An optimization method for the nozzle arrangement in secondary cooling zone of continuous casting

Based on the existing research on nozzle arrangement method in secondary cooling zone of continuous casting, the method of superposed water flow density is put forward to optimize the nozzle arrangement at casting direction and transverse section of slab according to the optimization principle. The two-dimension heat transfer model is established. The solidification morphology of cross-section at casting direction is simulated with consideration of the influence of water flow density inhomogeneity on solidification process at transversal section, and the temperature distribution of slab, solidification process, and quality of slab are compared between before and after optimization. The results indicate that the surface temperature of slab is dropped equably after optimization, and the casting blank is cooling uniformly in the water springing zone so as to ensure better quality of the casting blank.     

The Numerical Simulations of the Casting Process for Making Fiber-reinforced Metal Matrix Composite

The numerical simulations of the casting process for making metal matrix composite by infiltrating melting alloys into a fiber preform arestudied. The evaluation of the infiltration flow, the thermal conduction, the stress and strains of the matrix are studied with finite element method, and the corresponding finite element program for axi-symmetry condition is programmed. The influences of the controllable initial and boundary conditions on the casting process, residual stress and residual plastic strains, and selection of optimal technological parameters are researched. The reliability of the numerical simulation is analyzed by comparison between the calculated results andsimilar experimental data.[WT5HZ]     

STUDY ON HEAT TRANSFER MATHEMATICAL MODEL BETWEEN BILLETS AND ROLLERS FOR THE SECONDARY COOLING ZONE IN BILLET CONTINUOUS CASTING

A mathematcal model of heat transfer between the billet and the roller for the seeondary cooling zone in billet continuous casting is established. By means of the simulated test,a regres sion relation between the heat flow from the billet into the roller and the surface temperature and cast ing speed and spray water density obtained. The calculated theoretical values for change of surface temperature are in agreement with the measured data, these studies may contribut to the quantitative analysis and the calculation of the heat transfer of the secondary cooling zone.     

Investigation on flow and heat transfer characteristics in capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC)

An axial symmetric invariable temperature phase change interface model of capillary porous wick based on alkali metal thermal-to-electric converter (AMTEC) is established to simulate flow and heat transfer characteristics in capillary porous wick and liquid channel by solving the mass and heat transport controlling equations. The effects of the working fluid flow rate, inlet temperature, porous wick thickness, porosity and effective pore diameter on the distributions of pressure, velocity and temperature are analyzed. In addition, the available effective pore size of the porous wick and the measures to improve the performance of the porous wick are given by analyzing the relationship between the maximum available capillary pressure and the loop pressure drop. The results show that the model presented in gives a good agreement with the three dimensional two-phase evaporation model. The flow and heat transfer characteristics of the capillary porous wick with the alkali metal liquid as working fluid are different from that with the traditional working fluid in some ways.     

The Mathematical Model of Cooling and Heat Transfer for the Solidification of Thin Slab during Continuous Casting Process

In the established model, the cooling differences are considered between the surface of inner radius and that of outer radius, and in the transverse direction of thin slab. And the conception for the effective coefficient of spraying water in continuous casting is firstly put forward. According to different casting speeds and different cooling zones, different time step lengths are adopted. In this model the heat transfer differences are thought over among vertical and curved zones, wide and narrow surfaces an well as angular zone of mould. The method of the corrected equivalent specific heat is used to deal with latent heat. The influence of forced convection is considered on heat transfer. Therefore, the model has higher accuracy and is consistent with the practice.     

Advance in Mathematic Model of Solidification Heat Transfer Process in Continuous Casting

The mathematic model of solidification heat transfer process in continuous casting strand is useful for quantitatively analyzing heat transfer in continuous casting process, quality control and process control. The heat transfer in continuous cast strand in crystallizer and secondary cooling zone have been analyzed. The attention has been paid to basic logic and methodology in model building up. Typical methods determing solution condition and parameters for the model have been discussed. Some numerical methods at the present time for solving solidification heat transfer model, such as finite difference method, finite-element method and boundary element, have been investigated comparatively. In the future, working on solidification heat transfer model, which is more practical, and the integration of the control model will play an important role in the development of high efficiency continuous casting technology.     

Micromodel of Computer Emulational Simulation on Twin-roll Casting Strip Solidification Structure

Based on the research on the solidifiation of twin-roll casting strip,the analytical model and emulational model of nucleation,the growth of dendrity tip and colunar dendrity transformation to equiaxis dendrity (CET)of twin-roll casting strip solidification are established by means of the principle of metal solidification and modern computer emulational technology.The foundation for the emulational simulation of twin-roll casting strip solidification structure is laid.     

Finite Element Method of 3D Stable Heat Conduction of Steel Fluid in Continuous Casting Moulds

The heat transfer of steel fluid in continuous casting mould is a stable process and can be depicted with three-dimensional stable heat conduction equation depending on tension speed. The corresponding finite element equation, including the first, second and third boundary conditions, is deduced out with Galerkin residual method. The coded FEM program is used to analyze the temperature distribution of Q235 steel in continuous billet casting mould. The method proposed is a foundation of thermo-mechanical coupled analysis for the formation of solidified shells and stress in the shells in continuous casting.     

不同熔化速率下的电渣重熔过程数值模拟分析

电渣重熔能提高钢锭的质量,从而满足特种行业的需要,其过程伴随着复杂的物理现象,存在着磁流体流动、传热和传质以及电化学等多方面的影响。通过耦合电磁以及流动和温度方程对电渣重熔过程的三维瞬态进行了数学模拟,研究了熔化速率对重熔过程的影响。结果表明：电流密度、焦耳热和电磁力都随着熔化速率的增大而增大,当熔化速率由14.4 kg/h增加到27.0kg/h,电流密度、焦耳热和电磁力最大值的增大比例超过100%。随着熔化速率的增大,温度最大值有小幅的增加,而且速度最大值的增大幅度接近50%;金属熔池深度则由27 mm增大到38 mm,不利于保证铸坯的质量。     

Computational Simulation on Temperature Field of Slab Continuous Casting Mold

On the core concepts that the distributing of temperature and solidified slab shell in mold are a stable process, a new method to calculate the temperature field in mold has been promoted. Consequently, a coupling model on fluid filed and temperature field in stable state has also been established. The concept of effective heat capacity is introduced to deal with the latent heat source term from phase transformation. During the programming for computation, the dynamic updating method is also applied to simulate the influence of solidification on physical properties. The resolution results of this model are analyzed and compared with the tested thickness of solidified shell from casting broke out slab, which demonstrates the correctness and applicability of this model to the practical continuous casting process. Additionally, the thickness distribution of solidified shell in slab mold are also studied in detail.     

Simulation for Logistics in Steel-making Process of Panzhihua Iron and Steel Corporation

To solve potential scheduling problems in production after renewal of continuous casting process in Vanadium-extracting and Steel-making Plant of Panzhihua Iron and Steel Corporation (PISCO), how to model and simulate logistics system in steel-making processhas been discussed. A series of simulatingtests for logistics system in steel-making processhave been conducted based on inputs of presentsteel-making processof PISCO. In the tests, cases of regular schedule case and cases with repairing converter have also been regarded as essential simulation condition. It has been shown that three casters can not start at same time in order to ensure continuous hot metal supply for casters when three kinds of steel are made. It has also been shown that the simulation system for logistics system in steel-making processis valid and can be used for simulating logisticsin upcoming 100% continuous casting process of PISCO. The better schedule scheme of production and reasonable match of converter-caster in time and capacity can be achieved with the help of using simulation approach.     

Heat Transfer Characteristics of the Melting Process of the Metal Foam/Paraffin Compound Material

In order to enhance the heat transfer in the phase change heat storage device, a rectangular cavity filled with metal foam / paraffin wax is made. The melting heat storage experiment of foam metal / wax composite phase change material was carried out in the transverse wall temperature conditions. The temperature change curve is drawn according to different heating temperatures. Both the effects of natural convection in rectangular cavity on temperature distribution and the impact of heat transfer temperature difference on the thermal storage time are analyzed. The results show that the melting process of the paraffin in the body cavity is reinforced by the high thermal conductivity of copper foam. The remaining solid paraffin is accelerated to melt by the natural convection of the liquid paraffin formed near the heating surface; and the greater the heat transfer temperature difference is, the greater the natural convection is and the shorter the time for heat storage is.     

Analysis on Refining the ZLD11 Nuclear

The ZLD11 alloys containing Sr have been prepared by adding AlSr master alloy and the refinement effect of Sr on the microstructure are investigated with different contents of Sr in the finish alloys such as 0.04%,0.06%,0.08%and 0.10% Sr to change the grain size of ZLD11 alloy in mass, both microstouctve observation and gain size statistical analysis have been used to discover the proper additions of Sr. The effects of the main alloying elements on properties of ZLD11 alloy, as well as the smelting process are introduced. The results indicate that AlSr master alloy as a crystal refiner with X metal mold casting process has an effective grain refinement for ZLD11 alloy, the best refinement effect were obtained with addition of 0.08% Sr.     

改良剂对锑矿区土壤锑形态和生物可利用性影响的研究

利用人工造林结合应用土壤改良剂的试验,研究了土壤改良剂对重金属锑的形态差异、分布特征和生物可利用性的影响,为锑矿区重金属污染土壤生态修复提供技术依据。结果表明：随着土壤改良剂施放量的增加,土壤的pH值增加,当每株施放改良剂达300 g时,土壤pH值由酸性变为弱碱性。不同剂量的土壤改良剂对0~20 cm、40~60 cm土层Sb的碳酸盐结合态有显著影响,对20~40 cm土层Sb的碳酸盐结合态有极显著影响;对40~60cm土层Sb的残渣态有极显著影响。锑矿区土壤0~20 cm土层中Sb的形态以铁锰氧化态、有机物结合态、残渣态形式存在,20~40 cm土层中Sb的形态以铁锰氧化态、有机物结合态、残渣态形式存在,40~60 cm土层中Sb的形态主要以有机物结合态、铁锰氧化态形式存在。施用改良剂可增加Sb的生物可利用态18.92%~24.23%,降低Sb的生物潜在可利用态17.55%~18.92%,降低Sb的不可利用态0.95%~6.03%,显著增加了Sb的生物活性,增加了Sb的生物有效性,增加了重金属Sb的生态风险,此时Sb易于被植物吸收并进入植物体,对植物产生一定的毒害作用。锑矿区土壤0～20cm土层中Sb的形态以铁锰氧化态、有机物结合态、残渣态形式存在,20～40cm土层中Sb的形态以铁锰氧化态、有机物结合态、残渣态形式存在,40～60cm土层中Sb的形态主要以有机物结合态、铁锰氧化态形式存在。施用改良剂可增加Sb的生物可利用态18.92%～24.23%,降低Sb的生物潜在可利用态17.55%～18.92%,降低Sb的不可利用态0.95%～6.03%,显著增加了Sb的生物活性,增加了Sb的生物有效性,增加了重金属Sb的生态风险,此时Sb易于被植物吸收并进入植物体,对植物产生一定的毒害作用。     

Experimental Study of Flow and Heat Transfer in Heat Exchanger with Small Channels

The experimental study of the flow resistance and heat transfer characteristics are conducted for water and ethylene glycol solution (66% Wt) flowing in the heat exchanger with small rectangular microchannels . The heat exchanger having the channels of 0.4 mm in width, 2.0 mm in height, and 20 mm in length is heated by a hearing rod at the bottom surface, the upper and two side surfaces are adiabatic. During experiments, the Reynolds number are ranged from 2 to 2 500. The experimental results show that the flow friction factor decreases and Nusselt number increases with increasing Reynolds number for water and ethylene glycol solution. At a fixed Reynolds number, the Nusselt number for ethylene glycol solution with larger Prandtl number is greater than that for water. Meanwhile, the correlations of flow resistance and heat transfer in the heat exchanger with small channels are obtained for engineering application.     

Development of Heat Flow Meter and Research on Amelioration of International Advanced Technique

Heat flow meter is an apparatus measuring the transfer of heat energy. In developed countries it is used in detection of energy consumption and safety system of electricity generation, steel making, chemical engineering and building heating and air-conditioning, but it is just a start for its application in China. The research of heat flow meter with own intellectual property is based on the urgent need of energy saving in China. The innovational research must be based on improvement of current technique. In this paper, the progress of heat flow meter is reviewed and the sort and principle of heat flow meter is introduced. The best feeler and the crucial technique of thermopile for heat flow meter in thermal resistance are selected. The disadvantage and ameliorative method is pointed out. At last, a Chinese patent is granted to the authors.     

Effect of B2O3 on the physico-chemical properties of mold slag used for high-Al steel

A new mold slag with low content SiO2 and high content Al2O3 is designed in order to avoid or alleviate the reaction between Al and SiO2 during the continuous casting of high-Al steel, the acidity of this slag is adjusted by adding B2O3, and the effect of B2O3 content on the fusion property, viscosity property and heat transfer characteristics through the mold slag film of the mold slag is analyzed. The results show that the fusion temperature, viscosity, viscous flow activation energy decrease and heat flux through the slag film increases with the increase of B2O3 content in the range of 4%~10%; temperature time transformation (TTT) diagrams move to longer incubation time with the increase of B2O3, while the crystallization speed of mold fluxes decreases; under this experiment condition, the precipitation of CaF2 crystals can be restrained by the increase of B2O3 content in the mold slag.     

Analysis of Heat Transfer and Optimal Parameters of Multi-louvered Fin Condenser

The authors conduct the experimental study and optimal computing for the condenser of automobile air conditioner. The especially the properties of heat transfer and flow at the side of air when using shutter fin. The authors the influence of several combinations of fin's geometry parameter to heat transfer and flow resistance. The maximal heat transfer is used as a criterion relation to select the fin's geometry parameters in the same facing air area of condenser. Furthermore, a program is designed to conduct optimal computing, and the computing results are basically consistent with experimental results. It shows that the optimal method is reasonable and the results can be applied to engineering practice.     

Modeling and realizing of integrated batch planning for steelmaking-continuous casting and hot strip rolling

An integrated batch planning mathematical model based on multi-object optimization is proposed to solve the orderly and efficient flow of material between different working stations in iron and steel enterprises, where production technology constraints, material variations and coupling between steelmaking-continuous casting and hot rolling are analyzed first. According to the requirements of the hot rolling steel strip contracts, the integrated batch planning is divided into sub-plans of rolling plan, casting plan and furnace plan which are independent and coupling to each other, forming rolling plan and furnace plan simultaneously to influence casting plan. Heuristic method based on modified co-evolutionary algorithm is advanced to resolve this problem. The results of simulation and analysis in an iron and steel plant for strip steel production shows that it is feasible to provide effective guidance for integrated batch plan making.     

Dealing with Thermal Exchange in Temperature Field Simulation in Low Pressure Die-casting Process

The main effort is to develop numerical simulation software of low pressure die casting on Windows platform in Personal Computer, based on the production of aluminum wheel in Die cast wheel manufacture Co. Ltd.. The heat conduction calculation is the basis of solidification simulation. A 3 dimentional model including the refrigeration medium block is set up based on the study of boundary heat exchange. Various calculation method is analyzed for different types of boundary element. A comprehensive calculation model is set up according to practically manipulable parameters in production.