Particuology最新文献

{"title":"Critical state uniqueness of dense granular materials using discrete element method in conjunction with flexible membrane boundary","authors":"Chenglong Jiang ,&nbsp;Yajing Liu ,&nbsp;Lingling Zeng ,&nbsp;Chengshun Xu ,&nbsp;Peng Cao","doi":"10.1016/j.partic.2024.09.006","DOIUrl":"10.1016/j.partic.2024.09.006","url":null,"abstract":"<div><div>An explanation of the meso-mechanism of sand granular materials for the uniqueness of critical state is presented by means of the discrete element method (DEM) under flexible boundary loading conditions. A series triaxial drainage shear test (DEM simulations), in conjunction with the flexible boundary technique, of were performed for sand samples subjected to various physical states and with different particle size distributions. After carefully investigating the critical status of the results of the numerical calculation, the macroscopic failure modes and shear band evolution of sand, as well as the velocity vector field due to different initial states, were explored and classified. Furthermore, the evaluation rules and discrepancies between overall void ratios of the specimen and local void ratios within the shear band under the critical state were recorded and analyzed. The results proved that a sample with a small void tends to form a shear band, and the rotation of the particles in the non-shear zone is negligible. Conversely, sandy soil with large initial void ratios exhibited limited development of significant shear bands, and the change in void ratios within the shear region and the non-shear area are not significant. Interestingly, the particle-size distribution exerts minimal influence on the evolution rule which the void ratio converges within the shear band and diverges outside the shear region for both multi-stage and single-stage specimens. The void ratio within the shear band and deviator stress ratio tend to exhibit consistently for the same specimen with different initial physical states, thereby distinguishing the critical state. There is a significantly higher change in void ratio within the shear band compared to outside of it, yet it remains stable within a relatively similar range. Additionally, the invariant of the fabric tensor used to describe the critical state characteristics also demonstrates a high degree of consistency within the shear band. These findings strongly indicate that the critical state exists within the shear failure surface and is highly likely to be unique.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"95 ","pages":"Pages 124-144"},"PeriodicalIF":4.1,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142416651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study on variable load regulation of circulating fluidized bed with high temperature preheated activated fuel","authors":"Weijian Song ,&nbsp;Zihua Tang ,&nbsp;Guoliang Song ,&nbsp;Jianguo Zhu ,&nbsp;Jingzhang Liu ,&nbsp;Haiyang Wang ,&nbsp;Yinjiang Zhang","doi":"10.1016/j.partic.2024.09.007","DOIUrl":"10.1016/j.partic.2024.09.007","url":null,"abstract":"<div><div>The circulating fluidized bed (CFB) boiler is an essential option, serving as a flexible power source. However, it is notable that CFB boilers exhibit noticeable limitations in rapid load changes. This study delved into the impact of fuel characteristics on CFB load change rate, combustion efficiency, and original NO_<em>x</em> emissions using a 2 MW CFB experimental platform. The findings revealed that blending pulverized coal or modified fuel positively influenced the improvement of CFB load change rate, with blending modified fuel showing a more significant effect. Blending the modified fuel and pulverized coal increased the load change rate within the 50%–100% range by 164.4% and 57.3%, respectively. Additionally, blending pulverized coal and modified fuel significantly reduced NO_<em>x</em> emissions, although there remained room for improvement in combustion efficiency. Compared to conventional combustion, blending pulverized coal and blending modified fuel decreased NO_<em>x</em> emissions by 35.9% and 41.4% at 100% load, respectively.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"95 ","pages":"Pages 178-188"},"PeriodicalIF":4.1,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combining Ultra-Turrax and ultrasonic homogenization to achieve higher vitamin E encapsulation efficiency in spray drying","authors":"Letícia Siqueira ,&nbsp;Cristiano Augusto Ballus ,&nbsp;Eduardo Hiromitsu Tanabe ,&nbsp;Daniel Assumpção Bertuol","doi":"10.1016/j.partic.2024.09.005","DOIUrl":"10.1016/j.partic.2024.09.005","url":null,"abstract":"<div><div>Vitamin E, a soluble antioxidant widely used in the food and pharmaceutical industries, is rich in tocopherols and phytosterols. Since vitamin E molecules are highly sensitive to oxidation, encapsulation is a viable and effective technique for preservation of the properties of Vitamin E and improving its stability during storage, maintaining the nutritional value. In this work, the aim was to encapsulate concentrated vitamin E using a combination of Ultra-Turrax and ultrasonication to achieve higher encapsulation efficiency in spray drying. In the first stage, the vitamin E oil was encapsulated employing only Ultra-Turrax homogenization, with subsequent optimization of spray drying. The coating materials used were maltodextrin and whey protein isolate. Optimization of the spray drying step evaluated the effects of the drying air temperature (<em>T</em>) and the feed flow rate (<em>Q</em>), to obtain better yields and a high-quality product. In the second stage, the use of ultrasonication in an additional homogenization step was evaluated, aiming to further improve the encapsulation process. The results showed that the best drying conditions (first stage) were <em>T</em> = 180 °C and <em>Q</em> = 0.6 L/h, which provided the highest yield (67.73%) and high encapsulation efficiency (73.73%). The microspheres produced had similar properties, with mean diameters ranging from 0.64 to 12.99 μm. In the second stage of the investigation, the application of ultrasonication immediately after the Ultra-Turrax homogenization enabled the encapsulation efficiency to be increased to 94.05%, with a yield of 57.54%, using an ultrasonication time of only 7 min. This showed that addition of the ultrasonic homogenization step to the process greatly improved the encapsulation efficiency and could be used to produce vitamin E-enriched powder microcapsules by spray drying, with application in the food industry.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"95 ","pages":"Pages 28-35"},"PeriodicalIF":4.1,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas-rigid-flexible compound blade coupling enhanced experimental study on chaotic mixing of multiphase flow","authors":"Yan Zhang ,&nbsp;Xinyu Li ,&nbsp;Gai Zhang ,&nbsp;Mingyang Fan ,&nbsp;Jianxin Xu ,&nbsp;Hua Wang","doi":"10.1016/j.partic.2024.09.004","DOIUrl":"10.1016/j.partic.2024.09.004","url":null,"abstract":"<div><div>Efficient fluid mixing is essential for process intensification. This study proposes a new method in which gas-rigid-flexible composite blades are coupled to enhance chaotic mixing in multiphase flow systems. The rigidity and flexibility of the blades were adjusted by intermittent gas injection, which increased the effectiveness of mixing of the liquid-liquid two-phase fluid. This study investigates the influence of different process parameters on the mixing efficiency and quantifies the chaotic characteristics of fluid mixing through pressure-time series analysis of multiscale entropy and the 0–1 test. A high-speed camera recorded the bubble movement in the flow field, while particle image velocimetry (PIV) revealed the enhancement of the properties of the flow field in the system due to the suspended motion of the particles. Using suitable process parameters, gas-rigid-flexible composite blade coupling significantly enhanced the mixing effect, where the mixing time of the G-RFCP system was reduced by 1.42 times compared to that of the CP system. Bubble motion, deformation, and rupture enhanced the mechanical agitation, increasing the intensity of the turbulence and chaotic behaviour. Flow-field analysis indicated a three-fold increase in the vorticity and a 1.04-fold increase in the velocity difference for the G-RFCP system compared with those of the CP system. This study provides theoretical and experimental foundations for understanding chaotic mixing in liquid-liquid two-phase fluids.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"94 ","pages":"Pages 356-372"},"PeriodicalIF":4.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of particle Froude number on sub-grid effective drag, filtered and residual stresses in fluidized gas-particle flows","authors":"Christian C. Milioli,&nbsp;Fernando E. Milioli","doi":"10.1016/j.partic.2024.09.002","DOIUrl":"10.1016/j.partic.2024.09.002","url":null,"abstract":"<div><div>Sub-grid effective drag, filtered and residual stresses in the meso-scale of gas-particle fluidized flows are intrinsically affected by underlying micro-scale conditions as well as non-local effects related to macro-scale conditions. In this work we applied microscopic two-fluid modeling to experiment with particle Froude number in order to evaluate the impact of this micro-scale condition over the concerning meso-scale derived sub-grid parameters. We performed highly resolved simulations in periodic domains for particle Froude numbers from 12.21 to 799.22, for a wide range of macro-scale conditions. Results were filtered and classified by ranges of meso-scale markers for the various particle Froude numbers. The particle Froude number was found to considerably affect the structural refinement of the heterogeneous flow fields thereby directly impacting effective drag, filtered and residual stresses. All of those parameters showed systematic behaviors in relation to particle Froude number, thereby providing sound data for new sub-grid modeling propositions.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"95 ","pages":"Pages 36-48"},"PeriodicalIF":4.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Arch formation mechanism and discharge process of cohesive fine powder in a vibrated silo","authors":"Jingzhen Zhu ,&nbsp;Kun Wang ,&nbsp;Yu Ma ,&nbsp;Wentao Xu ,&nbsp;Jiecai Long ,&nbsp;Xiwen Li","doi":"10.1016/j.partic.2024.09.001","DOIUrl":"10.1016/j.partic.2024.09.001","url":null,"abstract":"<div><div>The arch formation mechanism and discharge process of a very cohesive fine powder (calcium carbonate) in a vibrated silo was investigated by experiments and discrete element method (DEM) simulations. An experimental setup is built to study the flow behaviors with the proposed image-based flow rate measurement method. A cohesive DEM model is used to investigate the dynamic behaviors of the powder bed. Results indicate that the arch formation depends on the vibration acceleration amplitude and is slightly affected by the frequency. The powder discharge flow rate increases with vibration acceleration amplitude and decreases with frequency. When the acceleration amplitude exceeds 15 g, the flow rate tends to stabilize. When the acceleration amplitude exceeds 1 g, there is separation and collision between the powder bed and the silo bottom. This collision leads to a significant increase in the contact force.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"94 ","pages":"Pages 373-385"},"PeriodicalIF":4.1,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142315899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improved mesh-free SPH approach for loose top coal caving modeling","authors":"Xiangwei Dong ,&nbsp;Qiang Zhang ,&nbsp;Yang Liu ,&nbsp;Xin Liu","doi":"10.1016/j.partic.2024.08.016","DOIUrl":"10.1016/j.partic.2024.08.016","url":null,"abstract":"<div><div>This study presents an innovative model in computational geotechnical engineering by improving the Smoothed Particle Hydrodynamics (SPH) method for simulating loose particle dynamics in coal caving processes. The improved model integrates an elastic-perfectly plastic constitutive model with the Drucker-Prager yield criterion and includes several improvements aimed at boosting accuracy, stability, and efficiency. These improvements include gravity loading coupled with particle damping, first-order stress field smoothing, and kernel gradient correction. A series of numerical experiments validates the effectiveness of the improved SPH model, demonstrating its capability to predict large deformations and track the evolution of the coal-rock interface in coal caving processes. Furthermore, the study analyzes the model's sensitivity to material parameters such as the angle of friction and material density, which aids in configuring the model for distinct coal mining situations. Results show that the non-cohesive elastic-perfectly plastic constitutive model can effectively simulate the flow behavior of granular particles, and the landslide simulation results are in good agreement with the experiments. The improved SPH algorithm with stress smoothing technique solves the problem of numerical noise, and the “double peak” stress distribution around the coal outlet is identified. The established SPH model offers an effective tool for understanding dynamics behaviors of loose top coal. Significantly, the model requires only five material parameters, which can be identified through standard experiments, avoiding the typically arduous process of parameter selection or calibration commonly existing in Discrete Element Method simulations.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"95 ","pages":"Pages 1-27"},"PeriodicalIF":4.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142323842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of blade geometry on the powder spreading process in additive manufacturing","authors":"Deze Yang ,&nbsp;Xihua Chu ,&nbsp;Qipeng Liu","doi":"10.1016/j.partic.2024.08.018","DOIUrl":"10.1016/j.partic.2024.08.018","url":null,"abstract":"<div><p>In powder-bed-based additive manufacturing, the quality of the powder bed is closely related to the geometry of the blade used during the powder spreading process. In this study, the spreading process with the vertical blade, inclined blade, and round blade with different radii was performed by discrete element method to investigate the effects of blade geometry on powder spreading. The results show that at the same spreading parameters, the round blade caused the highest density than inclined blade and vertical blade. Increasing the round blade radius can improve the packing density of the powder bed, but it has little effect on the uniformity. The increase in packing density is related to the transitional smoothness of the blade surface at the entrance of the powder bed. The smoother the shape transition of the blade surface at the powder bed entrance, the powders enter the powder bed more gently, so more powders enter the powder bed, resulting in higher packing density. The results may provide suggestions for improving the laser melting process.</p></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"94 ","pages":"Pages 345-355"},"PeriodicalIF":4.1,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A numerical investigation on heat transfer characteristics of a particle cluster in fluid with variable properties","authors":"Xiaoyu Li,&nbsp;Huibo Wang,&nbsp;Bowei Zhang,&nbsp;Hui Jin","doi":"10.1016/j.partic.2024.08.019","DOIUrl":"10.1016/j.partic.2024.08.019","url":null,"abstract":"<div><p>This work investigates the heat transfer characteristics of particle clusters under the effects of the complex properties of supercritical water (SCW). It analyzes the heat transfer characteristics of sub-particles and the average heat transfer characteristics of particle clusters. The results reveal a phenomenon of shifting positions of high specific heat regions. It led to variations in the dimensionless heat transfer coefficient distribution. Furthermore, the results indicate that as the heat transfer process strengthens, the effects of variations in property distribution on heat transfer tends to stabilize. Based on this conclusion, the effects of variations in property distribution on heat transfer are categorized into Stable Effects Region and Non-Stable Effects Region. By utilizing the principles of fluid flow-heat transfer coupling and similarity, a heat transfer prediction model for particle clusters in SCW is established.</p></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"94 ","pages":"Pages 327-344"},"PeriodicalIF":4.1,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142243094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the flotation behavior and interaction characteristics of micro-fine quartz and magnesite in a dodecylamine system under ultrasonic treatment","authors":"Xiufeng Gong ,&nbsp;Jin Yao ,&nbsp;Wanzhong Yin ,&nbsp;Jianwei Yu ,&nbsp;Bin Yang ,&nbsp;Yulian Wang","doi":"10.1016/j.partic.2024.08.017","DOIUrl":"10.1016/j.partic.2024.08.017","url":null,"abstract":"<div><div>Ultrasonic treatment, as an important surface modification method, profoundly affects the flotation behavior of minerals. This study examined the impact of ultrasonic treatment on the surface properties and flotation performance of magnesite and quartz in a dodecylamine (DDA) flotation system. Atomic force microscope detection results revealed that the surface roughness and roughness size of both magnesite and quartz increased after ultrasonic treatment. Flotation tests indicated that the recovery rates of magnesite and quartz were lower after ultrasonic treatment. At pH of 10 and DDA of 75 mg/L, ultrasonic treatment led to a 0.66%, 3.46%, and 0.33% decrease in the flotation recovery rates for three different magnesite particle sizes. Following ultrasonic processing, the flotation recovery rates for three different quartz particle sizes decreased by 8.48%, 30.76%, and 43.69%, in that order. X-ray photoelectron spectroscopy detection results showed an increased presence of characteristic Mg and Si sites on the surfaces of magnesite and quartz following ultrasonic treatment. DDA acted on the surfaces of the two minerals through electrostatic adsorption and hydrogen bonding adsorption and repelled the flotation of minerals owing to the same charge as characteristic sites, thereby reducing flotation recovery. Adsorption capacity tests and contact angle measurements demonstrated a decrease in DDA adsorption and contact angle on the surfaces of magnesite and quartz after ultrasonic treatment, explaining the reduced floatability. Extended Derjaguin–Landau–Verwey–Overbeek theoretical calculations indicated that before ultrasonic treatment, there was a repulsive energy between magnesite and fine-grained quartz particles. After ultrasonic treatment, the interaction energy between magnesite and fine quartz particles is mutual attraction.</div></div>","PeriodicalId":401,"journal":{"name":"Particuology","volume":"94 ","pages":"Pages 386-399"},"PeriodicalIF":4.1,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142324186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}