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Effects of calculation approaches for thermal conductivity on the simulation accuracy of billet continuous casting

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International Journal of Minerals,Metallurgy and Materials 2014年第1期21卷 18-25页

作者： Zun Peng Yan-ping Bao Ya-nan Chen Li-kang Yang Cao Xie Feng Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Hangzhou Iron and Steel Group Co.

An unsteady, two-dimensional, explicitly solved fmite difference heat transfer model of a billet caster was presented to clarify the influence of the thermal conductivity of steel on model accuracy. Different approaches were utilized for calculating the thermal conductivity of solid, mushy and liquid steels. Model results predicted by these approaches were compared, and the advantages of advocated approaches were discussed. It is found that the approach for calculating the thermal conductivity of solid steel notably influences model predictions. Convection effects of liquid steel should be considered properly while calculating the thermal conductivity of mushy steel. Different values of the effective thermal conductivity of liquid steel adopted could partly be explained by the fact that different models adopted dissimilar ap- proaches for calculating the thermal conductivity of solid and mushy steels.

关键词： continuous casting solidification heat transfer thermal conductivity mathematical models

The main strategies for soil pollution apportionment:A review of the numerical methods

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Journal of Environmental Sciences 2024年第2期136卷 95-109页

作者： Bin Shi Jing Meng TieyuWang Qianqian Li Qifan Zhang Guijin Su Research Center for Eco-Environmental Sciences Chinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention Shantou UniversityShantou 515063China

Nowadays,a large number of compounds with different physical and chemical properties have been determined in *** behaviors and source identification of pollutants in soil are the foundation of soil pollution *** and quantitative analysis of potential pollution sources are the prerequisites for its prevention and *** efforts have made to develop methods for identifying the sources of soil *** efforts have involved the measurement of source and receptor parameters and the analysis of their relationships via numerical statistics *** have comprehensively reviewed the progress made in the development of source apportionment methodologies to date and present our *** numerical methods,such as spatial geostatistics analysis,receptor models,and machine learning methods are addressed in *** most cases,however,the effectiveness of any single approach for source apportionment remains *** multiple methods to address soil quality problems can reduce uncertainty about the sources of soil *** review also constructively highlights the key strategies of combining mathematical models with the assessment of chemical profiles to provide more accurate source *** review intends to provide a comprehensive summary of source apportionment methodologies to help promote further development.

关键词： Soil pollutants Source attribution Methodologies Chemical profiles mathematical models

Thermal conductivity model of filled polymer composites

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International Journal of Minerals,Metallurgy and Materials 2011年第5期18卷 623-631页

作者： Ming-xia Shen Yin-xin Cui Jing He Yao-ming Zhang College of Mechanics and Materials Hohai University Nanjing 210098 China

Theoretical and empirical models for predicting the thermal conductivity of polymer composites were summarized since the *** effects of particle shape,filler amount,dispersion state of fillers,and interfacial thermal barrier on the thermal conductivity of filled polymer composites were investigated,and the agreement of experimental data with theoretical models in literatures was *** with high thermal conductivity was chosen to mix with polyvinyl-acetate （EVA） copolymer to prepare SiO2/EVA *** data of the co-films＇ thermal conductivity were compared with some classical theoretical and empirical *** results show that Agari＇s model,the mixed model,and the percolation model can predict well the thermal conductivity of SiO2/EVA co-films.

关键词： polymer matrix composites thermal conductivity mathematical models polyvinyl acetates silica filled polymers.

Optimization of flotation variables for the recovery of hematite particles from BHQ ore

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 605-611页

作者： Swagat S. Rath Hrushikesh Sahoo B. Das CSIR-Institute of Minerals and Materials Technology Bhubaneswar 751 013 India

The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite （BHQ） containing 41.8wt% Fe and 41.5wt% SiO2,by using oleic acid, methyl isobutyl carbinol （MIBC）, and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows： collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.

关键词： hematite iron ore treatment flotation metal recovery design of experiments mathematical models opti-mization

mathematical model of burden distribution for the bell-less top of a blast furnace

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 620-626页

作者： Zhao-jie Teng Shu-sen Cheng Peng-yu Du Xi-bin Guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing MCC Capital Engineering and Research Incorporation Limited Xuanhua Iron and Steel Company

Due to the difficulty in measuring the burden trajectory directly in an actual blast furnace （BF）, a mathematical model with Coriolis force and gas drag force considered was developed to predict it. The falling point and width of the burden flow were obtained and analyzed by the model, the velocities of particles at the chute end were compared with and without the existence of Coriolis force, and the effects of chute length and chute torque on the falling point were also discussed. The simulation results are in good agreement with practical measurements with laser beams in a 2500 m3 BF.

关键词： blast furnaces burden trajectories mathematical models Coriolis force

mathematical model of the direct reduction of dust composite pellets containing zinc and iron

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International Journal of Minerals,Metallurgy and Materials 2013年第7期20卷 627-635页

作者： Xiu-wei An Jing-song Wang Xue-feng She Qing-guo Xue State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing School of Mechanical Engineering University of Science and Technology Beijing

Direct reduction of dust composite pellets containing zinc and iron was examined by simulating the conditions of actual production process of a rotary hearth furnace （RHF） in laboratory. A mathematical model was constructed to study the reduction kinetics of iron oxides and ZnO in the dust composite pellets. It was validated by comparing the calculated values with experimental results. The effects of furnace temperature, pellet radius, and pellet porosity on the reduction were investigated by the model. It is shown that furnace temperature has obvious influence on both of the reduction of iron oxides and ZnO, but the influence of pellet radius and porosity is much smaller. Model calculations suggest that both of the reduction of iron oxides and ZnO are under mixed control with interface reactions and Boudouard reaction in the early stage, but only with interface reactions in the later stage.

关键词： rotary hearth furnaces dust zinc ore pellets direct reduction process mathematical models kinetics

Analysis of three-dimensional vortexes below the free surface in a continuous casting mold

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International Journal of Minerals,Metallurgy and Materials 2011年第4期18卷 397-406页

作者： Cesar A.Real-Ramirez Jesus I.Gonzalez-Trejo Universidad Autonoma Metropolitana-Azcapotzalco.San Pablo 180 02200Mexico CityMexico

To study fluctuations of the free surface of liquid steel in the mold,two different models with the same casting conditions but different thicknesses were employed to analyze the hydrodynamic behavior at the top of the *** first model was a standard thickness slab,and the second had a thickness three times *** is found with the second model that above the plane formed by the steel jets,it is possible to observe four three-dimensional vortexes that interact with the submerged entry nozzle（SEN）and mold *** using a biphasic model to simulate the interface between the liquid and air inside the mold,the flow asymmetry and the fluctuations of the free surface can be clearly observed.

关键词： continuous casting molds flow patterns three dimensional vortes mathematical models computer simulation

Unsaturated flow and solute transport in a porous column using spherical ore particles

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 113-121页

作者： Xiu-xiu Miao Ai-xiang Wu Bao-hua Yang Jin-zhi Liu Sheng-hua Yin Hong-jiang Wang Key Laboratory of High-Efficient Mining and Safety of Metal Mines (Ministry of Education) University of Science and Technology Beijing School of Information Science and Engineering Hunan International Economics University College of Information Technology Shanghai Ocean University

This paper dealt with the development of a two-dimensional （2D） mathematical model for column leaching and confirmed the important simulation parameters through experiment. The unsaturated state of the variably saturated flow column and the solute transport of copper ions were studied during leaching. The fluid flow problem was handled using the Richards equation on the premise of an ambient pressure column air, where the van Genuchten formulas were applied to define the nonlinear relationships of pressure head with the retention and permeability properties. The ore column permeability test gave a varied hydraulic conductivity, which was analyzed in the model. In the solute transport problem, the copper ion concentration was solved using the advection-diffusion-reaction equation whose reaction term was determined by the joint analysis of experimental copper leaching rate and the shrinking core model. Particle-and column-scale leaching tests were carried out to illustrate the difference and connection of copper extraction in both processes. This fluid flow and solute transport cou-pled model was determined through the finite element method using the numerical simulation software, COMSOL Multiphysics.

关键词： mathematical models leaching unsaturated flow solute transport

Design and optimization of a novel electrically controlled high pressure fuel injection system for heavy fuel aircraft piston engine

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Chinese Journal of Aeronautics 2018年第9期31卷 1920-1928页

作者： Ke ZHANG Xudong HUANG Zhifeng XIE Ming ZHOU School of Aerospace Engineering Tsinghua University

The heavy fuel compression ignition engines are widely equipped as aircraft piston engines. The fuel injection system is one of the key technologies that determines the performance of engine. One of the main challenges is to precisely control the injected fuel quantity and flow rate in the presence of pressure fluctuation. This challenge is even more serious for heavy fuel. An original design for electrically controlled high pressure fuel injection system called Multi-Pumppressure-reservoirs fuel injection System(MPS) was demonstrated to reduce the pressure fluctuation and help keep injection stable. MPS was compared with an ordinary high pressure Common Rail fuel injection System(CRS). This work established one-dimensional AMESim and mathematical models for both CRS and MPS to study the effect of different structures and geometric parameters on the pressure fluctuations. The calculations show that the average fuel pressure fluctuation of MPS can be reduced by 57% for the crankshaft speed of 1900 r/min, and the pressure fluctuation before injection reduced by 100%. It is concluded that the pressure performance of MPS is less sensitive to pressure reservoir volume than that of CRS, and there is an opportunity for further volume reduction.

关键词： Aircraft engines AMESim Common rail Fuel injection mathematical models Pressure effects Structural design