Effect Of Particle Size Distribution Research Articles

Effect of particle size distribution on the thermal conductivity of crushed GMZ bentonite pellet mixtures

Effect of particle size distribution on the thermal conductivity of crushed GMZ bentonite pellet mixtures

The effect of particle size distribution on the collapse of wet polydisperse granular materials

Low-saturation liquid-containing granular materials are commonly encountered in both natural and industrial settings, where interstitial liquids significantly affect the motion of particles, while particle size polydispersity plays a crucial role in determining the level of system cohesion. In this study, the collapse of wet polydisperse granular columns is numerically investigated based on the developed discrete element model, with corresponding dam-break experiments performed to validate our numerical model and methodology. The dependence of the dynamics and flow mobility on particle size distribution is primarily examined, and the underlying mechanisms are also explored by analyzing particle path lengths and average fidelity. Building upon the effective Bond number proposed using the mixing theory, a macroscopic cohesion parameter at the material scale is defined by considering the dependence of the collapse on the system size effect. The relevance of this cohesion parameter in describing different wet polydisperse granular collapses is further validated based on our designed experimental tests and DEM simulations. The approach of constructing the cohesion parameters at different scales can be extended to characterize cohesion effects in more complex wet polydisperse granular flows and describe their associated rheological behaviors.

Numerical study of a chemical looping combustion system: Effects of fuel type and particle size distributions on the operating performance

Chemical looping combustion (CLC) using biomass offers a promising pathway for achieving negative carbon emissions. However, the different properties of coal and biomass affect reaction performance, which has not been fully explored in the CLC system. Additionally, the effects of particle size distributions (PSDs) of solid fuels and oxygen carriers (OCs) are inadequately addressed. In this study, a 3D reactive model using the computational particle fluid dynamics (CPFD) method is developed to investigate the effects of PSDs of both solid fuels and oxygen carriers on operating performance with coal and biomass as fuels. Results indicate that the average residence time in FR of coal and biomass particles is 0.86 s and 0.68 s, respectively, but biomass outperforms coal in reaction efficiency. For coal-fueled CLC, the average residence time is 0.46 s for coal particles with diameters of 100–200 μm, whereas it reaches 0.86 s for coal diameters of 300–700 μm. However, the reaction performance is better with smaller coal sizes due to char gasification being the rate-limiting step. In comparison, for biomass-fueled CLC, the reaction efficiency remains consistent across various particle sizes under the specified conditions due to the rapid release of volatile components and the low content of char. Additionally, it is found that the OC conversion ratio is mainly determined by their residence time in the zones with relatively higher concentrations of the combustible gas in FR. Employing OCs with overly wide PSDs such as 300–800 μm can compromise the material seal above the AR, increase the risk of gas leakage and decrease the separation efficiency of the inertial separator.

Effect of particle size distribution and content of limestone powder on compressive response of high-early-strength cement mortars

This study examined the effect of particle size distribution and content of limestone powder on the compressive response of high-early-strength portland cement mortars cured either in water or under ambient conditions. Nineteen mortar mixtures were classified into three groups based on the particle size distribution of the pulverized limestone powders: L (blaine = 3467 cm2/g), M (blaine = 4710 cm2/g), and H (blaine = 5764 cm2/g). The design equations for the compressive strength gain rates and stress–strain relationship of ordinary portland cement (OPC) concrete were adapted for the present mortars. The test results revealed that the 28-d compressive strength (fc′) of the mortars tended to decrease with an increase in limestone powder content, even for mortars containing 5 % limestone powder with small particle sizes. This contrasts with the common trend of the positive effect of limestone powder on the compressive strength of OPC concrete up to a certain substitution level. Furthermore, mortars containing finer limestone powders exhibited a greater rate of decrease in fc′, regardless of the curing conditions. The modified equations show promise for reliably assessing both the compressive strength gain rates at different ages and the stress–strain behavior of high-early-strength portland cement mortars containing limestone powders.

Interparticle interaction effect on superparamagnetic properties of ferrimagnetic particles

Uncoated and oleic acid coated ferrimagnetic particles are synthesized. Both samples contain similar magnetite particles. Structural characterization of these particles is performed using x-ray diffraction, Fourier transform infrared spectra, dynamic light scattering, transmission electron microscopy and thermogravimetric analysis. Average crystallite size of magnetite is 7 nm. Thickness of oleic acid layer on each magnetite particle is 1 nm. The oleic acid coated sample contains 23% oleic acid. Temperature dependence of the zero field cooled and field cooled susceptibility of the uncoated magnetite particles peaks at 120 K and both the curves bifurcate at 195 K. The peak temperature and the bifurcation temperature of the system decrease due to the oleic acid coating. The inverse susceptibility does not vary linearly with temperature in high temperature region. Magnetization versus applied magnetic field data at 250 K are analyzed in three different ways to study the interparticle interaction and the particle size distribution effects on magnetization. We find that the both factors affect the magnetization process of ferrimagnetic nanoparticles.

Effects of Powder Reuse and Particle Size Distribution on Structural Integrity of Ti-6Al-4V Processed via Laser Beam Directed Energy Deposition

In metal additive manufacturing, reusing collected powder from previous builds is a standard practice driven by the substantial cost of metal powder. This approach not only reduces material expenses but also contributes to sustainability by minimizing waste. Despite its benefits, powder reuse introduces challenges related to maintaining the structural integrity of the components, making it a critical area of ongoing research and innovation. The reuse process can significantly alter powder characteristics, including flowability, size distribution, and chemical composition, subsequently affecting the microstructures and mechanical properties of the final components. Achieving repeatable and consistent printing outcomes requires powder particles to maintain specific and consistent physical and chemical properties. Variations in powder characteristics can lead to inconsistencies in the microstructural features of printed components and the formation of process-induced defects, compromising the quality and reliability of the final products. Thus, optimizing the powder recovery and reuse methodology is essential to ensure that cost reduction and sustainability benefits do not compromise product quality and reliability. This study investigated the impact of powder reuse and particle size distribution on the microstructural and mechanical properties of Ti-6Al-4V specimens fabricated using a laser beam directed energy deposition technique. Detailed evaluations were conducted on reused powders with two different size distributions, which were compared with their virgin counterparts. Microstructural features and process-induced defects were examined using scanning electron microscopy and X-ray computed tomography. The findings reveal significant alterations in the elemental composition of reused powder, with distinct trends observed for small and large particles. Additionally, powder reuse substantially influenced the formation of process-induced defects and, consequently, the fatigue performance of the components.

Optimization of non-spherical particle flow in vertical waste heat recovery devices: Analyzing structural configurations

Vertical waste heat recovery devices are emerging but are immature. The vertical waste heat recovery devices of circular, square, and optimized designs were analyzed for a full capacity of 8 tons of sintered ore. Using DEM theory, the effects of particle size distribution, velocity, and wall forces on void fraction distribution and particle flow were examined. The circular device demonstrated superior mixed particle flow compared to the square device, achieving integrated flow for 50 % of particles in the cone, in contrast to 26 % for the square device. An optimized circular device achieved integral flow for 90 % of particles, significantly enhancing overall flow and reducing wall adhesion, attributed to its improved internal design. Through insert and distributor design, the overall particle flow within the device improved, with almost no particles remaining on the walls. These findings underscore the potential for enhanced heat recovery efficiency through optimized internal structures in waste heat recovery devices.

An experimental and theoretical study on effects of particle size distribution on flowability and film properties of organic powder coatings

An experimental and theoretical study on effects of particle size distribution on flowability and film properties of organic powder coatings

Interfacial performance evolution of ceramics-in-polymer composite electrolyte in solid-state lithium metal batteries

The incorporation of ceramics into polymers, forming solid composite electrolytes (SCEs) leads to enhanced electrical performance of all-solid-state lithium metal batteries. This is because the dispersed ceramics particles increase the ionic conductivity, while the polymer matrix leads to better contact performance between the electrolyte and the electrode. In this study, we present a model, based on Hybrid Elements Methods, for the time-dependent Li metal and SCE rough interface mechanics, taking into account for the oxide (ceramics) inclusions (using the Equivalent Inclusion method), and the viscoelasticity of the matrix. We study the effect of LLTO particle size, weight concentration, and spatial distribution on the interface mechanical and electrical response. Moreover, considering the viscoelastic spectrum of a real PEO matrix, under a given stack pressure, we investigate the evolution over time of the mechanical and electrical performance of the interface. The presented theoretical/numerical model might be pivotal in tailoring the development of advanced solid state batteries with superior performance; indeed, we found that conditions in the SCE mixture which optimize both the contact resistivity and the interface stability in time.

Particle size distribution effects on the light scattering properties in non-diluted colloidal suspensions: A numerical study

The static light scattering technique potentially offers a nondestructive evaluation of a particle size distribution in dense colloidal suspensions. Understanding the size distribution’s correlation with the light scattering properties and modeling electromagnetic scattering with high accuracy and efficiency are crucial for technique development. The polydisperse dependent scattering theory (DST) is an accurate model, but its calculation is costly. We aim to numerically examine the size distribution effects on the scattering properties of dense suspensions up to the volume fraction of 20% in the near-infrared wavelength of 600–1000 nm using three electromagnetic models: the polydisperse and monodisperse DST, and the local monodisperse approximation (LMA). We considered various size distributions in Gaussian and logarithmic forms with constant standard deviations of 21 nm and 101 nm in the mean diameter range of 75–700 nm by shifting the distribution while keeping its shape. We showed that the monodisperse approximation is invalid at a small mean diameter of less than 200 nm, even at the sharp Gaussian distribution. It suggests the strong size distribution effects. Meanwhile, the approximation holds at a large diameter of more than 650 nm, even at the broad logarithmic distribution. We showed that the LMA results nicely agree with the polydisperse DST results for all the current conditions. At the same time, the LMA calculations are over a thousand times faster than the polydisperse DST because the LMA reduces the sum calculation over particle diameter pairs. Thus, the LMA is a great candidate for the electromagnetic model.

Effect of particle size distribution on the dewatering circuit design; case study: iron ore tailing of the Gol-E-Gohar mining and industrial company

ABSTRACT Iron ore processing plants of the Gol-E-Gohar mining and industrial company have three thickeners. The thickeners’ underflow's is pumped to a tailings dam, with the solid content of about 50%. To increase water recovery, this research investigated the effect of the particle size distribution on the dewatering circuit design of tailings. Physical and chemical characteristics of the thickeners’ underflows (solid content, XRF, XRD, density, etc.) are determined and three different dewatering circuit designs considered. In the first design, only a pressure filter was considered for each stream separately, and in the second design, all streams were combined, and then particles coarser than 1 mm were removed using the screen and dewatered by a pressure filter. In addition, in the third design, all streams are combined and particles coarser than 250 microns are removed using hydrocyclone-screen. Particles smaller than 250 microns are dewatered using a pressure filter. The results showed that the required filtration area (m2) related to the dewatering circuits to reach 20% moisture of plants’ tailings are 1074, 926, and 912 m2, respectively. Finally, it is determined that because of the positive impact of coarse particles on the filtration performance and the operational problems related to the particles larger than 1 mm, all streams must be combined and dewatered using a pressure filter.

CFD-DEM investigation of centrifugal slurry pump with polydisperse particle feeds

Polydisperse particle feed into centrifugal slurry complicates hydraulic performance and wall erosion but is poorly understood. This paper presents a numerical study of a centrifugal slurry pump, focusing on the effect of particle size distribution (PSD) using the combined computational fluid dynamics and discrete element method (CFD-DEM). It incorporates rigid impeller rotation and wall erosion. On this basis, the hydraulic and erosion model validity is verified by clear water performance and jet erosion test, respectively. Additionally, this CFD-DEM model is compared with the dense discrete phase model (DDPM), demonstrating more precise erosion prediction as its fully resolved particle-particle interactions. Generally, total pump erosion severity intensifies when the PSD is broadened. Compartment-wise, it indicates the necessity of tailoring flow structure to enlarge drag force, therefore, mitigate particle aggregation in the impeller. This in-house CFD-DEM model is promising for addressing particle-fluid flow problems in centrifugal pumps or coupling with data driven method.

Feasibility analysis of the Sanchez-Pomraning method to treat the particle size distribution in particle-dispersed fuel

The non-uniform size of particles appears in the particle-dispersed fuel generally, but this phenomenon is usually neglected. This study aims to evaluate the feasibility of the Sanchez-Pomraning method to solve the particle size distribution problem in particle-dispersed fuel. The Pu-rich agglomerate phenomenon in the MOX fuel and manufacturing tolerance in the Fully Ceramic Microencapsulated (FCM) fuel are calculated by ALPHA-DH code, which implements the Sanchez-Pomraning method based on the MOC transport calculation and improved subgroup resonance calculation. Numerical results show that the Sanchez-Pomraning method has the capability to treat the particle size distribution effect accurately, where the differences between the Sanchez-Pomraning method and the Monte Carlo method are generally lower than 160 pcm. For the Pu-rich agglomerate phenomenon, the results show that ignoring the Pu-rich agglomerate effect introduces the reactivity difference of around 600 pcm, and ignoring the size distribution of the Pu agglomerate will cause the reactivity of up to 200 pcm in the extra-high or extra-low Pu enrichment. The more discrete size distribution and the smaller Pu-spots, the more significant influence will occur in the MOX fuel. For the FCM fuel, the influence brought by the TRISO particle size distribution can be ignored when only TRISO particles are filled. However, ignoring the size distribution when TRISO particles and poison particles are both added into the FCM fuel introduces the differences reaching 600–1000 pcm. These results demonstrate the importance of considering the particle size distribution for analyzing the MOX fuel and FCM fuel in practice. And the Sanchez-Pomraning method is reliable to analyze the effect of particle size distribution.

Investigation of Particle Gradation Effect on Soil-Rock Mixture Using Direct Shear Test

Soil-rock mixture (SRM) is a special geomaterial that is composed of soil and a certain percentage of rock blocks with various sizes and strengths. It has high structural strength and renewable resources that are used as filler in subgrade, construction material and embankment dams. However, the mechanical properties of the soil-rock mixture are sophisticated owing to the complicated interaction between soil and rock particles. Previously, many experimental investigations were conducted to focus on shear behaviours and the influencing factors of SRM. Yet, limited w ork has been done to underline the effect of particle size distribution towards SRM shear strength parameters. Thus, this study conducted an SRM shear test with three different kinds of gradation and rock block percentages. Various soil densities, porosities and different framework structures have resulted from different rock particle concentrations. From the results, the well-graded SRM shows a non-linear trend of cohesion value while uniformly graded and gap-graded SRMs shows contradicting trend respectively. The result and analysis in this study are especially useful in analysing its influence on the shear strength parameters of SRM with different rock block percentages.

Phase compositions, microstructures, and microwave dielectric properties of novel high-entropy spinel-structured MAl2O4 ceramics

High-entropy design for MgAl2O4 spinel has rarely been reported. In this study, six novel high-entropy spinel-structured (HES) MAl2O4 ceramics were prepared through the conventional solid-state reaction method. The effect of high-entropy design on the crystal structure, microscopic morphology, and microwave dielectric performance of HES ceramics was investigated based on X-ray diffraction (XRD), Raman spectra, and scanning/transmission electron microscopy (SEM/TEM). The analysis shows that the difference of one element among the high-entropy components can lead to an obvious variation in the lattice parameters, microstructures, and performance. The differences in microstructure, especially grain size, are the joint effects of particle size distribution, porosity, and composition. Specifically, (Mg0.2Mn0.2Co0.2Ni0.2Zn0.2)Al2O4 (HES04) ceramic sintered at 1625 °C for 4 h exhibits superior properties: εr=8.78 ± 0.03, Q×f=34,022 ± 910 GHz (@12.62 GHz), and τf=−29.3 ± 0.6 ppm/°C. These results suggest that the high-entropy strategy is an effective method to tune the dielectric properties of MgAl2O4 ceramic.

Preparation of good fluidity coal water paste based on the modified compartment stacking theory

ABSTRACT Coal water paste (CWP) is a mixture of pulverized coal and water with a mass concentration of more than 70 wt%. CWP has a higher coal concentration than traditional coal water slurry (~60 wt%), so it can significantly improve the efficiency of gasification and combustion. However, the preparation and rheology of paste is extremely complicated due to its high concentration and material complexity. In this paper, to obtain the preparation method of CWP which could meet the engineering demands, the effects of coal particle size distribution, grading ratio, and type and amount of dispersant on rheology of CWP are investigated. Based on the modified compartment stacking theory, the improved preparation method of CWP has been proposed, which introduces the influence of coarse particle shape. The particle size ratio of coarse and fine particles is about 12, the particle size ratio of fine and ultra-fine particles is about 5, the optimal three-peak grading ratio is 6:1:3. The preferred dispersant is pure naphthalene dry powder (PNDP), and its addition amount is 1.4 wt%. The flow grade of CWP (71 wt%) could reach A without any other modifications or treatments.

Influence of powder particle size distribution on the creep performance of Ti-48Al-2Cr-2Nb alloy fabricated via electron beam-powder bed fusion

The effects of particle size distributions (PSDs) on the microstructure and creep behavior of Ti-48Al-2Cr-2 Nb fabricated via electron beam-powder bed fusion (EB-PBF) were investigated. Three PSDs of 45–150 (PSD-A), 38–150 (PSD-B), and 38–180 µm (PSD-C) were used as powder feedstock. Widening the PSD range decreased the relative density of fabricated parts and promoted the formation of banding microstructure. Moreover, samples fabricated with wider PSDs had a higher volume of lack-of-fusion (LoF) defects; however, the content of gas pores decreased significantly in PSD-C, which was related to the presence of coarse powder particles. The volume of the LoF defects in PSD-C was approximately 2.8 times of the same defects in PSD-A, which influenced the creep performance (at 750℃) and failure mechanism of Ti-48Al-2Cr-2 Nb. A longer steady-state creep period at different stress levels was identified for the samples fabricated with the narrowest PSD (45–150 µm). Widening the PSD span also caused weakness in the creep properties and data scattering at higher stress levels of 300 and 350 MPa. The LoF defects and coarse grains accelerated the crack initiation and propagation in Ti-48Al-2Cr-2 Nb during creep. This study represents the first report on the impact of PSD on the creep properties of TiAl alloys fabricated via EB-PBF, which offers new insights and enhances understanding of the powder-process-microstructure-property relationship.

Effect of particle size distribution on the properties of celsian based glazes

AbstractThe microstructure and surface properties of ceramic glaze are influenced by chemical composition, particle size distribution, glaze application conditions, and firing parameters. This study specifically focused on the influence of glaze particle size distribution on the thermal behavior, microstructure, and surface appearance of barium frit based ceramic glaze in the floor tile firing process. The investigation involved examining the impact of four distinct particle size dimensions (d50: 5.7 μm, 6.8 μm, 7.5 μm, 10.9 μm) on the glaze properties by using hot stage microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), color and gloss measurements. The studies indicated that celsian is the dominant phase in the glaze structure. The sintering and softening temperatures of glazes decreased with the increase of milling time. A decrease in the particle size of the glaze slurry increased the whiteness index. As the average particle size (d50) of the glaze decreased, the number of crystals was also increased. The investigation results also suggested a relation between specular reflection and milling time. As the milling time extended, there was a corresponding increase in the magnitude of glossiness.

Aerosol Deposition of CuFeO2 Photocathode Coatings for Hydrogen Production

AbstractPhotoelectrochemical (PEC) water splitting is a viable route for green hydrogen generation. In PEC cells, the electrodes are coated with suitable semiconductor materials, which absorb the sunlight, generating charge carriers that are used to split water molecules into H2 and O2. CuFeO2 is one promising photocathode material for water splitting. However, its performance is limited by electron/hole pairs recombination within the film and at the film/substrate interface. Aerosol deposition (AD) can be employed to minimize charge recombination by spraying dense, thin films and by establishing a good back-contact interface. In this study, CuFeO2 powders were synthesized through a conventional solid-state technique and sprayed by AD under varied parameter sets. The effect of particle size distributions, carrier gas, gas pressure and substrate temperature was investigated. The best spraying parameter set was then tuned to obtain thin coatings (< 1 µm). Single-particle deformation and coatings microstructure were investigated by scanning electron microscopy. Optical properties of CuFeO2 films were analyzed by UV–Vis spectroscopy, while photoelectrochemical performances were estimated through amperometry tests under simulated sunlight. The results of this research show that CuFeO2 photocathodes can be successfully manufactured by AD. Their performance can be optimized by adjusting coating thickness and by annealing in air.

Effect of particle size distribution of sediments on development of polder soils in Japan

Abstract Purpose Polder soils develop from oceanic and lacustrine sediments covered with seawater, brackish water, and freshwater after artificial drainage. Because there are several concerns regarding the agricultural use of polder soils, soil genesis and properties have been considerably surveyed, mainly focusing on problematic soils developed from fine sediments. Although sediments have a wide range of particle size distributions due to different sedimentary conditions, particle size of parent materials have not been well addressed to understand the soil developmental process. In this study, Japanese polders with different reclamation ages and sedimentary conditions were surveyed to clarify the soil formation process and factors affecting pedogenesis. Materials and methods Soil samples were collected from 15 soil profiles in six Japanese polders under different land use types. Sedimentary conditions of polders were evaluated from particle size distributions using the hydrodynamic classification proposed by Pejrup (The triangular diagram used for classification of estuarine sediments: a new approach. Tide-influenced Sediment Environ Facies, pp 289–300, 1988). The major soil-forming factors of polders were extracted by principal component analysis (PCA) using general soil properties. Results and discussion Brackish lake and inner bay polders were characterized by calm hydrodynamic conditions comprising fine particles. Two polders reclaimed from a shallow inland sea were characterized by violent hydrodynamic conditions. Sandy sediments were also characteristic of immature soils reclaimed from a freshwater lake and an estuarine tidal flat. Soils on polders developed under calm hydrodynamic conditions enabled the accumulation of high total carbon content. The soil-forming process in the brackish bay oxidized pyrite, leading to an acidic soil reaction. Conversely, soils developed from sandy sediments were characterized by low iron content. The PCA extracted two factors explained by particle size and soil reaction relating to acidification and salt leaching. Conclusion Polder soils can be mainly discriminated by their particle size distributions, which are characterized by hydrodynamics under the sedimentary conditions, and the polder soil development is affected by water management in land uses after artificial drainage.