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Numerical simulation of the drag and heat-transfer characteristics around and through a porous particle based on the lattice Boltzmann method

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Particuology 2021年第5期19卷 99-107页

作者： Mingyue Zhang Qiuyang Zhao Zujie Huang Lei Chen Hui Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

porous particle flow is universal in nature and ***,in previous numerical simulations,porous particles have usually been assumed to be *** is necessary to study the flow and heat-transfer characteristics around porous particles because they are greatly different from those of impermeable *** this study,two-dimensional steady flow and heat transfer around and through a porous particle with a constant temperature placed in a cold fluid were numerically *** effects of the Reynolds number(Re)and Darcy number(Da)on the flow and heat-transfer characteristics were investigated in *** investigated ranges of the parameters were 10≤Re≤40 and 10^(−6)≤Da≤10^(−2).It is sophisticated to simulate porous particles with traditional simulation methods because of their complicated ***,the lattice Boltzmann method was used to solve the generalized macroscopic governing equations because of its *** drag coefficient decreased with increasing Re or Da,but the decrease was not prominent in the range 10^(−6)≤Da≤10^(−4).The heat-transfer efficiency of the front surface was much stronger than that of the rear *** heat-transfer efficiency between the particle and the fluid increased with increasing Re or ***,for 10^(−6)≤Da≤10^(−4),the increase was not prominent and the heat-transfer enhancement ratio was slightly larger than ***,the effect of Da became more prominent at larger *** addition,new correlations for the drag coefficient and surface-averaged Nusselt number were obtained based on the simulated results.

关键词： porous particle Darcy-Brinkman-Forchheimer model Flow and heat-transfer characteristics Lattice Boltzmann method Correlation

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Simulation of solute transportation within porous particles during the bioleaching process

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International Journal of Minerals,Metallurgy and Materials 2010年第4期17卷 389-396页

作者： Sheng-hua Yin Ai-xiang Wu Shao-yong Wang Hong-jiang Wang School of Civil and Environmental Engineering University of Science and Technology Beijing Beijing 100083 China School of Mechanical Engineering University of Western Australia Perth 6009 Australia

A mathematical model, accounting for the sulfuric acid and ferric ions diffusion and the copper sulfide mineral leaching process, was developed for an ore particle by considering its porous structure. It was simulated with the simulation tool COMSOL Multiphysics. The simulation results show that the highest acid and ferric concentrations near the particle surface are apparent, while the concentrations in the central particle increase slightly as the less-porous ore core with low permeability prevents the oxidation from penetrating. The extraction of the mineral near the particle surface is the maximum, mainly because of ample sulfuric acid, ferric ions, bacteria, and oxygen available for the leaching process. Because of low oxidation concentration in the central part of the particle, the reaction rate and copper sulphide conversion are small. The simulation shows good agreement with the experimental results.

关键词： simulation solute transportation bioleaching copper sulphide porous particle

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Reduction and subsequent carburization of pre-oxidation magnetite pellets

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Journal of Central South University 2022年第6期29卷 1856-1868页

作者： CHEN Suo CHEN Dong LYU Ya-nan WU Fei-bao YIN Wei-ang School of Iron and Steel Soochow UniversitySuzhou 215131China Department of Mechanical and Electrical Engineering Suzhou Institute of Industrial TechnologySuzhou 215104China

Magnetite is a kind of iron ore that is difficult to *** order to improve the carburizing performance of magnetite pellet,pre-oxidation treatment was carried out,and the oxidation,reduction and carburization behaviors of magnetite pellet were investigated in this *** magnetite pellet was oxidized in the air and carburized in CO-CO_(2)-H_(2) gas mixtures,the oxidation,reduction and carburization behaviors were demonstrated by detecting phase change,microstructure,carburizing index via thermogravimetry,X-ray diffraction(XRD),infrared carbon-sulfur analyzer,and scanning electron microscope(SEM).The results show that the dense magnetite particles inside pellet are oxidized to porous hematite particles,and the Fe_(3)O_(4) transforms to Fe_(2)O_(3) with high lattice defect concentration during the pre-oxidation *** the porous hematite particles and newly formed Fe_(2)O_(3) significantly promote the reduction *** metallic iron particles are produced in the reduction ***,both high reduction efficiency and the porous structure of metallic iron particles dramatically enhance the carburization efficiency of *** preoxidation temperature favors to the carburization of magnetite ***,the carburized index decreases due to the recrystallization of iron oxide when the temperature extends to 1000℃.The optimum pre-oxidation temperature for magnetite pellet carburization is 900℃.

关键词： magnetite pre-oxidation carburization porous particle recrystallization

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FORMATION OF MICRO-porous SPHERICAL particleS OF CALCIUM SILICATE(XONOTLITE) IN DYNAMIC HYDROTHERMAL PROCESS

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China Particuology 2004年第3期2卷 124-127页

作者： MaoqiangLi HongxunLiang ChinaBuildingMaterialsAcademy.Beijing100024 P.R.China ZhongbeiGlassTechnologyCompany.Beijing100831 P.R.China

Stirring during hydrothermal synthesis plays an important role in the formation of porous spherical xonotlite particles. The size of spherical particles formed during dynamic hydrothermal process is related to the size of minimum vortices in the reaction slurry, which is determined by stirring speed. The kinetics of growth of xonotlite particles is de-termined by measuring the apparent viscosity of the reactant slurry at various reaction time and reaction temperatures. It is found that the growth of particles follows the contracting-volume equation, and the activation energies for nucleation and growth are 104 and 123 ***-1, respectively.

关键词： porous particle xonotlite dynamic hydrothermal synthesis

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