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CFD-DEM simulation of fluorination reaction in fluidized beds with local grid and time refinement method

Particuology 2024年第1期84卷 145-157页

作者： Mofan Qiu Lin Jiang Rongzhen Liu Yaping Tang Malin Liu institute of Nuclear and new energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing100084China

The gas-solid reaction process with wide particle size distribution is extensively used in the chemical engineering field,especially the particle reacts with the gas gradually,such as fluorination reactions in fluidized beds.When the computational fluid dynamics-discrete element method(CFD-DEM)is used for the coupling simulation of multiphase and polydisperse particle reaction system,the grid size directly affects the accuracy of flow field information and simulation of chemical reaction.Furthermore,particle calculation time step will directly affect the efficiency of coupling calculation.In this work,a local grid and time step refinement method is proposed to simulate multiphase and polydisperse particle fluid-ization reaction system.In this method,the refined DEM grids are automatically generated in the computational domain around the fine particles,and the detailed fluid phase information is obtained with the interpolation algorithm.In the two-phase coupling process,particles are divided into different groups based on physical properties,each group has its own independent time step.The multistage conical-cylindrical spouted bed is proposed for the fluorination reaction process;the operating gas ve-locity range of the polydisperse particle system is extended by the new design while the particle size distribution changes with the gas-solid reaction process.It is demonstrated that the local grid and time step refinement method can improve the accuracy and efficiency of the traditional CFD-DEM method in the reaction process simulation,which describes a polydisperse particle system with wide particle size distribution.Aimed at improving the simulation accuracy and efficiency,this paper will be helpful for simulating the particle reaction process in the gas-solid fluidized bed and beneficial for the development of the CFD-DEM method.

关键词： CFD-DEM Polydisperse particle Two-phase flow Fluidized bed

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CFD-DEM simulation of high density particles fluidization behaviors in 3D conical spouted beds

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Particuology 2024年第5期88卷 266-281页

作者： Lin Jiang Mofan Qiu Rongzheng Liu Bing Liu Youlin Shao Malin Liu institute of Nuclear and new energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua UniversityBeijing 100084China

The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated systematically.The cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted bed.It was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional toρp 0.65 and N p 0.78 when the particle density or loading was increased.These results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.

关键词： Spouted bed High-density particle CFD-DEM Fluidization quality index Particle loading

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Numerical simulation of uranium tetrafluoride fluorination in a multistage spouted bed using the improved CFD-DEM chemical reaction model

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Particuology 2023年第4期75卷 119-136页

作者： Mofan Qiu Zhao Chen Lin Jiang Rongzhen Liu Yaping Tang Malin Liu institute of Nuclear and new energy technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyTsinghua University.Beijing.100084China

A CFD-DEM reaction coupling model was established to simulate UF_(4) fluorination process,in which heat and mass transfer,heterogeneous chemical reaction,and particle shrinkage model were considered.The gas behavior was described by the conservation laws of mass,momentum,and energy.The solid phase is modeled with the discrete element method,considering the gas-solid interphase force,contact force,heat transfer,and chemical reaction models based on the discretized surface.Each particle can be individually tracked and associated with specific physical properties.The proposed CFD-DEM reaction coupling model based on particle shrinking reaction model with discretized surface was validated by the experimental and literature results at first.Then a multistage conical spouted bed was proposed and the process of UF_(4) fluoridation reaction in it was investigated.The fluidization characteristics and the con-centration distribution of gaseous products in the spouted bed with an extended gas velocity range were obtained and analyzed.In addition,the effects of different parameters,such as superficial gas velocity,temperature,fluorine concentration,on fluoridation rate and the fluorine conversion rate were inves-tigated based on the proposed CFD-DEM reaction coupling model.The results obtained in this work are beneficial for method development of the chemical reaction simulation research in particle scale using the CFD-DEM model,and useful for operation and equipment parameters design of the uranium tetra-fluoride fluorinate industrial process in the future.

关键词： CFD-DEM Particle shrinkage model Multistage spouted bed Uranium fluorination

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Polyimides as Promising Materials for Lithium-Ion Batteries:A Review

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Nano-Micro Letters 2023年第9期15卷 74-102页

作者： Mengyun Zhang Li Wang Hong Xu Youzhi Song Xiangming He institute of Nuclear and new energy technology Tsinghua UniversityBeijing 100084People’s Republic of China

Lithium-ion batteries(LIBs)have helped revolutionize the modern world and are now advancing the alternative energy field.Several technical challenges are associated with LIBs,such as increasing their energy density,improving their safety,and prolonging their lifespan.Pressed by these issues,researchers are striving to find effective solutions and new materials for next-generation LIBs.Polymers play a more and more important role in satisfying the ever-increasing requirements for LIBs.Polyimides(PIs),a special functional polymer,possess unparalleled advantages,such as excellent mechanical strength,extremely high thermal stability,and excellent chemical inertness;they are a promising material for LIBs.Herein,we discuss the current applications of PIs in LIBs,including coatings,separators,binders,solid-state polymer electrolytes,and active storage materials,to improve high-voltage performance,safety,cyclability,flexibility,and sustainability.Existing technical challenges are described,and strategies for solving current issues are proposed.Finally,potential directions for implementing PIs in LIBs are outlined.

关键词： Polyimides Separators Binders Solid-state electrolytes Lithium-ion

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Tailoring Practically Accessible Polymer/Inorganic Composite Electrolytes for All-Solid-State Lithium Metal Batteries:A Review

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Nano-Micro Letters 2023年第3期15卷 266-297页

作者： Hongmei Liang Li Wang Aiping Wang Youzhi Song Yanzhou Wu Yang Yang Xiangming He institute of Nuclear and new energy technology Tsinghua UniversityBeijing 100084People’s Republic of China

Solid-state electrolytes(SSEs)are widely considered the essential components for upcoming rechargeable lithium-ion batteries owing to the potential for great safety and energy density.Among them,polymer solid-state electrolytes(PSEs)are competitive candidates for replacing commercial liquid electrolytes due to their flexibility,shape versatility and easy machinability.Despite the rapid development of PSEs,their practical application still faces obstacles including poor ionic conductivity,narrow electrochemical stable window and inferior mechanical strength.Polymer/inorganic composite electrolytes(PIEs)formed by adding ceramic fillers in PSEs merge the benefits of PSEs and inorganic solid-state electrolytes(ISEs),exhibiting appreciable comprehensive properties due to the abundant interfaces with unique characteristics.Some PIEs are highly compatible with high-voltage cathode and lithium metal anode,which offer desirable access to obtaining lithium metal batteries with high energy density.This review elucidates the current issues and recent advances in PIEs.The performance of PIEs was remarkably influenced by the characteristics of the fillers including type,content,morphology,arrangement and surface groups.We focus on the molecular interaction between different components in the composite environment for designing high-performance PIEs.Finally,the obstacles and opportunities for creating high-performance PIEs are outlined.This review aims to provide some theoretical guidance and direction for the development of PIEs.

关键词： Polymer Inorganic composite electrolytes All-solid-state lithium metal batteries Fillers Ionic conductivity High voltage

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Revolutionary technology of low-carbon chemical processes

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National Science Review 2023年第9期10卷 15-17页

作者： Suojiang Zhang Xiangping Zhang Chunyan Shi Ke Wang Lei Yuan institute of Process Engineering Chinese Academy of Sciences Longzihu new energy Laboratory Zhengzhou Institute of Emerging Industrial Technology 3. College of Energy Science and Technology Henan University

The chemical industry is one of the key sectors in China.Most chemical processes heavily rely on fossil fuels as energy resources and feedstocks,which inevitably emits a huge amount of CO2.With the global initiative and actions of carbon neutrality,the energy revolution of renewable energy replacing fossil fuels is further promoted towards the ultimate goal that fossil fuels will be fully replaced in the future [1].

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Analysis of the Heat Transfer Efficiency of an Automobile Engine under Different Grille Opening and Closing Conditions

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Fluid Dynamics & Materials Processing 2022年第2期18卷 345-354页

作者： Jian Song College of new energy Vehicles Jingzhou Institute of TechnologyJingzhou434020China

Computational Fluid Dynamics is used to assess the thermal(heat transfer)performances of an automobile engine considering different grille opening and closing degrees.For this purpose the entire vehicle is modelled and three fundamental aspects are examined,namely,the open area of the air intake grille,the position of the upper and lower grilles and their shape.The results show that the opening area and position of the grille have some influence also on the aerodynamic characteristics of the automobile.With an increase in the opening angle of the grille,the CD(Drag Coefficient)value of the whole vehicle becomes higher.When the air intake grille of the car is fully open or closed,the CD value is 0.35434 or 0.31777,respectively,that is,the flow resistance in the engine compartment accounts for 10.32%of the CD value for the whole automobile.

关键词： Air intake grille opening and closing degree automobile engine heat transfer function simulation and optimization

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Optically“silent”neptunium(Ⅴ)-nitrate complex in ionic liquid

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Chinese Chemical Letters 2022年第7期33卷 3531-3533页

作者： Xue Dong Zhipeng Wang Qiang Yan Haiwang Liu Yuxiao Guo Hong Cao Jing Chen Chao Xu institute of Nuclear and new energy technology Tsinghua UniversityBeijing 100084China

The complexation of pentavalent neptunium,Np(Ⅴ),with nitrate ion in an ionic liquid solution has been studied spectroscopically for the first time.The characteristic f-f transition absorption band of Np(Ⅴ)in the NIR region changes significantly upon the titration of nitrate ion into the solution,revealing strong complexation of Np(Ⅴ)with nitrate ion in the ionic liquid.Most notably,the absorption band of Np(Ⅴ)almost disappears when a sufficiently high concentration of nitrate ion is present in the solution.Such a rare optically“silent”species can be assigned to the 1:2 Np(Ⅴ)/nitrate complex with a centrosymmetric coordination environment where Np sits at the inversion center.

关键词： Neptunium Ionic liquid Complexation Absorption f-f transition

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Catholyte engineering to release the capacity of iodide for high-energy-density iodine-based redox flow batteries

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SusMat 2023年第4期3卷 522-532页

作者： Bo Lu Minghui Yang Mei Ding Su Yan Weizhe Xiang Yuanhang Cheng Hu Fu Zhizhao Xu Chuankun Jia institute of energy Storage technology Changsha University of Science&TechnologyChangshaChina School of new energy Nanjing University of Science and TechnologyJiangyinJiangsuChina

Due to the high solubility,high reversibility,and low cost of iodide,iodine-based redox flow batteries(RFBs)are considered to have great potential for upscaling energy storage.However,their further development has been limited by the low capacity of I−as one-third of the I−is used to form I3−(I2I−)during the charging process.Herein,we have demonstrated that the pseudohalide ion,thiocyanate(SCN−),is a promising complexing agent for catholyte of iodinebased RFBs to free up the I−by forming iodine-thiocyanate ions([I2SCN]−)instead of I3−,unlocking the capacity of iodide.Applying this strategy,we have demonstrated iodine-based RFBs with full utilization of iodide to achieve high capacity and high energy density.Both the zinc/iodine RFB and polysulfide/iodine RFB with SCN−complex agent achieve their theoretical capacity of around 160 A h Lposolyte^(−1)(6.0MI−in catholyte).Therefore,the zinc/iodine RFB delivers a high energy density of 221.34Wh Lposolyte^(−1),and the polysulfide/iodine RFB achieves a highenergy density of 165.62Wh Lposolyte^(−1).It is believed that this effective catholyte engineering can be further generalized to other iodine-based RFBs,offering new opportunities to unlock the capacity of iodide and achieve high energy density for energy storage.

关键词： energy storage high energy density iodine-based redox flow batteries unlock iodide capacity

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Multiphysics numerical investigation of photothermal self-driving characteristics of SiO_(2)@Au Janus microparticles for drug delivery

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Particuology 2023年第5期76卷 165-175页

作者： Ying Liu Xinzhi Wang Yurong He School of energy Science and Engineering Harbin Institute of TechnologyHarbin150001China Heilongjiang Key Laboratory of new energy Storage Materials and Processes School of Energy Science and EngineeringHarbin Institute of TechnologyHarbin50001China

The photothermal self-driving process of Janus microparticles has wide application prospects in the fields of biomedicine.Since silica and gold have good biocompatibility and high photothermal conversion efficiency,the SiO_(2)@Au Janus microparticles are widely used as drug carriers.Based on the multiphysics coupling method,the photothermal self-driving process of SiO_(2)@Au Janus microparticles was investi-gated,wherein the substrate was SiO_(2)particles and one side of the particles was coated with gold film.Under a continuous wave laser with irradiation of 20 W/cm^(2),the distance covered by the Janus particles was increased by increasing the thickness of the gold film and reducing the size of the SiO_(2)particles;the self-driving characteristics of the Janus particles were controlled substantially by increasing the intensity of the incident laser.Based on the simulation results,the thermophoretic motion and Brownian motion of particles can be measured by comparing the absolute values of the thermophoretic force impulse,Brownian force impulse,and drag force impulse.The Brownian force acting on Janus microparticles under low laser power cannot be ignored.Furthermore,the minimum laser power required for Janus particles to overcome Brownian motion was calculated.The results can effectively guide the design of Janus particles in biomedicine and systematically analyze the mechanism of particle thermophoretic motion during drug delivery.

关键词： Janus microparticles Photothermal self-driving Multiphysics coupling method Brownian

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