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Experimental investigation of radiative heat propagation in a simplified generic packed bed

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Particuology 2024年第5期88卷 149-160页

作者： Matthias Tyslik Lukas Pörtner Siegmar Wirtz Martin Schiemann institute of energy plant technology Ruhr-University Bochum44780 BochumGermany

A novel test rig for the investigation of radiative heat transfer in packed beds has been developed and is introduced with representative experimental *** individual components and the calibration are *** generic packed bed is realized in a simplified way by an arrangement of parallel rods,which represent particles in *** this arrangement,electrically heated rods provide the radiation propagating through the rod array to heat the passive counterparts.A sophisticated temperature-control scheme with a large number of thermocouples and infrared-imaging provides in-depth information about heat transfer in the *** radiation intensities are determined with a Fourier-transform infrared spectroscopy,which has been modified and validated for this specific *** order to compare the influence of different surface properties of particles on the heat propagation and surface reflections,rod samples made of stainless steel and magnesium oxide are *** influence of material properties becomes clearly visible by comparing the high radiation intensities resulting from a stainless steel rod array to the same geometry built from magnesium oxide *** addition,the influence of the surface properties is particularly evident in the infrared images since the reflections are significantly higher for the stainless steel samples than for the magnesium oxide *** experimental results in the current work demonstrate the ability of the test rig to provide data with a well-defined accuracy as a validation base for numerical radiation simulations in packed beds.

关键词： Thermal radiation Spectral reflections Fourier-transform infrared spectroscopy

Investigating the inflow into a granular bed using a locally resolved method

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Particuology 2024年第2期85卷 89-101页

作者： Maximilian Brommer Maik Scharnowski Enric Illana Mahiques Siegmar Wirtz Viktor Scherer Ruhr University Bochum Institute of Energy Plant TechnologyUniversitätsstraβe 15044780BochumGermany

Discrete Element Method-Computational Fluid Dynamics(DEM/CFD)simulations of industrial-scale granular systems employ spatial averaging(porous media approach)for the fluid-particle interaction in the whole domain,which can lead to poor accuracy,for instance at flow inlets,as local particle bulk morphology is not *** paper presents an approach where the interstitial flow in crucial areas with large gradients can be resolved locally in an otherwise unresolved domain,so that a mixed resolved-unresolved method is *** a generic example to show the feasibility and performance of the new approach,the inflow of ambient air into a flat-bottom hopper through a narrow orifice is *** an experimental setup,the vertical profile of the pressure decay through the inlet and across the packing is chosen for com-parison with respective *** obtained with the conventional porous media method and the locally resolved approach are compared to these experiments for varying volume flow rates and for two different particle *** of different size as well as dodecahedrons are *** is found that although averaging methods already provide good approximations,the locally resolved method can improve the result especially when conventional drag laws are not applicable due to wall effects or if large velocity gradients exist.

关键词： DEM/CFD Packed bed Pressure drop

Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace

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Particuology 2024年第2期85卷 224-240页

作者： Max Kriegeskorte Nikoline Hilse Phil Spatz Viktor Scherer institute for energy plant technology(LEAT) Ruhr University BochumUniversitätsstraβe 15044780 BochumGermany

In industry,multiple hearth furnaces are used for the thermal treatment of particulate *** current contribution concentrates on the experimental analysis of particle mechanics for a batch-operated single floor of a multiple hearth *** particles are agitated on the circular floor by a single,rotating rabble arm equipped with three flat rabble blades of 10 mm *** blade angle,defined as the angle,which the blade is inclined against the tangential direction,is varied from 0°to 90°.A single layer of spherical polyoxymethylene(POM)particles with three different diameters(5,10 and 20 mm)is placed on the *** analyze the results,two parameters have been extracted from image analysis when the bed of particles is agitated,first,the area not covered by particles and second,the frequency distribution of the mean distance among the *** particle free surface area increases with the inclination of the *** evolution of the particle free surface area differs for the different particle *** general,the maximum particle free area for all blade angles is the largest for the 5 mm particles followed by the 20 mm *** the 10 mm particles,the particle free surface area starts for a blade angle of 0°at larger values than for the 20 mm particles but the values fall below the values for the 20 mm particles for larger blade *** reason for this behavior is discussed in *** mean distance among the particles is a parameter characterizing the length scales dominating the effects on the *** frequency distribution of the mean distance among particles provides infor-mation about the morphology of the particle bulk,for example,whether the free surface area is inter-spersed with particles.

关键词： Hearth furnace floor Particle movement Spherical particles Particle free surface area Mean distance among particles

A numerical and experimental comparison of heat transfer in a quasi two-dimensional packed bed

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Particuology 2024年第1期84卷 136-144页

作者： Matthias Tyslik Mirko Ebert Martin Schiemann Siegmar Wirtz Christian Lessig Department of energy plant technology Ruhr-University BochumGermany institute for Simulation and Graphics Otto-von-Guericke-Universität MagdeburgGermany

Heat transfer plays a major role in many industrial processes taking place in packed *** accurate and reliable simulation of the heat exchange between particles is therefore crucial for a reliable operation and to optimize the processes in the *** discrete ordinates method(DOM)provides an established numerical technique to model radiative heat transfer in granular media that offers the possibility to consider the directional dependence of the radiation *** this work,DOM is compared with Monte Carlo ray tracing,which provides an alternative method for heat transfer ***-rically simple configurations are used to investigate the influence of the angular discretization on the accuracy of the results and the computation time in both *** obtained insights are then transferred to a more complex configuration of a quasi two-dimensional test rig consisting of metal rods for which also experimental results are *** results show that both DOM and Monte Carlo ray tracing allow for an accurate simulation of heat transfer in packed *** Carlo ray tracing requires thereby computation times that are surprisingly competitive(although still somewhat slower)compared to DOM and allows for an easier computation of highly accurate reference *** our preliminary comparison to the experimental test rig,Monte Carlo ray tracing also provides the advantage that it can more easily model highly specular materials such as stainless *** methods are comparable for diffuse materials such as magnesium oxide.

关键词： Heat transfer Discrete ordinates method Monte Carlo ray tracing

Halogen-bond induced unusual polyhalogen anions formation in hydrogen-bonded frameworks to secure iodine sequestration

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Nano Research 2024年第7期17卷 6766-6772页

作者： Yi Xie Pengling Huang Qiang Gao Shiyu Wang Jianchen Wang Gang Ye Collaborative Innovation Center of Advanced Nuclear energy technology Institute of Nuclear and New Energy TechnologyTsinghua UniversityBeijing 100084China

Safe confinement of fission iodine isotopes for long-term radioactive waste disposal remains a formidable challenge,as conventional sorbents provide inherently weak iodine-host *** report here a novel halogen bond(X-bond)directed strategy to sequester volatile iodine in hydrogen-bonded(H-bonded)frameworks with unprecedented ***-assisted Hbonded frameworks bearing open halide sites are developed,showing distinctive iodine encapsulation behaviors without compromising the *** crystallographic evidence indicates the formation of X-bonds,i.e.,I–I···Cl−and I–I···Br^(−),within the confined pore *** polyhalogen anions,i.e.,[I_(2)Cl_(2)]^(2−)and[I_(2)Br_(2)]^(2−),sustained in H-bonded frameworks are identified for the first *** X-bond reinforced host-guest interaction affords robust iodine trapping without leaking out even at elevated temperatures up to 180°*** integrating the halogen-bond chemistry with H-bonded frameworks,this study offers fresh concepts for developing effective host reservoirs to secure fission iodine isotopes from spent fuel reprocessing off-gases.

关键词： halogen-bond chemistry anion coordination chemistry hydrogen-bonded organic frameworks polyhalogen anions iodine confinement

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 fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and *** 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 *** 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 *** was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional to ρ_(p)^(0.65) and N_(p)^(0.78) when the particle density or loading was *** 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

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

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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 *** 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 ***,particle calculation time step will directly affect the efficiency of coupling *** this work,a local grid and time step refinement method is proposed to simulate multiphase and polydisperse particle fluid-ization reaction *** 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 *** the two-phase coupling process,particles are divided into different groups based on physical properties,each group has its own independent time *** 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 *** 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 *** 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

Corrosion evaluation and resistance study of alloys in chloride salts for concentrating solar power plants

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Rare Metals 2024年第3期43卷 1222-1233页

作者： Dong-Mei Han Yong Shuai Bachirou Guene Lougou Bo-Xi Geng Xi-Bo He Tian-Tian Yan Jia-Meng Song School of energy Science and Engineering Harbin Institute of TechnologyHarbin150001China

Thermal energy storage(TES)systems based on molten salt are widely used in concentrating solar power(CSP)*** investigation of the corrosion behavior of alloy materials in molten salt is crucial for the correct selection of alloy materials and the design of TES *** this study,the corrosion behavior of 304,310S,316,and In625 alloys in molten chloride salts(27 mol%NaCl-22 mol%KCl-51 mol%MgCl,)was *** evolution of mass loss of the alloy samples with corrosion time and temperature and the analysis of the experimental results by scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)revealed the corrosion mechanism of the alloy samples in molten chloride *** main factors affecting the corrosion of the alloy samples were further *** was found that the loose multi-layer corrosion was formed on the surface of the corroded alloy samples with the increase in corrosion ***,the experimental *** that Mo played a positive role in improving the corrosion resistance of the alloy samples because the presence of Mo could inhibit the outward diffusion of alloying element *** work enriches the molten salt corrosion database and provides a reference for the selection of alloy materials for TES systems with potential application in CSP plants.

关键词： Thermal energy storage Molten chloride salt Alloy materials Corrosion mechanism Corrosion resistance

Effects of Number of Bleed Holes on Shock-Wave/Boundary-Layer Interactions in a Transonic Compressor Stator

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Journal of Thermal Science 2024年第2期33卷 611-624页

作者： LI Bai ZHOU Xun LUO Lei DU Wei School of energy Science and Engineering Harbin Institute of TechnologyHarbin150001China

An extensive numerical investigation is conducted to characterize the flow separation control in a transonic compressor cascade with a porous *** bleed holes are arranged on the suction surface in a single row,two staggered rows and three staggered *** each bleed scheme,five bleed pressure ratios are examined at an inlet Mach number of *** results indicate that the aerodynamic performance of the cascade is significantly improved by the porous *** the single-row scheme,the maximum reduction in total pressure losses is 57%.For the two-staggered-row and three-staggered-row schemes,there is an optimal bleed pressure ratio of 1.0,and the maximum reductions in total pressure loss are 68% and 75%,*** low loss in the cascade is due to the well-controlled boundary *** new local supersonic region created by the bleed hole is the key reason for the improved boundary *** vortex induced by side bleeding provides another mechanism for delaying flow *** the bleed holes could create multiple local supersonic regions,which reduce the range of the adverse pressure gradient that the boundary layer needs to *** is the reason why cascades with more bleed holes perform better.

关键词： transonic compressor stator shock wave/boundary layer interaction porous bleed number of bleed holes