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Discrete particle modeling of granular temperature distribution in a bubbling fluidized bed

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Particuology 2012年第4期10卷 428-437页

作者： Yurong He Tianyu Wang Niels Deen martin van sint annaland Hans Kuipers Dongsheng Wen Department of Power Engineering College of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Chemical Engineering and Chemistry Eindhoven University of TechnologyPO Box 5135600 MB EindhovenThe Netherlands School of Engineering and Materials Science Queen Mary University of LondonMile End RoadLondon El 4NSUK

The discrete hard sphere particle model （DPM） is applied in this work to study numerically the distribu- tions of particle and bubble granular temperatures in a bubbling fluidized bed. The dimensions of the bed and other parameters are set to correspond to those of Miuller et al（2008）. Various drag models and oper- ational parameters are investigated to find their influence on particle and bubble granular temperatures. Various inlet superficial gas velocities are used in this work to obtain their effect on flow characteristics. It is found that the superficial gas velocity has the most important effect on granular temperatures including bubble granular temperature, particle translational granular temperature and particle rotational granular temperature. The drag force model affects more seriously the large scale variables such as the bubble gran- ular temperature. Restitution coefficient influences all granular temperatures to some degree. Simulation results are compared with experimental results by Muller et al. （2008） showing reasonable agreement.

关键词： Bubbling fluidized bedDiscrete hard sphere modelParticle and bubble granular temperature

Velocity equation for grenades while impacting on dry sand media

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Defence Technology（防务技术） 2024年第5期35卷 168-173页

作者： martin Macko Xuan Son Bui Kongsathit Phanthavong Duc Hung Pham van Gion Do van Minh Do Jiri Skala University of Defence BrnoCzech Republic Le Quy Don Technical University Ha NoiViet Nam

This paper deals with the collision of sphere shape grenades with sand *** central issue of the article is the establishing of an empirical velocity equation of the grenade while impacting on sand that is used to solve motion equations of the mechanical mechanism inside the impact grenade *** paper focuses on impact velocities that are lower than 5 m s^(-1).An experiment was conducted to study the velocity of the grenade while impacting on dry sand.A high-speed camera video was used to capture the grenade *** grenade velocity in the impact process was generated from these video *** types of fitting curves are used to regress the velocity equation of the grenade while interacting with the sand media and the best-fitting model is *** result shows the regression curve has a high correlation with the experiment data for grenade velocities below 5 m s^(-1).The received regression equation is useful for analyzing the working ability of the inertial mechanism inside the impact grenade or analyzing and choosing the appropriate parameters of each part in the inertial mechanism to meet the required characteristics of the mechanism.

关键词： Dynamic response Impact velocity Impact grenade Low-velocity impact

Particle mixing rates using the two-fluid model

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Particuology 2018年第1期16卷 13-26页

作者： M. Banaei N.G. Deen M. van sint annaland J.A.M. Kuipers Multiphase Reactors Group Deportment of Chemical Engineering & Chemistry Eindhoven University of Technology 5600 MB Eindhoven The Netherlands Dutch Polymer Institute (DPI) 5600 AX Eindhoven The Netherlands Multiphase and Reactive Flows Group Department of Mechanical Engineering Eindhoven University of Technology 5600 MB Eindhoven The Netherlands

In this work, a new methodology is introduced to calculate the solids mixing rate in dense gas-fluidized beds using the two-fluid model. The implementation of this methodology into an existing two-fluid model code was carefully verified. The solids phase continuity equation was satisfied using our method, and the sensitivity of the computational results to the time step, computational cell size, and discretization scheme was investigated to determine the optimal simulation settings. Using these simulation settings, the degree of solids mixing was observed to rapidly （exponentially） increase with increasing operating pressure and linearly decrease with increasing bed diameter. Our novel methodology can be applied to analyze mixing processes in large lab-scale beds as an alternative to existing time-consuming simulation techniques such as computational fluid dynamics combined with the discrete element model.

关键词： Gas-solid fluidized bed Simulation Two-fluid model Solids mixing Pressure Scale up

Borescopic particle image velocimetry in bubbling gas-solid fluidized beds

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Particuology 2019年第2期17卷 66-75页

作者： M. Banaei R. Dellaert N.G. Deen J.A.M. Kuipers M. van sint annaland Multiphase Reactors Group Department of Chemical Engineering & Chemistry Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands Dutch Polymer Institute (DPI) P.O. Box 902 5600 AX Eindhoven The Netherlands Multiphase and Reactive Flows Group. Department of Mechanical Engineering Eindhoven University of Technology P.O. Box 513 5600 MB Eindhoven The Netherlands

In this work, the borescopic particle image velocimetry (BPIV) technique was applied to a bubbling gas-solid fluidized bed, and the results were compared with published positron emission particle tracking (PEPT) measurement data. Before performing the experiments, the sensitivity of the BPIV results to the illumination power, light reflectivity of the particles, and location of the borescope was also investigated. The BPIV and PEPT results were in fair agreement;however, some discrepancies were *** difference between the two sets of results were mainly caused by the intrusiveness of BPIV, the fact that the local solids volume fraction was not accounted for in the BPIV analysis, and the intrinsic differences of these two methods. Therefore, measurement of the local solids volume fraction with the borescope is highly recommended for further development of the BPIV method, which will also enable measureme nt of the local solids mass fluxes in side dense gas-solid fluidized beds.

关键词： Borescopic particle image velocimetry Gas-solid bubbling fluidized bed Solid velocity profile Experimental investigation Hydrodynamics

Effect of Thermal Cycles on Creep Behavior of Bituminous Binder in Hot Regions

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Journal of Civil Engineering and Architecture 2024年第7期18卷 334-339页

作者： Bachir Glaoui Mahdjoub Bendjima M'hamed Merbouh martin van de Ven Laboratoire de la Fiabilité des Matériaux et Structures en Régions Sahariennes(FIMAS) Université de Béchar B.P.417Béchar08000Algérie Laboratory of Road and Railway Engineering TU DelftP.O.Box 50482600 GA DelftThe Netherlands

This research is devoted to the study of creep behavior of asphalt binder in hot *** binder was subjected to thermal cycles due to the variation of temperature from day to *** cycles produce a heating-cooling *** evaluate the effect of climate change in laboratory,the DSR(dynamic shear rheometer)was used,and the results found with the nine samples were *** thermal cycles led to aging and therefore hardening of the ***,a rheological model was proposed that can represent the curves obtained experimentally,where it is able to describe the creep behavior of binders tested.A new model is proposed that correlates well with the experimental curves,which is called A+2 K.

关键词： Bitumen temperature heating/cooling DSR BBR model

A Comparison of Hydrothermal Aging, SO₂ and Propene Poisoning Effects on NH₃-SCR over Cu-ZSM-5 and Cu-SAPO-34 Catalysts

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Journal of Materials Science and Chemical Engineering 2024年第5期12卷 10-28页

作者： Kouadio Brou Albert Koffi Konan martin Zran van Eric-Simon Horo Kone Unité de Formation et de Recherche des Sciences et de Technologies (UFR ST) Universit&#233 Alassane Ouattara Bouak&#233 C&#244te d&#8217Ivoire Unité de Formation et de Recherche Environnement (UFR E) Universit&#233 Jean Lorougnon Gu&#233d&#233 Daloa C&#244te d&#8217Ivoire Unité de Formation et de Recherche des Sciences des Structures de la Mati&#232re et de Technologie (UFR SSMT) Abidjan C&#244te d&#8217Ivoire

This study was aimed to investigate the effects of hydrothermal aging, propene and SO2 poisoning on the ammonia-selective catalytic reduction (NH3-SCR) performance of both Cu-SAPO-34 and Cu-ZSM-5. The catalytic activities of fresh, aged and poisoned samples were tested in ammonia-selective catalytic reduction (NH3-SCR) of NOx conditions. The XRD, TG and N2-desorption results showed that the structures of the Cu-SAPO-34 and Cu-ZSM-5 remained intact after 750˚C hydrothermally aged, SO2 and propene poisoned. After hydrothermal aging at 750˚C for 12 h, the NO reduction performance of Cu-ZSM-5 was significantly reduced at lower temperatures, while that of Cu-SAPO-34 was less affected. Moreover, Cu-SAPO-34 catalyst showed high NO conversion with SO2 or propene compared to Cu-ZSM-5. However, Cu-ZSM-5 showed a larger drop in catalytic activity with SO2 or propene compared to Cu-SAPO-34 catalyst. The H2-TPR results showed that Cu2 ions could be reduced to Cu and Cu0 for Cu-ZSM-5, while no significant transformation of copper species was observed for Cu-SAPO-34. Meanwhile, the UV-vis DRS results showed that CuO species were formed in Cu-ZSM-5, while little changes were observed for the Cu-SAPO-34. Cu-SAPO-34 showed high sulfur and hydrocarbon poison resistance compared to Cu-ZSM-5. In summary, Cu-SAPO-34 with small-pore zeolite showed higher hydrothermal stability and better hydrocarbon and sulfur poison resistant than Cu-ZSM-5 with medium-pore.

关键词： Hydrothermal Aging Propene and SO2Poisoning Ammonia-Selective Catalytic Reduction(NH3-SCR) Cu-SAPO-34 Cu-ZSM-5

COMPUTATIONAL FLUID DYNAMICS FOR DENSE GAS-SOLID FLUIDIZED BEDS: A MULTI-SCALE MODELING STRATEGY

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China Particuology 2005年第1期3卷 69-77页

作者： M. A. van der Hoef M. van sint annaland J. A. M. Kuipers Department of Science & Technology University of Twente 7500 AE Enschede The Netherlands

Dense gas-particle flows are encountered in a variety of industrially important processes for large scale production of fuels, fertilizers and base chemicals. The scale-up of these processes is often problematic and is related to the intrinsic complexities of these flows which are unfortunately not yet fully understood despite significant efforts made in both academic and industrial research laboratories. In dense gas-particle flows both (effective) fluid-particle and (dissi-pative) particle-particle interactions need to be accounted for because these phenomena to a large extent govern the prevailing flow phenomena, i.e. the formation and evolution of heterogeneous structures. These structures have significant impact on the quality of the gas-solid contact and as a direct consequence thereof strongly affect the performance of the process. Due to the inherent complexity of dense gas-particles flows, we have adopted a multi-scale modeling approach in which both fluid-particle and particle-particle interactions can be properly accounted for. The idea is essentially that fundamental models, taking into account the relevant details of fluid-particle (lattice Boltzmann model) and particle-particle (discrete particle model) interactions, are used to develop closure laws to feed continuum models which can be used to compute the flow structures on a much larger (industrial) scale. Our multi-scale approach (see Fig. 1) involves the lattice Boltzmann model, the discrete particle model, the continuum model based on the kinetic theory of granular flow, and the discrete bubble model. In this paper we give an overview of the multi-scale modeling strategy, accompanied by illustrative computational results for bubble formation. In addition, areas which need substantial further attention will be highlighted.

关键词： dense gas-solid flow gas-fluidized beds multi-scale modelling

Cosmetic or Dietary Vegetable Oils Sampled in the Cameroonian Market May Not Expose Consumers to Lipid Oxidation Products Generating Oxidative Stress and Inflammation

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American Journal of Plant Sciences 2024年第3期15卷 193-202页

作者： Ferdinand Kouoh Elombo Erika van Damme Clara Delepine David Depraetere Ludovic Chaveriat Paul Lunga Keilah Nico Fréderic Njayou Patrick martin Laboratory of Toxicology and Pharmacology Department of Biochemistry Faculty of Sciences University of Yaound&#233 I Yaound&#233 Cameroon Dé partement de Chimie IUT B&#233thune Universit&#233 d&#8217Artois B&#233thune France Unité Transformations & Agroressources (ULR7519) Universit&#232 d&#8217Artois-UniLaSalle Bethune France

Vegetable oils are a source of energy, essential fatty acids, antioxidants and fat-soluble vitamins useful for human health care and development. These oils also contribute to organoleptic quality of their products’ derivatives. However, their chemical and physical properties can be modified by the mode of their extraction, storage and distribution. These modifications might negatively affect the nutritional quality of the oils. The goals of this study were to: sample different vegetable oils for cosmetic or dietary use marketed in Cameroon, and verify purity and oxidation states of each kind of oil through determination of its acidity, iodine, peroxide, saponification, refractive indexes and the conformity of the labeling. The carotene content, the level of polar components and specific absorbance were also determined. As the result, six oils namely palm, palm kernel, coconut, black cumin, peanut and shea butter were collected. Apart from labeling, chemicals and physicals parameters analyzed were generally in accordance with the Cameroonian and Codex Alimentarius standard. This study suggests that vegetable oils sampled in the Cameroonian market may not expose consumers to lipid oxidation products generating pathological oxidative stress and inflammation. However, efforts in application of existing standard need to be done as far as labeling are concerned.

关键词： Vegetable Oils Quality Control Labeling Compliance Lipid Oxidation Oxidative Pathology

Exercise training improves long-term memory in obese mice

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Life Metabolism 2024年第1期3卷 37-50页

作者： Oliver K.Fuller Casey L.Egan Tina L.Robinson Nimna Perera Heidy K.Latchman Lauren V.Terry Emma D.McLennan Carolina Chavez Emma L.Burrows John W.Scott Robyn M.Murphy Henriette van Praag martin Whitham Mark A.Febbraio Monash Institute of Pharmaceutical Sciences Monash UniversityMelbourneVictoria3052Australia La Trobe Institute for Molecular Science La Trobe UniversityMelbourneVictoria3086Australia Florey Institute of Neuroscience and Mental Health University of MelbourneMelbourneVictoria3052Australia Department of Biomedical Sciences Charles E.Schmidt College of Medicineand Stiles-Nicholson Brain InstituteFlorida Atlantic UniversityJupiterFL 33458United States College of Life and Environmental Sciences University of BirminghamEdgbastonBirmingham B152TTUnited Kingdom

Obesity has been linked to a range of pathologies,including *** contrast,regular physical activity is associated with the prevention or reduced progression of ***,physical activity can improve memory and spatial cognition,reduce age-related cognitive decline,and preserve brain volume,but the mechanisms are not fully ***,we investigated whether any detrimental effects of high-fat diet(HFD)-induced obesity on cognition,motor behavior,adult hippocampal neurogenesis,and brain-derived neurotrophic factor(BDNF)could be mitigated by voluntary exercise training in male C57Bl/6 ***-induced impairment of motor function was not reversed by ***,voluntary wheel running improved long-term memory and increased hippocampal neurogenesis,suggesting that regular physical activity may prevent cognitive decline in obesity.

关键词： obesity exercise cognition