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Equilibrium charge and triboelectric coefficient of spheres in a rotating container

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Particuology 2022年第4期20卷 103-111页

作者： Jiawei Hu Cai Liang Qun Zhou Jiliang Ma Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096China

Contact electrification occurs in many granular material systems due to particle-particle and particle-wall contacts.In this paper,we used a simple device to characterize the electrification of different spheres in a rotating spherical container.The charge of the spheres was quantified by a Faraday cup after rotating for various time and the disperse behaviors of charged spheres were recorded by a camera.The effects of the rotational time,sphere size,rotational speed,sphere material,and relative humidity on the equilibrium charge and triboelectric coefficient were analyzed.The results show that the equilibrium surface charge density is independent of the sphere size and the rotating speed,whereas the larger rotating speed enhances the triboelectric coefficient.It is also shown that charge relaxation constants are two orders of magnitude lower than the charge generation constants for all spheres at a low relative humidity.The increase of water molecules in the air was found to result in the decline of charge generation constant and the rise of charge relaxation constant,which together cause the decrease of the equilibrium surface charge density.

关键词： Particle charging Equilibriurm charge Charge relaxation Charge generation electrostatics

Applications of Potential Theoretic Mother Bodies in electrostatics

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American Journal of Computational Mathematics 2017年第4期7卷 481-494页

作者： Nhan T. Tran Department of Mathematics Kansas State University Manhattan USA

Any polyhedron accommodates a type of potential theoretic skeleton called a mother body. The study of such mother bodies was originally from Mathematical Physics, initiated by Zidarov [1] and developed by Björn Gustafson and Makoto Sakai [2]. In this paper, we attempt to apply the brilliant idea of mother body to electrostatics to compute the potentials of electric fields.

关键词： Newtonian Kernel Potential Mother Body Convex Polyhedron Geometry Geophysics electrostatics

An accurate single descriptor for ion–π interactions

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National Science Review 2020年第6期7卷 1036-1045页

作者： Zhangyun Liu Zheng Chen Jinyang Xi Xin Xu Collaborative Innovation Center of Chemistry for Energy Materials Key Laboratory of Molecular Catalysis and Innovative Materials MOE Key Laboratory of Computational Physical Sciences Department of Chemistry Fudan University

Non-covalent interactions between ions and π systems play an important role in molecular recognition,catalysis and biology. To guide the screen and design for artificial hosts, catalysts and drug delivery,understanding the physical nature of ion–π complexes via descriptors is indispensable. However, even with multiple descriptors that contain the leading term of electrostatic and polarized interactions, the quantitative description for the binding energies(BEs) of ion–π complexes is still lacking because of the intrinsic shortcomings of the commonly used descriptors. Here, we have shown that the impartment of orbital details into the electrostatic energy(coined as OEE) makes an excellent single descriptor for BEs of not only spherical, but also multiply-shaped, ion–π systems, highlighting the importance of an accurate description of the electrostatic interactions. Our results have further demonstrated that OEEs from a low-level method could be calibrated to BEs from a high-level method, offering a powerful practical strategy for an accurate prediction of a set of ion–π interactions.

关键词： ion–π interactions physical nature descriptors electrostatics multiply-shaped ions

Reynolds number dependence of particle transport in a 90°bend with electrostatic effects

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颗粒学报:英文版 2023年第6期77卷 91-104页

作者： Yudong Yan Yanlin Zhao Min Liu Jun Yao International Joint Laboratory on Clean Energy Science and Technology Beijing Key Laboratory of Process Fluid Filtration and SeparationCollege of Mechanical and Transportation EngineeringChina University of Petroleum-BeijingBeijing102249China

In this work,particle transport in a fully developed turbulent 90°bend flow at the"electrostatic equi-librium"state is simulated using large eddy simulation coupled with Lagrangian particle tracking technique.The flow Reynolds numbers(based on bulk velocity)considered is from 34000 to 58000.Three particle size 5,10 and 50μm are considered and their corresponding St number are from 2.2 to 547.Simulation results of the bend flow agree well with experimental data.The electrostatic field formed in the bend is symmetric in the spanwise direction but asymmetric in the vertical direction and radial direction,which is independent of Reynolds number.The minimum electrostatic field strength occurs at r/ra=0.25 near the inner wall of the bend.Particles transported in a bend gradually accumulate near the wall due to turbophoresis,such trend is improved by electrostatics.In addition,under the effect of electrostatics,the plume pattern of particle distribution disappeared.Particle concentration at the inner wall of the bend is higher than that at the outer wall,which depends on the combined effect of elec-trostatics and Dean vortices in the bend.

关键词： electrostatics Bend Turbulent flow Particle transport Largeeddy simulation

Theoretical Study of Light(electrostatics) Driven Molecular Switching Processes

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华南师范大学学报(自然科学版) 2014年第6期 139-139页

作者： Ma Jing Tian Ziqi Wang Xingyong School of Chemistry and Chemical Engineering Nanjing University

Switchable molecular electronic devices,which are triggered by electrostatics interactions or UV light,have potential applications in data storage,drug delivery,cell culture,biosensor and tissue engineering.By using quantum chemical calculations and molecular dynamics(MD)simulations,we investigated the conformational change and switching process for several kinds of electro-controllable surface-supported molecular switches.The polarizable

关键词： Driven Molecular Switching Processes electrostatics Theoretical Study of Light

INTERACTION OF SIMILARLY CHARGED SURFACES MEDIATED BY NANOPARTICLES

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Chinese Journal of Polymer Science 2011年第4期29卷 414-420页

作者： Klemen Bohinc Leo Lue Faculty of Health Sciences University of LjubljanaSI-1000 LjubljanaSlovenia Department of Chemical and Process Engineering University of StrathclydeJames Weir Building75 Montrose StreetGlasgow G1 1XJUK

We study the interaction between two like charged surfaces embedded in a solution of oppositely charged multivalent rod-like counterions. The counterions consist of two rigidly bonded point charges, each of valency Z. The strength of the electrostatic coupling increases with increasing surface charge density or valency of the charges. The system is analyzed by employing a self-consistent field theory, which treats the short and long range interactions of the counterions within different approximations. We find that in the weak coupling limit, the interactions are only repulsive. In the intermediate coupling regime, the multivalent rod-like counterions can mediate attractive interactions between the surfaces. For sufficiently long rods, bridging contributes to the attractive interaction. In the strong coupling limit, the charge correlations can contribute to the attractive interactions at short separations between the charged surfaces. Two minima can then appear in the force curve between surfaces.

关键词： electrostatics Nanoparticle interactions Theory.

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A novel dual-material probe for in situ measurement of particle charge densities in gas-solid fluidized beds

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Particuology 2015年第4期13卷 20-31页

作者： Chuan He Xiaotao T.Bi John R.Grace Fluidization Research Centre Department of Chemical and Biological EngineeringThe University of British Columbia

Particle charge density is vitally important for monitoring electrostatic charges and understanding particle charging behavior in fluidized beds. In this paper, a dual-material probe was tested in a gas-solid fluidized bed for measuring the charge density of fluidized particles. The experiments were conducted in a two-dimensional fluidized bed with both single bubble injection and freely bubbling, at various particle charge densities and superficial gas velocities. Uniformly sized glass beads were used to eliminate complicating factors at this early stage of probe development. Peak currents, extracted from dynamic signals, were decoupled to determine charge densities of bed particles, which were found to be qualitatively and quantitatively consistent with charge densities directly measured by Faraday cup from the freely bubbling fluidized bed. The current signals were also decoupled to estimate bubble rise velocities, which were found to be in reasonable agreement with those obtained directly by analyzing video images.

关键词： electrostatics Particle charge density Dual-material collision probe Signal decoupling Fluidized bed Bubble rise velocity

维普期刊数据库

Tribo-charging of binary mixtures composed of coarse and fine particles in gas-solid pipe flow

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Particuology 2019年第2期17卷 101-109页

作者： Haifeng Wang Farzam Fotovat Xiaotao T. Bi John R. Grace Department of Chemical Engineering China University of Mining and Technology. Xuzliou 221166 China Department of Chemical and Petroleum Engineering Sharif University of Technology Azadi Avenue P.O. Box 11365-9465 Tehran Iran Fluidization Research Centre Department of Chemical and Biological Engineering University of British Columbia. Vancouver V6T 1Z3 Canada

Experiments were conducted to investigate the effect of adding fines on the tribo-charging of coarse glass beads. Four types of fines, i.e., copper, stainless steel, uncoated and silver-coated fine glass beads, mixed w让h 240-830 μm glass beads were conveyed by air through a stainless-steel spiral pipe acting as a tribo-charger. Regardless of the type or electrical conductivity of the fine particles tested, adding small amounts of fines (up to 10wt%) to coarse glass beads resulted in a sharp increase in the mass and surface charge densities of the particles. In gen eral, the profiles of the mass and surface charge den sides of the fine-coarse particle mixtures as a function of the mixture composition were determined by the relative magnitude of contact potential differences and the total surface areas of all the comp on ents. The domi nant particle tri bo-electrification mecha nism switched from coarse particle-wall con tacts to fine particle-wall contacts when the fines weight percentage in the mixture exceeded 10%. A model was developed to predict the mass charge density of bi nary mixtures as a function of the mixture composition.

关键词： Tribo-charging electrostatics Fine particles Binary mixture Gas-solid flow

Higher-Order Line Element Analysis of Potential Field with Slender Heterogeneities

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Computers, Materials & Continua 2016年第3期51卷 145-161页

作者： H.-S.Wang H.Jiang B.Yang School of Optoelectronics Beijing Institute of Technology Beijing 100081China Department of Mechanical and Aerospace Engineering University of Texas at Arlington ArlingtonTX 76019USA State Key Laboratory of Digital Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhanHuBei 430074China

Potential field due to line sources residing on slender heterogeneities is involved in various areas,such as heat conduction,potential flow,and electrostatics.Often dipolar line sources are either prescribed or induced due to close interaction with other objects.Its calculation requires a higher-order scheme to take into account the dipolar effect as well as net source effect.In the present work,we apply such a higher-order line element method to analyze the potential field with cylindrical slender heterogeneities.In a benchmark example of two parallel rods,we compare the line element solution with the boundary element solution to show the accuracy as a function in terms of rods distance.Furthermore,we use more complicated examples to demonstrate the capability of the line element technique.

关键词： electrostatics Heat conduction Integral equation technique Line element method Mesh reduction method,Potential field problems