Powder Technology最新文献

{"title":"The effect of cavity shape on critical high-temperature regions formation pattern and structural evolution difference in explosive particle bed","authors":"","doi":"10.1016/j.powtec.2024.120301","DOIUrl":"10.1016/j.powtec.2024.120301","url":null,"abstract":"<div><div>The occurrence of critical high-temperature regions within explosives is a crucial factor in initiating combustion and explosion. The primary causes of hot regions in cavity-containing explosives are dissipative processes occurring inside the explosive or at its interface, such as shear, friction, viscosity, plasticity, and heat transfer. Currently, there is limited research on the generation and dissipation mechanisms of critical high-temperature regions in cavity-containing explosives during impacts, based on the mesoscale analysis that describes particle motion. In this study, a model based on the discrete element method is employed allowing for an accurate analysis of the dynamic and thermodynamic processes among particles, which systematically considers the shear history between particles, elastoplastic collisions, and heat transfer between particles. The temporal evolution of particle temperature and dissipated work contours during the impact process of explosives with different cavity shapes is analyzed. Explosives with cavities undergo three stages during the impact process: the formation of the trapezoidal high-temperature region, cavity collapse, and dispersion of the particle bed, ultimately leading to the formation of two main critical high-temperature regions: near the cavity and near the wall. The temperature rise of hot particles near the wall can be roughly divided into two stages, and the temperature rise mechanisms are different. Initially, the temperature rise is primarily attributed to plastic dissipation of hot particles, and the same initial impact velocity results in the same temperature rise. During the cavity collapsing, continuous momentum transfer occurs between the hot particles near the wall and the particles in the high-temperature shear bands, deeply influencing the development of the high-temperature shear bands through the movement of the hot particles near the cavity. Therefore, the different collapse modes of hot particles near cavities of different shapes lead to differences in the later temperature evolution of the hot particles near the wall. The unique aggregation processes of hot particles near cavities of various shapes result in distinct high-temperature region morphologies: circular cavity exhibits approximate “——” shape, triangular cavity displays arch shape, and inverted triangular cavity presents “M” shape. Significantly, a new mechanism resulting from the interaction of two opposing “jet “flows for the formation of higher-temperature hot regions near the circular cavity has been discovered.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and optimization of volute directing plate and stubble board for enhancing liquidity and anticlogging of tillering straw in spreading operation","authors":"","doi":"10.1016/j.powtec.2024.120288","DOIUrl":"10.1016/j.powtec.2024.120288","url":null,"abstract":"<div><div>In this paper, a novel volute linear directing plate and inverted “Y” structure stubble board are first designed to address the problem of straw agglomeration. Then a flexible and breakable discrete element model of tillering straw is proposed, and a discrete element coupling model of flexible tillering straw-crushing and strip-laying device is also constructed. The results show that the model can predict the operation performance of the crushing and strip-laying more accurately. Finally, the effect of spindle speed, directing plate radius and stubble board angle are investigated in-depth. In addition, the structure optimization of the directing plate and stubble board is conducted by response surface method, and the corresponding field test is also conducted. It is demonstrated that the coefficient of seed zone cleaning increased by 4.6 %, and the coefficient of straw ridge disturbance decreased by 34.6 %, meanwhile, the device performance is greatly improved after optimization.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantification of the hetero-contact formation process for a CuO/CeO2 hetero-aggregate model system prepared by double flame spray pyrolysis","authors":"","doi":"10.1016/j.powtec.2024.120305","DOIUrl":"10.1016/j.powtec.2024.120305","url":null,"abstract":"<div><div>In hetero-aggregates, different materials form sintered hetero-contacts, which lead to new material properties. In this study, the influence of process parameters on the formation of hetero-contacts in Double Flame Spray Pyrolysis (DFSP) was quantified. The mixing of jets was monitored by Particle Image Velocimetry (PIV) measurements as well as by thermocouples and compared to the single flame setting. Overlap of the jets was evaluated using tracers to visualize the mixing zone. Ten CuO/CeO₂ model material samples were prepared with different flame inclination angles, nozzle distances and different particle volume fractions. Mixing on hetero-aggregate level was quantified using Convolutional Neural Network (CNN) evaluations of STEM images, Temperature-Programmed Reduction (TPR) and Differential Centrifugal Sedimentation (DCS) disk centrifugation to determine cluster sizes and hetero-coordination numbers as mixing quantifiers. Here, good correlations between the differently measured quantifiers were observed.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD-based redesign of large industrial-scale cyclones","authors":"","doi":"10.1016/j.powtec.2024.120306","DOIUrl":"10.1016/j.powtec.2024.120306","url":null,"abstract":"<div><div>Cyclones represent a cost-effective solution employed for the separation of particles in gas-solid streams, wherein the enhancement of performance relies on the careful balance between pressure drop and collection efficiency. This study employs Computational Fluid Dynamics (CFD) techniques to numerically assess a large-scale first stage cyclone within a cement kiln cyclone tower. Investigating its reported low collection efficiency, we analyze the impact of geometric modifications aimed at enhancing cyclone performance. The introduction of a dipleg proves to be particularly effective, leading to a substantial increase in collection efficiency and a reduction in pressure drop. The most favorable cyclone configuration demonstrates a remarkable 6 % improvement in collection efficiency and a decrease in pressure drop of approximately 1 mbar. Consequently, particle emissions from the first-stage cyclone are reduced by approximately 30 %, while an increase in clinker production by approximately 100 tons per day is achieved. These findings showcase the potential for significant operational and environmental benefits through optimized cyclone design in cement manufacturing processes.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319872","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significant size change during bacterial cellulose capsule drying","authors":"","doi":"10.1016/j.powtec.2024.120275","DOIUrl":"10.1016/j.powtec.2024.120275","url":null,"abstract":"<div><div>Use of engineered powders, whether by manufacturers or consumers, often requires rapid hydration but is hindered if hydration rates exceed dispersion rates, leading to “fish eyes”. More work is needed to understand how powder could be engineered to actively contribute to its own dispersion while minimizing the use of additional materials and additives. A recently developed bacterial cellulose microcapsule matrix, with good mechanical integrity but minimal mass usage, exhibits remarkable deformability owing to its fibrous shell structure. When dried into powder, the cellulose microcapsules experience significant deformation of their fibrous shells, changing their diameter by orders of magnitude. We demonstrate a capsule shape recovery mechanism by coating the cellulose fibers, which damps fiber interactions. The results demonstrate that drying microfibrous cellulose microcapsules can expand the range of encapsulation modes available and greatly reduce the mass needed to provide efficient powder rehydration.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The mechanism of nanocopper synthesis under supercritical water gasification of methanol","authors":"","doi":"10.1016/j.powtec.2024.120304","DOIUrl":"10.1016/j.powtec.2024.120304","url":null,"abstract":"<div><div>This paper studied the effect of diverse parameters (reaction time, precursor concentration and molar ratio of alkali to copper ions) on different sizes of copper particles production. In all experiments, over 99 % of Cu²⁺ is converted to Cu. The results show that under conditions of shorter reaction time (5 min), lower precursor concentration (0.01 M), and ideal molar ratio of alkali to copper ions ([OH⁻]:[Cu²⁺] = 1), copper nanoparticles are produced with good dispersity, and an average diameter of 33.05 ± 9.34 nm. The study proposes a mechanism that involves organic adsorption on the surfaces of copper nuclei. This implies that promoting ligand adsorption on copper nuclei surfaces is key to producing smaller particles, since it limits nanoparticle growth. Furthermore, H₂ and CO both contribute to the reduction of Cu²⁺ to Cu. H₂ serves as the primary reducing agent, from the analysis of gaseous products. The study proposes a mechanism for nanocopper size control.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142312040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A hierarchical linked cell method based on scale-proportional multi-level DEM grids","authors":"","doi":"10.1016/j.powtec.2024.120296","DOIUrl":"10.1016/j.powtec.2024.120296","url":null,"abstract":"<div><p>The linked cell method is widely used in the discrete element method (DEM) to detect contact between particles because of its high efficiency for uniform particles. However, the efficiency is reduced for polydisperse particles which are common in nature and engineering applications and have a wide size range. In this paper, a hierarchical linked cell method based on scale-proportional multi-level DEM grids is developed to improve the efficiency for polydisperse particles. The performance of the hierarchical linked cell method is verified by simulating different polydisperse particles. The results show that the hierarchical linked cell method can significantly reduce the elapsed CPU time of contact detection in all simulated cases. The scale proportion and the number of levels of the DEM grids are found to be two important parameters influencing the efficiency improvement. The elapsed CPU time decreases as the scale proportion decreases or as the number of levels increases. For a given scale proportion, the optimal number of levels to achieve maximum efficiency should satisfy two conditions: (1) the grid cell granularity is less than 10; (2) the exponential decrease of the grid cell granularity with the number of levels is broken.</p></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CFD-DEM modeling for optimized liquid distribution in fluidized bed spray granulation","authors":"","doi":"10.1016/j.powtec.2024.120299","DOIUrl":"10.1016/j.powtec.2024.120299","url":null,"abstract":"<div><div>In this work, CFD-DEM simulations of two different fluidized bed granulator geometries were performed, aiming to provide an insight into how the injected liquid behaves within the particle bed and thus an overall better understanding of the granulation process itself. Simulation results were evaluated regarding the fate of sprayed droplets, e.g. deposition on a particle, elutriation from fluidized bed, or collision with apparatus walls. For the deposited droplets, the particle–droplet collisions were tracked in order to obtain a locally resolved deposition rate. Spray parameters as well as geometric specifications of the nozzle setup were varied, investigating a broad range of different process conditions. By optimizing apparatus design, especially the air inlet, an even distribution of the liquid droplets within the fluidized bed and overall higher deposition rate can be achieved and a stable steady state with a well-defined spray zone is reached within a broad range of varied spray parameters.</div></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142326587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on the influencing factors of particles jetting behavior in train sanding adhesion enhancement","authors":"","doi":"10.1016/j.powtec.2024.120302","DOIUrl":"10.1016/j.powtec.2024.120302","url":null,"abstract":"<div><p>Sanding is the most widely used adhesion enhancing measure for trains. However, the motion of adhesion enhancement particles is vulnerable to interference from complex operating environment resulting in reduced efficiency. This work focused on the effect of sanding device parameters (sand delivery hose, air pressure and sand-blasting gun) on particles jetting behavior and particles utilization rate based on the train sanding process simulation detecting equipment. Results show that the particles utilization rate gradually improves with jetting velocity increasing and diffusion angle decreasing. Jetting velocity increases with the increase in the air pressure, nozzle diameter of sand-blasting gun and installation angle of sand delivery hose. While jetting diffusion angle decreases with the increase in the delivery hose diameter and outlet diameter of sand-blasting gun. Sanding flow rate is susceptible to the air pressure. The regression models of influencing factors on particles jetting behavior are performed for prediction and optimization.</p></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the separation performance of a three-product hydrocyclone with overflow reseparation","authors":"","doi":"10.1016/j.powtec.2024.120303","DOIUrl":"10.1016/j.powtec.2024.120303","url":null,"abstract":"<div><p>This manuscript proposes a three-product hydrocyclone with overflow reseparation to reduce the particle misplacement in overflow, which achieves secondary separation by utilizing the after-energy of internal swirling flow. Numerical simulations and physical tests were applied to investigate the separation performance. The simulation results revealed that the coarser particles entrapped were effectively recovered by sideflow, the recovery of 20 μm particles in the overflow decreased by 16.71 % ∼ 23.09 % with significant fineness improvement compared with conventional hydrocyclone. The intensity of the internal centrifugal field decreased with the overflow separation chamber expanded, which resulted in an increased probability of particle misplacement during overflow. The test results revealed that the particle content of more than 20 μm in overflow was reduced by 2.44 % compared with conventional hydrocyclone, reducing the overflow separation chamber increased the sideflow ratio and solid phase yield, increased the difference in fineness between sideflow and overflow, and improved the narrow-grain separation performance.</p></div>","PeriodicalId":407,"journal":{"name":"Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}