Impact Of Particle Size Distribution Research Articles

Impact of Particle Size Distribution for Variable Mixing Time on Mechanical Properties and Microstructural Evaluation of Al-Cu/B4C Composite

Abstract In the present work the combined effects of particle size and distribution on the mechanical properties of the 20vol.% B4C particle reinforced Al–Cu alloy composites by powder metallurgy is investigated. The aim of this work was to evaluate the effect of mixing time (5h, 15h and 25h) and particle size (23µm and 67µm) of B4C particles on the metallurgical and mechanical properties. It has been found that small ratio between matrix/reinforcement particles sizes resulted in more uniform distribution in the matrix. The particles distributed more uniformly in the matrix with increasing in mixing time. The results also showed that homogenous distribution of the B4C particles resulted in higher hardness, ultimate tensile strength, yield strength and elongation. Fracture surface observations showed that the dominant fracture mechanism of the composites with small B4C particle size (23µm) is ductile fracture of the matrix, accompanied by the “pull-out” of the particles from the matrix, which is attributed to positive effect of reinforcement particles in resistance to the movement of dislocations while the dominant fracture mechanism of the composites with large B4C particle size (67µm) is ductile fracture of the matrix, accompanied by the B4C particle fracture

Dynamical and thermal property of rising bubbles in the bubbling fluidized biomass gasifier with wide particle size distribution

In-depth understanding of the dynamical and thermal property of bubbles is required to elucidate the phenomena occurring in a bubbling fluidized gasifier. In this work, numerical simulation is conducted for the biomass gasification in a three-dimensional bubbling fluidized bed through the multiphase particle-in-cell method. After validating the numerical results with experimental data, the impact of particle size distribution of sand material on the dynamical property (i.e., the rising velocity, spatial distribution, volume) combined with the thermal property (i.e., gas species, temperature, pressure, density, thermal conductivity) of the rising bubbles in the system are explored. The results demonstrate that large bubbles have a high mass fraction of combustible gases. Along the bed height, the bubble temperature, specific heat and thermal conductivity continuously increase while the density and pressure decrease. Compared with the boundary, the bubble interior has a higher temperature, smaller density, and more combustible gases. Enlarging the particle size distribution width increases the bubble volume, aspect ratio, mass fraction of combustible gas in the lower part of the bed, temperature and the thermal conductivity of bubbles, but decreases the rising velocity, density and pressure of the rising bubbles. The results obtained provide a new perspective regarding the effect of particle size distribution on the bubble property especially the first report regarding the thermal property of the rising bubbles in the bubbling fluidized gasifier, which will be beneficial for the in-depth understanding for the fundamental aspects and also the practical operation for this kind of apparatus.

Deposition of ambient ultrafine particles in the respiratory tract of children: A novel experimental method and its application

Because of ethical and practical constraints, there are few experimental studies on the deposition of ultrafine particles (<100 nm; UFPs) in the respiratory tract of children. To address this deficiency, we developed a novel method based on a flow-through chamber bag inhalation system, which is capable of measuring in situ size-resolved and total deposition of ambient UFP in a large number of children. The method was validated on four children (aged 9–11 years) at an urban primary school in Brisbane, Australia with breathing frequency ranging from 12 to 28 breaths/min, with repeated measurements conducted for a reference adult on 4 different days to test its repeatability. A stochastic lung deposition model (IDEAL) was used to predict total particle deposition to further asses the performance of the method. The total deposition fraction was 0.59 ± 0.02 (Mean ± SD) in 4 experiments of the reference adult, while it was 0.59 ± 0.13 in 4 children and in good agreement with the model calculated value of 0.57 ± 0.09. The method was repeatable (with precision ranging from 0.01 to 0.06) and sensitive enough to reflect the influence of breathing patterns on size resolve deposition fraction and the impact of particle size distribution on total deposition. Three measurements of size-resolved (10–379 nm) and total deposition fraction can be finished in 15 min (with the exposure time of only half of this), even at concentrations as low as 1.7 × 103 cm−3. We demonstrated that the novel method is capable of providing fast and reliable quantification of size-resolved and total deposition of UFP in respiratory tracts of children and adults.

Mechanotunable Surface Lattice Resonances in the Visible Optical Range by Soft Lithography Templates and Directed Self-Assembly.

We demonstrate a novel colloidal self-assembly approach toward obtaining mechanically tunable, cost-efficient, and low-loss plasmonic nanostructures that show pronounced optical anisotropy upon mechanical deformation. Soft lithography and template-assisted colloidal self-assembly are used to fabricate a stretchable periodic square lattice of gold nanoparticles on macroscopic areas. We stress the impact of particle size distribution on the resulting optical properties. To this end, lattices of narrowly distributed particles (∼2% standard deviation in diameter) are compared with those composed of polydisperse ones (∼14% standard deviation). The enhanced particle quality sharpens the collective surface lattice resonances by 40% to achieve a full width at half-maximum as low as 16 nm. This high optical quality approaches the theoretical limit for this system, as revealed by electromagnetic simulations. One hundred stretching cycles demonstrate a reversible transformation from a square to a rectangular lattice, accompanied by polarization-dependent optical properties. On the basis of these findings we envisage the potential applications as strain sensors and mechanically tunable filters.

Impact of Particle Size Distribution of Colloidal Particles on Contaminant Transport in Porous Media

The presence of retained colloidal particles causes the retardation of contaminant transport when the contaminant is favorably adsorbed to colloidal particles. Although the particle size distribution affects the retention behavior of colloidal particles, the impact of particle size distribution on contaminant transport has not been reported to date. This study investigates the impact of the particle size distribution of the colloidal particles on contaminant transport through numerical simulation by representing the particle size distribution as a lognormal distribution function. In addition, the bed efficiency and contaminant saturation of simulated breakthrough curves were calculated, and a contaminant transport model with the Langmuir isotherm for the reaction between the contaminant–sand and contaminant–colloidal particle was introduced and validated with experimental data. The simulated breakthrough curves, bed efficiency, and contaminant saturation indicated that an increase in the mean and standard deviation of the particle size distribution causes the retardation of contaminant transport.

Impact of Particle-Size Distribution on Flow Properties of a Packed Column

AbstractA karst collapse column (KCC), a type of vertical structure that is common in the Carboniferous-Permian coal fields of North China, contains many graded broken rocks and often functions as ...

Impact of Engineered Filter Bed Substrate Composition and Plants on Stormwater Remediation within a Rain Garden System1

Abstract Thirty-two rain-garden-engineered filter-bed substrates (EFBS) resulting from combinations of two substrate bases (sand and slate), two organic matter amendments [composted yard waste (CYW) and pine bark (PB)], two combination methods (banding and incorporation), and four combination amounts [2.5 cm/5%, 5.1 cm/10%, 7.6 cm/15%, and 10.2 cm/20% (by vol.)] were evaluated using three plant species (Betula nigra L. ‘Duraheat', Monarda fistulosa L. and Panicum virgatum L. ‘Shenandoah'). The impact of particle size distribution, saturated hydraulic conductivity (Ksat), volume of effluent, evapotranspiration, EFBS composition, and plant growth on water movement within a rain garden was determined. Sand EFBS maintained a numerically lower Ksat compared to slate EFBS regardless of composition. Using CYW and banding reduced effluent volume and increased evapotranspiration. Each EFBS was also evaluated for its ability to support plant growth and nutrient uptake. Shoot dry weight and shoot nutrient content (nitrogen and phosphorus) trends were similar and were highest for all species when grown in sand amended with banded CYW. Higher levels of total soluble nitrogen (TSN) were in the effluent from CYW compared to PB, regardless of substrate base. Sand generally had lower concentrations of TSN and PO4−3-P present in the effluent than slate. Index words: bioretention cell; saturated hydraulic conductivity (Ksat); effluent volume; effluent nutrient concentration; evapotranspiration; particle size distribution; total soluble nitrogen; ortho-phosphate; nitrate; ammonium. Species used in this study: ‘Duraheat' river birch (Betula nigra L.); wild bee balm (Monarda fistulosa L.); and ‘Shenandoah' switch grass (Panicum virgatum L.).

Impact of Selected Properties of Raw Material on Quality Features of Granular Fertilizers Obtained from Digestates and ASH Mixtures

Abstract The paper presents the results of research, the objective of which was to determine the impact of particle size distribution and density of digestates and ash on density and tensile strength of granular fertilizer obtained from mixtures of these substrates. Particle size distribution, absolute density, envelope density and porosity of substrates were determined. Granular fertilizers were made of clean substrates and their mixtures. Envelope density of the obtained granulates was within 0.81 - 1.88 g⋅cm-3. The determined compaction degree was within 3.65 - 10.12. While, the compaction index IS of granulates made of mixtures was within 0.5 - 0.55 and was lower in comparison to IS of granulates from digestates (0.6) and ash (0.76).

Simulating the Impact of Particle Size Distribution on the Performance of Graphite Electrodes in Lithium‐Ion Batteries

AbstractIn this work we present a fundamental model‐based analysis of the effect of active material particle size distribution (PSD) on graphite electrodes and their performance. We focused on the determination of the impact of differently shaped and scaled PSDs on the electrode performance, which is mainly influenced by the performance of the individual particles and their interaction. A mathematical electrode model with a distributed particle size is used for analysis to identify the different local current densities and the charging behavior of the particles. The heterogeneity provokes uneven surface overpotentials and reaction rates. Their identification facilitates the investigation of the degradation of such heterogeneous systems. In addition, we present an approach that accounts for the change of a PSD because of the restructuring of the electrode morphology during battery usage into the mathematical model and identify the general impact of particle cracking and agglomeration on the battery performance. Moreover, the importance of PSD in Li‐ion batteries is shown by comparing the results obtained with a single particle model used commonly. This comparison shows that in case of narrow distributions surface‐area‐ and volume‐based mean approximations are sufficient to predict overpotentials and electrode capacity if kinetic losses are dominated either by reaction at the surface or diffusion processes, respectively. This work indicates that the PSD and its change impact the performance and degradation of Li‐ion batteries considerably. We suggest that the PSD and its evolution should be of particular interest in the study of the degradation of particle‐based electrodes.

Optimum particle size distribution design for lost circulation control and wellbore strengthening

In this paper, we have experimentally studied the impact of particle size distribution (PSD) on the fracture sealing capability of lost circulation material (LCM) blends. Our primary aim was to determine the PSD which maximizes the Wellbore Strengthening (WBS) benefits obtained from fracture sealing. High-pressure borehole fracturing experiments were conducted on Berea sandstone samples under atmospheric pore pressure and various confining pressures to investigate the WBS effects of several LCM blends. Post-fracturing methods such as Computerized Axial Tomography (CAT) scan and thin-section imaging were used to investigate the geometry of induced fractures and formed seals within them. Based on the conducted experiments and post-fracturing analyses, we have evaluated and re-assessed well-known theories applicable to the design of LCM blends, such as the one-third rule, the ideal packing theory, and the Vickers criteria. Our experiments indicate that for any rock with a given set of rock strength and failure parameters, there exists an optimum PSD to maximize WBS benefits. Optimum PSD appears to be of primary importance, almost independent of LCM type. In addition, we have shown that the optimum PSD should have a bimodal structure, with sufficient concentrations of properly sized fine and coarse particles. Although the one-third rule, the ideal packing theory, and the Vickers criteria may provide some basic PSD guidelines, these theories are mainly empirical relationships based on conventional particle plugging experiments. As shown here, they do not properly represent the physics of fracture sealing. To remedy this situation, we are introducing a new family of design curves for optimum PSD, based on the underlying physics of fracture sealing observed in the WBS experiments.

Processing and structure–property relationships of natural rubber/wheat bran biocomposites

In this work, wheat bran was used as cellulosic filler in biocomposites based on natural rubber. The impact of wheat bran content [ranging from 10 to 50 parts per hundred rubber (phr)] on processing, structure, dynamic mechanical properties, thermal properties, physico-mechanical properties and morphology of resulting biocomposites was investigated. For better characterization of interfacial interactions between natural rubber and wheat bran, achieved results were compared with properties of biocomposites filled with commercially available cellulosic fillers—wood flour and microcellulose. It was observed that wheat bran, unlike commercial cellulosic fillers, contains high amount of proteins, which act like plasticizers having profitable impact on processing, physical, thermo-mechanical and morphological properties of biocomposites. This is due to better dispersion and distribution of wheat bran particles in natural rubber, which results in reduction of stiffness and porosity of the biocomposites. Regardless of cellulosic filler type, Wolff activity coefficient was positive for all studied biocomposites implying reinforcing effect of the applied fillers, while tensile strength and elongation at break decreased with increasing filler content. This phenomenon is related to restricted strain-induced crystallization of NR matrix due to limited mobility of polymer chains in the biocomposites. Furthermore, this explains negligible impact of particle size distribution, chemical composition and crystallinity degree of applied cellulosic filler on static mechanical properties of highly-filled NR biocomposites. The conducted investigations show that wheat bran presents interesting alternative for commercially available cellulosic fillers and could be successfully applied as a low-cost filler in polymer composites.

Comment on "Attenuation and dispersion of sound in dilute suspensions of spherical particles" [J. Acoust. Soc. Am. 108(1), 126-146 (2000)

Comment is made on an article by Temkin [J. Acoust. Soc. Am. 108(1), 126-146 (2000)]. This work illustrates the impact of particle size distribution on the dispersion and attenuation of sound waves propagating through particle suspensions. Temkin's propagation theory is extended for poly-disperse distributions of spherical particles, applicable to real suspensions. Significant changes in dispersion and attenuation appear near the particle resonance for both bubble and solid particle suspensions. Existing experimental data for bubble distributions also shows a good agreement with the poly-disperse modifications proposed.

Effect of particle size distribution on turbidity under various water quality levels during flocculation processes

The dynamic relationship between particle size distribution and water turbidity was characterized using online real-time monitoring devices to explore the impact of particle size distribution on water quality. Particle amount was proportional to water turbidity in the range of 0–40NTU, whereas the correlation was rather poor in the range of 40–100NTU. The number of particles smaller than 5μm (Nd<5) should be strictly monitored and controlled in water treatment works (WTWs) due to their complex behaviors. The fractal dimension of particles (dpf) is well suited to characterize particle size distribution under different water turbidities. The first derivative of dpf was firstly used to explain the relationship between dpf and the percentage of Nd<5, and the turbidity and dpf values could be used together to monitor the temporal evolution of the number of smaller particles. A new block method for analyzing flocculation processes was proposed based on the change in dpf. The particle counting method was more sensitive to the evolution of particle size, which allowed a better understanding of the impact of particle size distribution on water turbidity.

Particle size dependence of respiratory tract uptake in a population cohort

Background. Sources and exposure levels of fine particles (PM2.5) are well known to vary over different microenvironments. Less investigated is the impact of particle size distribution on the respiratory tract uptake. However, the particle size, ranging from few nanometers to many micrometers, over more than three orders of magnitude, significantly affects the infiltration of ambient particles indoors and the uptake of the particles in the respiratory tract. Aim. The aim of the work is to use realistic spatial and particle size distributions in Helsinki to estimate the contribution of various sources and particle sizes to the human uptakes by respiratory tract regions. Methods. The current work uses the FINRISK-cohort with 5700 subjects in the Helsinki metropolitan area to estimate the exposure levels, infiltration and respiratory tract uptake of the particles. Particle concentrations were estimated for 2010 using CAR-FMI dispersion model. Emission source information was used to estimate lognormal source specific particle size distributions for the tailpipe, coarse and regional background concentrations. Size distributions observed at the Hyytiälä background station were used for the latter; the two other distributions were based on literature and thus contain larger uncertainties. Previously developed and evaluated model was used to estimate the changes in the particle size distributions by infiltration. ICRP 1994 model was then used to estimate the respiratory tract uptakes. Results. Particle mass uptake was dominated by accumulation mode particles in the alveolar region, followed by same particle size range in the bronchiole and then coarse (Dp 1-2.5 µm) particles in the alveolar region. Conclusions. When looking at particle mass, ultrafines do not dominate uptakes even in the alveolar region. Accumulation mode particles have an order of magnitude higher contribution to alveolar uptakes when ignoring times spent in traffic.

Mechanism of the Impact of Particle Size Distribution to Bed-Inventory Overturn for Pant-Leg Circulating Fluidized Bed

An improved two particle sizes numerical model based on a uniform size model was established to investigate the influence of the average particle size on bed-inventory overturn inside a pant-leg circulating fluidized bed (CFB). The new model successfully simulated the dynamic performance of a pant-leg CFB that as average particle size shrank, the pant-leg CFB tended to overturn, while the uniform size model showed a contradicted trend. The success was attributed to the difference of the flow pattern with different particle size. The smaller particles tend to stay the upper furnace after fluidized by the primary air flow while the larger particles tend to fall back to the bottom soon after being carried to upper furnace by the primary air flow and smaller particles. As pointed out in our previous work, the lateral mass transfer resulted in a lateral pressure difference at the upper finance and inhibited further lateral mass transfer, which was regarded as a self-balancing process. The quick fall down of the large particles somehow weaken the lateral pressure different built-up at the upper furnace. Therefore, as the average particle size shrink, the weaken effect of the large particles on self-balancing ability of the pant-leg CFB increase, resulting a more tendency for bed-inventory overturn. It was such a characteristic behavior of the large particles, which was neglected in the uniform particle size model, caused the difference between the results of the two models described above.

Water flow exchange characteristics in coarse granular filter media

Elution of inhibitory metabolites is a key parameter controlling the efficiency of air cleaning bio- and biotrickling filters. To the authors knowledge no studies have yet considered the relationship between specific surface area related elution velocity and physical media characteristics, which constitutes a scientific gap. This study investigates the impact of particle size distribution (considering materials with multiple particle sizes) and irrigation rate on the overall specific surface area related elution velocity distribution in porous granular media. The elution measurements performed in this study are performed at a concurrent airflow of 0.3ms−1, water irrigation rates of 1–21cmh−1 in materials with particle diameters ranging from 2 to 14mm to represent media and operation conditions relevant for low flow biotrickling filter design. Specific surface area related elution velocity distribution was closely related to the filter water content, water irrigation rate, media specific surface area and particle size distribution. A predictive model linking the specific surface area related elution velocity distribution to irrigation rate, specific surface area and particle size distribution was developed and predicted the observed specific surface area related elution velocity distributions with a mean error of 9%.

Study on the impact of particle size distribution on turbidity in water

Abstract To better understand the impact of particle size distribution on water turbidity, a series of flocculation tests were carried out at different slow stirring speeds to produce the experimental data needed. Results were obtained using an online turbidimeter, coupled with an online particle counter, and all the measurements were performed at regular intervals. It was found that within the turbidity range of 0–40 NTU, particle amount increased linearly with increasing turbidity, whereas for the range of 40–100 NTU, particle amount remained almost unchanged and the correlation between particle amount and turbidity became poor, possibly due to the fact that particles in different size ranges contributed differently to the change of turbidity. The results also demonstrated that particles larger than 5 μm were greatly related to water turbidity, but for particles smaller than 5 μm, a poor correlation between the number of particles and turbidity was found. Therefore, the number of particles smaller than 5 μm should be particularly measured and controlled during water treatment processes to produce maximum removal of particles from water. As expected, the particle counter can be used as a useful supplement to the turbidimeter, in order to effectively evaluate water treatment efficiency and ensure water safety.

Relationship between Particle Size Distribution of Low-Rank Pulverized Coal and Power Plant Performance

The impact of particle size distribution (PSD) of pulverized, low rank high volatile content Alaska coal on combustion related power plant performance was studied in a series of field scale tests. Performance was gauged through efficiency (ratio of megawatt generated to energy consumed as coal), emissions (SO2,NOx, CO), and carbon content of ash (fly ash and bottom ash). The study revealed that the tested coal could be burned at a grind as coarse as 50% passing 76 microns, with no deleterious impact on power generation and emissions. The PSD’s tested in this study were in the range of 41 to 81 percent passing 76 microns. There was negligible correlation between PSD and the followings factors: efficiency, SO2,NOx, and CO. Additionally, two tests where stack mercury (Hg) data was collected, did not demonstrate any real difference in Hg emissions with PSD. The results from the field tests positively impacts pulverized coal power plants that burn low rank high volatile content coals (such as Powder River Basin coal). These plants can potentially reduce in-plant load by grinding the coal less (without impacting plant performance on emissions and efficiency) and thereby, increasing their marketability.

Effect of particle size distribution on the hydration and compressive strength development of α-calcium sulfate hemihydrate paste

Particle size distribution (PSD) of α-calcium sulfate hemihydrate (α-HH) was quantitatively analyzed by Rosin–Rammler–Bennett (RRB) distribution function. The hydration of plaster and the compressive strength development of paste were correlated with the RRB parameters, focusing on the singular effect of particle fineness (described by the characteristic particle size, De) and distribution width (described by the uniformity coefficient, n) on the water–hemihydrate weight ratio (W/H) for standard consistency, hydration rate, compressive strength and microstructure of paste. The effect of particle fineness is more pronounced than that of distribution width. The microstructure details are in general agreement with the impact of PSD on the hydration and the compressive strength development of paste. The plaster with the optimum PSD hydrates completely without a hydration barrier at a relatively lower W/H for standard consistency. Then, homogeneous and well-grown calcium sulfate dihydrate (DH) crystals and a more compact structure are obtained, leading to a higher compressive strength. For pastes of standard consistency, an optimum PSD is characterized by De≈35μm and n≈0.82.

Design and Implementation of Retention/Filtration Media for Sand Control

Summary The factors that control the performance of sand-control screens that use woven metal mesh as the filter media (i.e., commonly called premium screens), are not, generally, well understood by the end user. The end user is told that premium sand-control screens use filter media such as Dutch, Dutch Twill, or a Reverse Dutch Twill woven metal mesh, and in some cases the manufacturer will promote the benefit of multiple layers of woven-metal-mesh filter in the screen to control the sand. All this information is interesting, but the end user really does not understand the significance of the information. This paper presents the results of a study to evaluate the effect of different metal-mesh weaves on the performance (e.g., dirt holding capacity, and plugging tendency) of media commonly used in sand-control screens. The work also introduces a new approach to designing sand-control screens that use woven-metal-mesh material. The performance criteria used in the evaluation of different designs for the filter media include the control of solids and the impact of particle size distribution on the formation of plugging on the surface and in the filtration media. Laboratory testing demonstrates that use of a different type of construction of the retention/filtration media allows for greater performance than media currently used in premium sand-control screens. The significance of the approach discussed in this paper is the ability to design and engineer a premium sand-control screen with a retention/filtration medium for a given particle size distribution of the formation that allows for maximum oil production and minimum solids production. Critical to the success of this approach to designing sand-control screens is the thorough evaluation/testing of multiple media types to create the "formation specific" design.