Effect Of Particle Size Distribution Research Articles

Effect of Particle Size Distribution on Kinetics and Overall Degradation in Anaerobic Digestion of Waste Biomass

Particle size distribution in pre-treated organic substrates significantly impacts microbial fermentation efficiency, with smaller particles offering greater specific surface area, potentially reducing retention times and operational costs, particularly beneficial for remote and urban areas. Laboratory tests compared manual chopping, shredding, grinding, and mincing techniques, finding manual methods more effective than shredders at pretreatment level 1. Non-treated tomato waste showed the highest fine particle distribution (41%), contrasting with grass waste (< 2.9 mm), banana peel waste (< 2 mm), and paper waste (< 3 mm). Combining mincing, grinding, and extended processing increased methane output, particularly evident in higher pre-treatment levels with enhanced surface area. Among substrates, banana peel waste biomass (BPWSB) yielded the most methane (332 ± 36 Nml/gVS, 67% VSR), while grass waste biomass (GWSB) in semi-continuous tests produced 253 ± 29 Nml/gVS. The Biochemical Methane Potential (BMP) kinetic models consistently favored first-order kinetics over the modified Gompertz model across all substrates, attributing higher k-values to PTL4 due to its large surface area: BPWSB (0.59), GWSB (0.339), PWSB (0.59), and TWSB (0.59). These findings emphasized slower decay of larger particles and more rapid degradation of smaller fractions, crucial for optimizing biogas production efficiencies.

Investigating the effect of particle size distribution and complex exchange dynamics on NMR spectra of ions diffusing in disordered porous carbons through a mesoscopic model.

Ion adsorption and dynamics in porous carbons are crucial for many technologies, such as energy storage and desalination. Nuclear magnetic resonance (NMR) spectroscopy is a key method to investigate such systems thanks to the possibility of distinguishing adsorbed (in-pore) and bulk (ex-pore) species in the spectra. However, the large variety of magnetic environments experienced by the ions adsorbed in the particles and the existence of dynamic exchange between the inside of the particles and the bulk renders the interpretation of the NMR experiments very complex. In this work, we optimise and apply a mesoscopic model to simulate NMR spectra of ions in systems where carbon particles of different sizes can be considered. We demonstrate that even for monodisperse systems, complex NMR spectra, with broad and narrow peaks, can be observed. We then show that the inclusion of polydispersity is essential to recover some experimentally observed features, such as the co-existence of peaks assigned to in-pore, exchange and bulk species. Indeed, the variety of exchange rates between in-pore and ex-pore environments, present in experiments but not taken into account in analytical models, is necessary to reproduce the complexity of experimental NMR spectra.

Carrier-phase DNS study of particle size distribution effects on iron particle ignition in a turbulent mixing layer

The ignition and combustion of iron particles in a turbulent mixing layer is studied by means of three-dimensional carrier-phase direct numerical simulations (CP-DNS). A particular focus is set on particle size distribution (PSD) effects on the ignition behaviour by comparing CP-DNS results from using a realistic experimental PSD to DNS data based on a monodisperse (MD) particle cloud with the same equivalence ratio. The CP-DNS solves the Eulerian transport equations of the reacting gas phase and resolves all turbulent scales, while the particle boundary layers are modelled in the Lagrangian point-particle framework. A previously validated sub-model for the oxidation of iron to Wüstite (FeO) that accounts for both diffusion- and kinetically-limited combustion is employed. The mixing layer is initialised with an upper stream of air carrying cold iron particles and an opposed lower stream of hot air. Simulation results show distinct differences in the ignition behaviour between the MD and PSD cases. The ignition of the PSD case is delayed compared to the MD case and does not show any significant particle clustering prior to ignition. Further investigations indicate that the particle size has a crucial effect on the mixing process and ignition time. Small particles start their oxidation process early and already consume some of the available oxygen, while not crucially affecting the gas temperature due to their limited iron mass contribution. Conversely, a slower entrainment into the lower stream combined with higher thermal inertia and the prior oxygen depletion by the small particles leads to a delayed oxidation of the larger particles. As a net result, the PSD case shows a wide spread of individual particle ignition delay times and overall delayed bulk ignition compared to the MD case, where the majority of the particles ignites over a shorter period of time.

Effects of residual effective stress and particle size distribution on reconsolidation characteristics of granular materials after undrained cyclic shear: a 3D DEM study

Effects of residual effective stress and particle size distribution on reconsolidation characteristics of granular materials after undrained cyclic shear: a 3D DEM study

Simplified DEM-Based Modelling and Simulation of the Track Ballast

This study proposes a rational method for modelling ballast in tracks based on the discrete element method (DEM) approach. To simulate a ballast consisting of a group of gravels, it is essential to use the discrete element method. The ballast comprises randomly arranged gravels of unspecified shapes, and requires multiple steps and a separate house code for implementing the ballast. In this study, a simplified ballast analysis model using the parallel bond method (PBM) is proposed and verified through comparison with design standards. Additionally, case studies are conducted to investigate the effect of particle size distribution and micromechanical parameters on the simulation results.

Study on reactivity characteristic of TDA droplet group with gaseous phosgene for preparing TDI

Toluene diisocyanate stands as a pivotal chemical, predominantly synthesized through the phosgenation reaction between toluene diamine and phosgene. To address the inherent limitations of existing phosgenation methods, we pioneered a novel phosgenation reaction based on flash atomization and confirmed its feasibility with preliminary theoretical calculations. This manuscript delves deeper into the superiority of this method and refines its reaction parameters. By integrating the discrete phase model with the Eulerian model, we studied the reaction dynamics of droplet sprays, exploring the effects of spray velocity, droplet size, phosgene temperature, and particle size distribution on the reaction. Our results highlight that, with a mean droplet diameter of 70 μm and a spray velocity of 40 m/s, an impressive reaction yield of 97.4 % can be achieved. This research enriches our understanding of the gas–liquid two-phase phosgenation method, setting the stage for its future exploration and potential applications in Toluene diisocyanate and other isocyanate industry.

Design method of high transport performance biochar-cement based materials based on particle size distribution and permeation probability calculation model

Cement-based materials are the most widely used and largest quantity of engineering materials. Enhancing carbon fixation efficiency and reducing carbon emissions in cement-based materials is an active method of coping with climate change, which has important environmental and social benefits. The amount of carbon dioxide transported into the cement-based material represents the maximum carbon fixation capacity. Enhancing the carbon transport performance of cement-based materials is the material guarantee and basic premise for improving their carbon fixation levels. Considering the impact of particle connections on the maximum cluster, a permeation probability calculation model of porous media system was established, providing the changing rule of the permeation probability with the mathematical expectation of the Poisson distribution, which was verified to be reasonable through experimental studies. The experimental results showed that under the same cement-based conditions, the water transport properties of biochar cement-based materials increased as the mathematical expectation increased. The carbon dioxide transport properties were influenced by the surface area of the biochar particles and exhibited a trend of first decreasing and then increasing with an increase in the mathematical expectation. When the water-cement ratio decreased, the differences in the microstructure of cement-based materials with different biochar particle size distributions increased, the change rate of permeation probability therefore was more sensitive, resulting that the differential effects of different particle size distributions on the transport properties were amplified, and the influence of the particle size distribution of biochar on the transport properties of cement-based materials was more significant.

Effect of Particle Factors on the Reflux and Blockage of a Deep‐Sea Six‐Stage Pump Based on CFD‐DEM

AbstractThe deep‐sea six‐stage centrifugal pump is an essential power source of the lifting system that conveys slurry containing coarse particles. Emergency failure of the electric system can easily lead to pump blockage because of slurry reflux. The reflux movement of particles in a six‐stage pump under emergency power failure is investigated using the verified computation fluid dynamics and discrete element method (CFD‐DEM) simulation. The JKR contact model is used to perform particle simulation. Simultaneously, shaped particles are added to realistically simulate the reflux characteristics under deep‐sea mining conditions. The effect of particle size, shape, and size distribution in the reflux is investigated. The blockage behavior of the particles during reflux and the blockage mechanism is clarified. Particles with less shape and size below 30 mm are more conducive to safe slurry transportation. The experimental results verify the credibility of the CFD‐DEM simulation results.

Combined effect of particle size distribution and cationic –anionic mixture surfactant on high ash coal water slurry

With the shortage of petroleum products and the depletion of the oil layer, the most significant scientific challenge is to use fuel most economically. Due to easy availability and low cost, more than decades of coal has been used in India for power generation in power plants. As CWS (coal-water slurry) has been accepted in many industries due to its low cost, easy handling, and low emission, still more research is needed to be done to work with multimodal high ash coal and simultaneously to save energy (like pumping power and to enhance the combustion temperature). In this experiment, the effect of high ash content coal in multimodal coal water slurry with additives and without additives and particle size distribution, shear rate, and shear stress on the rheological behavior of CWS has been investigated. By suitable combination, adding fine coal particles with the coarser, different samples were prepared and found that coal concentration of 67 % by weight having a viscosity within permissible value and after mixing with additives concentration of 50 % of CTAB (Cetyltrimethyl ammonium bromide) and SDC (Sodium di-dodecyl sulphate) the apparent viscosity reduces to the minimum value. Adding more CTAB in the slurry will increase the viscosity, and in the presence of these additives, the stability of MSA-1 is 18 days at a weight concentration of 67 %, meaning the slurry will work for 18 days. Significantly less work has been done in high-ash coal with multimodal samples. Here, an attempt has been made with this high ash multimodal sample along with the combination of mixture surfactant to achieve high concentration with less viscosity.

Effect of particle size distribution and printing parameters on alumina ceramics prepared by Additive Manufacturing

Vat photopolymerization-based additive manufacturing is a promising technology for the preparation of ceramic parts, owing to its short fabrication cycle and low manufacturing cost. However, its application is limited due to the low mechanical properties and deformation of ceramic parts. To improve the properties of ceramic parts, changing particle size and printing parameters have been found to be useful. Herein, alumina ceramic parts were prepared using three different powders with different particle size (Powder A: D50 = 1.3 μm, D90 = 6.1 μm; Powder B: D50 = 3.4 μm, D90 = 10.0 μm; Powder C: D50 = 1.3 μm, D90 = 2.8 μm), different layer thickness (50 μm, 75 μm, 100 μm), and different curing times (1 s, 3 s, 5 s, 8 s). The ceramics prepared with Powder A and Powder C, which possessed the same D50, had almost the same flexural strength, indicating that the flexural strength is closely related to the particle size and its distribution. With the increase in layer thickness, the flexural strength was increased. When the layer thickness was 100 μm, the flexural strength reached 18.5 MPa when samples were prepared with Powder A and Powder C. At the same time, the flexural strength firstly increased and subsequently decreased with increasing curing time. Based on the flexural strength and shrinkage of the sintered ceramics, using Powder A, layer thickness of 50 μm, and curing time of 5 s were regarded as the best fabrication conditions. The results indicate that adjusting powder particle size distribution, layer thickness, and curing time are promising methods for the fabrication of 3D printed ceramics with optimized properties.

Effect of Particle Size Distributions on the Amino Acid Composition and In-vitro Protein Digestibility of Two Varieties of Bean

The study examined the alterations in the proximate composition, in-vitro protein digestibility and amino acid composition of two varieties of bean with respect to particle size distributions. Brown and white beans were processed and milled to obtain flour samples of fine particles. The flour samples were subjected to particle size analyses using Endecott sieve with pore sizes of 300, 315, 500 and 600 µm. The bean flours with different particle sizes were evaluated for proximate composition, protein digestibility and amino acid composition. The results showed that the highest yields obtained for the brown and white flours were 40 % (315 micron) and 35 % (600-micron) respectively. The ash, protein and fibre contents of the samples varied between 4.51 to 4.61 % and 3.72 to 3.78 %; 24.74 to 24.87% and 22.76 to 22.95 %; 3.24 to 5.23 % and 2.11 to 5.15 % for brown and white bean varieties respectively. The highest values for the protein digestibility were obtained in 315µ for both the brown and white bean flours. The results also showed that the amino acid composition of the samples varied with respect to the particle size and the variety of bean flour. The study concluded that particle size of flour should be considered as a quality factor of flours to enhance derivation of nutritional benefits of flours.

Effects of phase ratios, density and particle shapes on directional thermal conductivity of vegetable concrete: A predictive model

This work is devoted to the thermal conductivity of vegetable concrete (Lime-hemp concrete). Various parameters were investigated using a design of experiment : 5 categories of particle size, 3 binder/particle ratios (1, 1.5 and 2) and 3 target densities (300, 400 and 500 kg m−3). The thermal conductivity was measured in steady-state across and along particles. The results clearly depict the effect of direction on thermal conductivity, but prove that density alone is not a good predictor. As an innovative outcome, the porosity was proved to be a good indicator of the respective weights of the parallel and serial conductivity. This is explained by the negative effect of porosity on the connectivity of the binder, which was confirmed by CT scans. The effect of particle size distribution remains weak, except for the category Small, which has also the lowest elongation and for which the conductivity is nearly isotropic. General expressions are proposed to predict the conductivity from the characteristics of vegetable concretes (proportions, densities and conductivities of the gas, particle and binder phases).

Fabrication and characterization of SiC/Al composites prepared by laser powder bed fusion (LPBF) combined with vacuum pressure infiltration

A novel method has been developed to fabricate SiC/Al composites by the combination of laser powder bed fusion (LPBF) and vacuum-pressure infiltration. The effects of the SiC particle size distribution and pre-oxidation on the microstructure and properties of SiC/Al composites were investigated. A new phenomenon of severe lamellar cracking was observed in SiC/Al composites without pre-oxidation treatment, which can be explained in terms of the mechanism of interlayer bonding. The results showed that the residual porosity of the sample without pre-oxidation treatment s was higher than 3 %, with a maximum of (8.16±0.57) %, which was much higher than that of the pre-oxidised samples(1 % – 2%). The bulk density of the powders was significantly improved by designing the material system with mono-, bi-, and tri-modal particle size distributions and the density of final SiC/Al samples gradually increases from 2.804±0.009 to 2.871±0.008 g/cm3, and the volume fraction of SiC increases from 36.7 vol% to 50.1 vol%. As a result, the coefficients of thermal expansion (CTE) of SiC/Al composites varies consistently with the volume fraction of SiC, decreasing from 13.72 to 10.84×10−6 °C−1. Our study shows that this method has the potential for great applications.

Optimization of briquetting conditions and influencing factors of high-strength sludge briquette

With the increase of sewage sludge production in China, there is an urgent need for a clean and efficient sludge treatment, and the coupling utilization of sludge and coal to produce briquette is a potential sludge treatment method. In this work, sludge (with blending ratio higher than 40 wt%, dry basis) and one Chinese low-rank pulverized coal were used as raw materials to prepare sludge briquette by cold pressing method without binder. The effect of sludge moisture content (SMC), briquetting load (BL), blending ratio (BR), and particle size distribution of coal (PSD) on the compressive strength of the briquette were explored. Through FTIR, contact angle, Zeta potential, and SEM analysis, the briquetting mechanism of sludge briquette was clarified. The response surface method (RSM) was used to optimize the briquetting process conditions. The results showed that the order of influence of various factors on the compressive strength of the briquette is as follows: BL > PSD > SMC > BR. The results also showed that the interaction among SMC, BL, and PSD is the main factor affecting the compressive strength of sludge briquette. According to regression analysis, the optimum briquetting conditions are SMC of 14.11%, BL of 46.54 MPa, the weight proportion of sludge of 60%, and the weight proportion of R1 in coal of 52.68%. The quadratic regression model was established by RSM, and the predicted value is close to the experimental value.

Effects of particle shape, physical properties and particle size distribution on the small-strain stiffness of granular materials: A DEM study

The effects of particle shape (angularity α and sphericity S), physical properties (shear modulus Gp and Poisson’s ratio νp) and particle size distribution (uniformity coefficient Cu) on the small-strain stiffness Gmax were investigated via the discrete element method (DEM) in this study. The Gmax values were obtained by DEM simulations of drained triaxial tests. Microscopic analysis indicates that Gmax uniquely depends on two microscale variants, i.e., the mechanical coordination number CNm and contact stiffness between particles. The particle shape effect was only related to CNm. The contact stiffness can be represented by the values of Gp and Cu. Accordingly, an empirical expression composed of CNm, Gp and Cu that can predict the Gmax of granular materials with different particle properties (e.g., particle size distribution, particle shape, and fabric effect) was proposed. The accuracy of the expression has been verified by comparing the data with previous studies.

Effect of particle size distribution on microstructure and chloride permeability of blended cement with supplementary cementitious materials

Abstract In order to improve the chloride ion penetration resistance of supplementary cementitious materials (SCMs) in blended cement, this study optimizes the particle size distribution of cementitious components based on the Fuller model. Portland cement (PC), fly ash (FA), and ground granulated blast furnace slag (GGBFS) are successfully divided into four particle size ranges by precision air classifier, which are 0–8, 8–30, 30–50, and 50–80 μm, respectively. The optimum cementitious materials in four ranges based on 28-day compressive strength are determined by nine groups of orthogonal tests. The blended cement with optimal performance is obtained by GGBFS in 0–8 μm, PC in 8–30 μm, GGBFS in 30–50 μm, and FA in 50–80 μm. The results show that the blended cement with SCMs based on Fuller model have superior microstructure and chloride ion penetration resistance, which is due to their smaller pore size, a strong volcanic ash effect, and chloride ion binding ability. In addition, this research presents a novel approach for realizing the application of a large amount of SCMs in blended cement.

Microscopic mechanical analysis of K0 of granular soils with particle size distribution and rolling resistance effects

Microscopic mechanical analysis of K0 of granular soils with particle size distribution and rolling resistance effects

Straw Inputs Improve Soil Hydrophobicity and Enhance Organic Carbon Mineralization

The mechanism of the influence of soil water repellency (SWR) and agglomeration stability on soil organic carbon (SOC) mineralization has not been thoroughly studied following different methods of returning straw to the field. The research background in this study was ordinary black soil, and the addition of straw was accomplished via straw mixing (CT), straw mulching (CM), straw deep burying (CD), and straw tripling deep burial (CE). A 120-day long-term incubation test was used to measure the contact angle between water droplets and soil, the particle size distribution of aggregates and their organic carbon (OC) content, organic carbon pool (OCP) content, OC contribution, and soil CO2-C release, the extent of SWR and the direct effect of agglomerates on SOC mineralization were assessed under different straw return methods. The results revealed that the water-droplet–soil contact angle (CA) was much greater and the rate of CA decline was significantly lower in the CD treatment compared to the CT, CM, and CE treatments, the rate of water droplet penetration on the soil surface was slower, and the SWR was improved. The CD treatment significantly increased the content of macroaggregates and their OCP content, and also significantly increased the content of microaggregates’ OC. The CO2-C emission rate and cumulative emissions were enhanced by adding the same amount of straw, with the most significant enhancement in the deep straw treatment. The cumulative CO2-C emission rate and SOC mineralization significantly increased with increases in SWR, macroaggregates content, and microaggregates OC content, but significantly decreased with increases in macroaggregates’ OC content, according to principal component analysis and Pearson’s correlation analysis. These results highlight the extent of SWR and the direct effect of agglomerate particle size distribution and OC content on SOC mineralization under different straw return methods. This will help to consolidate soil structural stability and nutrient management to support productivity and SOC sequestration in different agricultural systems.

The response of organic carbon fractions in sediment to rainfall characteristics and slope lengths: Based on four-years on-site monitoring data

The effect of soil erosion processes on the properties of sediment and organic carbon fractions is not well understood under complex erosion environments, such as various rainfall characteristics and transport distances, which leads to a gap in knowledge regarding the role of soil erosion in the global carbon cycle. This study investigated the impact of different rainfall characteristics (patterns and parameters) and slope lengths (5 m ∼ 20 m) on the sediment yield, particle size distribution (PSD) and properties of organic carbon fractions on China’s Loess Plateau. The results show that runoff was highest under rainfall pattern A (extreme rainfall), while the sediment concentration peaked under rainfall pattern B (heavy rainfall), with significant correlation with slope length, rainfall intensity, kinetic energy, rainfall erosivity and precipitation (p less than 0.05). Silt- and clay-sized fractions were transported as primary particles and enriched under rainfall patterns B and C with no differences between slope lengths. The enrichment ratio (ER) of sediment, effective and ultimate particles were primarily influenced by rainfall intensity-related parameters. In contrast, the aggregation ratio (AR) tended to be influenced by rainfall kinetic energy. The content and loss of organic carbon fractions correlated to rainfall parameters and slope length, although no significant difference was observed between different rainfall patterns and slope lengths. Lost organic carbon fractions were predominantly Mineral-associated organic carbon (MOC), with great enrichment under rainfall pattern C and rapid depletion as the slope length increased. Structural equation models (SEM) indicated the effect of rainfall characteristics and slope length on organic carbon loss was mainly due to the regulation of soil loss and particle size distribution of sediment in selective transport erosion processes. We highlighted the need to consider the effect of soil erosion and particle size distribution comprehensively on the carbon cycle from the perspective of organic carbon fractions to describe the potential effects of soil erosion on the carbon budget quantitatively, especially in complex environmental conditions with consideration of scale effect.

Effect of particle size distribution on the laminar flame speed of iron aerosols

Iron particles in air burn in heterogeneous combustion mode and the flame speed is very sensitive to particle size. Previous numerical work on the propagation of flames in iron dust was based on average particle sizes. However, in practice, experiments are conducted with particle size distributions (PSD). This makes it challenging to compare different experiments as the samples used in those studies vary (the average particle size might be similar but not the particle size distribution). It is the aim of the current work to provide insight into the effect of particle size distribution on flame propagation. This involves identifying the minimum number of discrete averaged particle sizes (bins) required in the simulations to capture the burning characteristics of the PSD. Then, flame speed and flame structure for a narrow and broad distribution are investigated. It is shown that the equivalence ratio at which the maximum flame speed occurs for certain mean particle sizes varies with the width of the particle size distribution. The difference in the flame speed between the same average particle size but different standard deviation varies as a function of β (ratio between standard deviation and average particle size), not just the average particle size itself. For a constant β at a particular equivalence ratio, the difference in the flame speed between PSD and mono-dispersed aerosols is approximately the same irrespective of the particle size. The effects of the smaller and bigger particles in the PSD on the flame speed and flame structure are also systematically investigated. The findings in this study confirm that the particle width of the PSD plays a crucial role and that experiments and simulations can not be readily compared if different PSDs are used.