒liquid mixture. In addition, we report the best structure and configuration parameters for the ring baffle. The best position for the ring baffle is at nearly 7/16 of the length of the diffuser above the throat. Having the baffle too near the throat caus...
Source: Particuology - June 30, 2019 Category: Science Source Type: research
Seasonal variations of PM10 — Trace elements, PAHs and Levoglucosan: Rural sugarcane growing area versus coastal urban area in Southeastern Florida, USA. Part II: Elemental concentrations
In this study, PM10 was collected from Belle Glade, close to the sugarcane-growing area, and from Delray Beach, an urbanized area along the East Coast of Florida. The PM samples were analyzed for trace elements and close to organic compounds. To elucidate the importance of preharvest sugarcane biomass smoke emissions on air quality, 39 trace elements, 18 PAHs, and levoglucosan were selected to apportion ambient PM constituents. Al, Ca and to a great extend also Mg are the major soil-related trace elements and key markers for fugitive soil dust emissions. Similarly, sea salt aerosol blown from the Atlantic Ocean into Florid...
Source: Particuology - June 30, 2019 Category: Science Source Type: research
Effects of surface vortex on the drawdown and dispersion of floating particles in stirred tanks
Publication date: Available online 27 June 2019Source: ParticuologyAuthor(s): Wentao Xu, Yangbo Tan, Meng Li, Jianglong Sun, De Xie, Zeng LiuAbstractThe effects of surface vortex on the drawdown and dispersion of floating particles in stirred tanks were investigated. Particle distribution and power consumption were analyzed by experiments and numerical simulations in both baffled and unbaffled tanks agitated by a Rushton impeller. In unbaffled tanks, a non-aggregation rule was applied and the average dispersion index was found to serve as a reasonable prediction of the full drawdown of floating particles. The critical impe...
Source: Particuology - June 28, 2019 Category: Science Source Type: research
Discrete element method study of effects of the impeller configuration and operating conditions on particle mixing in a cylindrical mixer
Publication date: Available online 26 June 2019Source: ParticuologyAuthor(s): Yuyun Bao, Tianchi Li, Dengfei Wang, Ziqi Cai, Zhengming GaoAbstractWe employed the discrete element method to study the effects of the impeller configuration (i.e., blade diameter, inclination angle, and blade number), rotational speed, and fill level on the flow and mixing of particles in a cylindrical mixer equipped with flat and inclined blades. The coefficient of rolling friction, coefficient of static friction, and coefficient of restitution were experimentally determined before the simulation, and simulation results of the torque and surfa...
Source: Particuology - June 27, 2019 Category: Science Source Type: research
Controlled TiO2 coating on hollow glass microspheres and their reflective thermal insulation properties
Publication date: Available online 26 June 2019Source: ParticuologyAuthor(s): Jie Long, Chongwen Jiang, Jundong Zhu, Quzhi Song, Jiang HuAbstractHollow glass microspheres (HGMs) have great potential in building energy-saving and industrial insulation. Anatase TiO2-modified HGMs were prepared by a sol‒gel method in acetic acid-ethanol solution. Scanning electron microscopy, X-ray diffraction, zeta-potential measurements, nitrogen-sorption measurements, and Fourier-transform infrared and ultraviolet-visible-near-infrared diffuse reflectance spectroscopies showed that the alkali modification of the HGMs greatly influenced t...
Source: Particuology - June 27, 2019 Category: Science Source Type: research
