Particuology最新文献

In seed breeding, the vibrating screen used for pre-sowing grading parental seeds often has the problem of poor self-purification rate. Using elastic balls to clean the plugging seeds and ensure the self-purification of the screen is a viable technical solution. To clarify and improve the operating performance of the elastic ball particles, a DEM-MBD coupling simulation model of the elastic ball screen-cleaning device was established in this study, and a numerical simulation analysis of the complex motion process was carried out. The mechanism of action of the elastic ball was explained more completely from the aspects of excitation force and energy transfer. Through the Plackett-Burman test, it was determined that the vibration frequency has the most significant effect on the excitation force. Multiple linear regression analysis was performed on each factor and the mathematical relationship equation. It was found that when the maximum excitation force was greater than 7 N and the average excitation force was greater than 2 N, the self-purification rate was greater than 95%. The self-purification rate was then increased to 99.81% by variable frequency tests. The variable frequency achieved better self-purification effect.

Fluidization technology has been used in CO₂ capture processes, the successful design and operation of the heat exchangers involved in this process require much information on the bed-to-wall heat transfer of the sorbent particles in fluidized states. In this study, the bed-to-wall heat transfer coefficient (h) of a solid amine sorbent was measured by a heat transfer probe in a large-scale circulating fluidized bed cold model unit, where full spectrum of fluidization regimes can be realized. The corresponding hydrodynamic signals were also studied by pressure sensors and optical fiber probes to further explain the newly discovered phenomenon. The results show that in a dense bed, due to the counterbalanced effect of time fraction of packet and packet renewal frequency, h of the Geldart B particle reaches a peak within the bubbling fluidized regime, and the radial distribution of h are opposite in bubbling and turbulent fluidized regimes. In a fast fluidization regime, gas convection becomes the dominant factor affecting h when the solids holdup is low enough. Correlations were provided or recommended to guide the design of heat exchangers in the fluidized bed CO₂ capture processes.

For all-solid-state lithium batteries (ASSLBs), polymer-blended solid composite electrolytes (SCEs) have drawn wide interest owing to their significance in improving the interfacial solid-solid contacts and inhibiting the growth of lithium dendrites. In this work, SCEs based on PVDF-HFP/PMMA matrix containing MOFs (NH₂-MIL-53(Al)) and LiTFSI were designed and synthesized employing an easy solution casting method. The synthesized samples were examined by XRD, SEM, EDS, and electrochemical tests. It was found that MPP-2 SCE not only has excellent ionic conductivity at 60 °C of 5.54 × 10⁻⁴ S cm⁻¹, but also exhibits superior interfacial compatibility in Li||Li symmetric batteries, which can constantly cycle for about 800 h at 0.1 mA cm⁻² with no short-circuiting. The assembled Li|MPP-2|LiFePO₄ cell exhibited a first discharge specific capacity of up to 157.1 mAh g⁻¹ at 60 °C and 0.2 C. This work may help to further advance the progress of ASSLBs in the future.

Powder bed fusion methods of additive manufacturing (AM) require consistent, reproducible, and uniform layers of powder for the reliable production of high-quality parts, where properties of powder are central to achieving this. Among these properties, powder flowability and spreadability play critical roles in determining the quality of these powder layers.

While extensive research has been conducted on powder flow and spreading behaviour, and on their characterisation, there is little critical comparison and review of these terms in the context of AM. Such a review is necessary to further develop and enhance our comprehension of spreading dynamics and its relation to powder properties in AM systems.

This review paper aims to build a coherent understanding of the correlation between powder characteristics and spreading in powder based additive manufacturing and its impact on manufactured parts. It highlights the current progress in comprehending spreading dynamics, the influence of powder characteristics, environmental conditions, spreading system, and the development of testing tools to assess powder spreadability. Furthermore, the paper critically discusses the challenge of finding appropriate quantitative metrics and recent advances in the use of standardised methods for evaluating powder spreadability.

The strategic selection of appropriate preparation methods and binder strategies is crucial for enhancing the particle and combustion performance of pyrotechnic delay compositions (PDCs). This study, utilizing droplet microfluidics technology (DMT) and micron-scale raw materials, prepared spherical B/Pb₃O₄ composite particles with varying concentrations of fluorine rubber (F₂₆₀₄). The morphology, specific surface area, bulk density, flowability, friction sensitivity, thermal decomposition, and combustion performance of these microspheres were characterized. The results indicate that as the binder content increases, the particle size of the microspheres first decreases and then increases, the specific surface area decreases, and the bulk density increases, correlating with tighter binding of the reactant powders by the binder. Furthermore, tighter powder-to-powder binding results in a progressive decrease in the thermal decomposition peak temperature of the samples (from 404.2 °C to 346.4 °C). Additionally, increased binder content reduces the friction sensitivity and combustion rate of the samples, which is attributed to the energy absorption properties of the binder. Compared to the control group, the microsphere samples exhibit significantly enhanced bulk density, flowability, friction safety, and combustion delay precision, potentially improving the reliability of PDCs in ignition sequences.

Highly active and cost-effective oxygen evolution reaction electrocatalysts have become essential to replace commercial electrocatalysts that rely on rare noble metals. High-entropy sulfide nanomaterials, characterized by abundant randomly distributed elements and inherent stability, possess significant potential for applications. However, challenges such as uneven composition, partial oxidation, or imprecise synthesis control still remain in the materials preparation. Herein, a simple and effective two-step hydrothermal method was employed to synthesize NiCoFeCuS nanoparticles supported on foam nickel substrate. With the catalytic active sites produced by electron density redistribution in high-entropy and sulfurization, NiCoFeCuS exhibits excellent alkaline OER performance, with an overpotential of 261 mV and a Tafel slope of 57.97 mV dec⁻¹ at the current density of 10 mA cm⁻², which is only 88% of commercial RuO₂ without any noble metals.

In the staged multi-cluster fracturing of shale gas horizontal wells, ball sealers are used to ensure uniform fluid distribution among clusters, a strategy that is both cost-effective and operationally beneficial. Despite these advantages, comprehending the ball sealers' dynamics within the wellbore and their plugging behavior at perforations is still challenging. This complexity results in prediction difficulties regarding their diversion efficiency. To address this, our study utilized a semi-resolved CFD-DEM model based on kernel approximation to simulate the behavior of medium-sized ball sealers in single and multiple cluster scenarios. Our findings from a single cluster scenario reveal that the plugging probability is co-determined by velocity gradients in the fluid ingestion area near the perforation, backflow region, and inertial forces of the ball sealers. As the critical flow rate is achieved, the plugging probability negatively correlated with fluid viscosity and displacement, and positively correlated with the perforation flow ratio (PFR), the difference in particle-fluid density, ball sealer’s diameter, and the ball sealer’s offset from the pipeline center. Temporary plugging control efficiency was used to evaluate the flow balance effect among multiple clusters. The results indicate that an increased number of ball sealers enhances the fault tolerance during the temporary plugging process. Nevertheless, excessive ball sealers might undermine the temporary plugging control efficiency, as perforations with lower fluid inflow rates are unexpectedly plugging. Higher differences in fluid injection rates between clusters led to increased efficiency in temporary plugging control. Premature deployment of ball sealers cannot effectively plug perforations with marginally higher fluid inflow rates, but instead accidently plug intermediate clusters with lower fluid inflow rates. These findings offer a theoretical basis for optimizing the design of ball sealers.

The aim of this study is to investigate the influence of the angle of the pulverized coal (PC) injection lance on the combustion characteristics of fuel in the raceway of blast furnace tuyeres. Using FLUENT software, a Euler-Lagrange three-dimensional numerical model was constructed to analyze the influence of different positions of blast furnace tuyere coal powder injection lance (coaxial and cross-axis) on key parameters such as temperature distribution, gas flow, and combustion efficiency. The results demonstrate that adjusting the angle of the injection lance significantly modifies the average and peak temperatures in the raceway, while the composition of gas components remains relatively stable. When the injection lance angle is 10°, the average temperature and peak temperature in the raceway are 2294 K and 2747 K, respectively. When the injection lance angle is 12°, the combustion efficiency of the PC reaches 80.8%. This study reveals the significant impact of the injection lance angle on the combustion process. Especially at an angle of 12°, the combustion efficiency of the blast furnace significantly improves. With coaxial injection, the combustion rate increases as the distance between the injection lance tip and the tuyere increases. This paper is instructive for the optimization of the blast furnace combustion system, which improve fuel utilization efficiency and reduce environmental emissions. This paper provides practical recommendations for adjusting blast furnace operational parameters, offering insights for achieving more efficient and environmentally friendly industrial production.

The suspension state of crystals in the crystallizer is one of the important indicators for evaluating the adaptability of the crystallizer. This study adopted the Euler-Eulerian two-fluid model to simulate and analyze the fluid motion of solid-liquid two-phase flow in the industrial-grade DTB crystallization kettle, as well as the phase suspension distribution of crystal particles. The main influencing factors investigated are: the heat transfer effect, the height of the bottom of the crystallizer, the number and position of the stirring paddle, crystal size and crystal volume fraction. Based on the research of Euler-Eulerian method to simulate fluids, the Euler-Lagrangian method was further used to simulate the motion state of particle phases with different particle sizes in the crystallizer. It was found that the designed DTB crystallizer has good recycle mixing effect. The particles can be mixed evenly during the operation, which can fully realize the solid-liquid mixing and suspension effect of the drug under study.

Boron nanoparticles, with their remarkably high gravimetric and volumetric calorific values, emerge as the most promising fuel in energetic fields. However, challenges such as susceptibility to oxidation, high ignition temperature, and low combustion efficiency have constrained their further applications. In this study, we fabricated high explosives based nano-boron microspheres with uniform size using the electrostatic spray method, in which the boron nanoparticles and high explosives (CL-20 or PETN) are closely bonded together by fluorinated polymer (F₂₆₀₂) and evenly distributed. The results indicated that the microspheres exhibited high sphericity and showed an enhanced antioxidant capability. The addition of high-energy explosives not only reduced the thermal oxidation temperature of nano-boron powder within the microspheres but also significantly enhanced the pressurization rate. Additionally, the microspheres with added high-energy explosives released more energy during the combustion process. Compared to physically mixed samples, electrostatically sprayed microspheres with a uniform microstructure still exhibited higher reactivity. Therefore, the design and synthesis of microspheres with controllable structures using the electrostatic spray method show promising application prospects.