矿热炉炉衬结构的温度场分析

为进一步研究矿热炉炉衬中温度场的分布情况,采用ANSYS仿真软件对真实简化的炉衬模型进行仿真分析。通过改变炉内温度和对流换热系数的数值,得到炉壁处的温度数据,与实测数据进行对比,验证模拟数据的合理性。结果表明,炉衬中不同耐火材料的温度分布存在差异;炉壁温度会随着炉内温度的增大而逐渐升高,随着对流换热系数的增大而降低;炉壁温度随对流换热系数的变化曲线斜率从0.13降到0.06,当曲线斜率逼近于0时,对流换热系数不再影响炉壁温度的变化,得到最优化的对流换热系数;模拟数据占实测数据的百分比在3%~8%范围内时,模拟数据能合理反映炉壁温度值。这为炉体保温结构设计和耐火材料的选用提供依据。     

高温竖窑燃烧状况的CFD模拟

采用Fluent软件对高温竖窑内部燃烧状况进行了模拟计算,分析了燃气喷枪偏转角度、布置方式、热负荷等参数对窑内燃烧状况的影响规律。结果表明:燃气进口偏转角度对窑内温度场的影响比较明显,当0°α5°时,温度场分布有所改善,再增大角度,导致中心温度明显降低;增产时,热负荷、一次空气量及冷却空气量同比例增大,窑内温度场变化不大;采用双层交错排列使得热量相对分散,温度分布更为均匀。     

新型螺旋翅片管对流换热系数的研究

采用数值计算的方法，自行设计螺旋翅片管温度场计算软件，并利用其计算结果讨论了管内壁和外壁对流换热系数的变化规律，及管内外热阻的匹配问题。数值计算结果表明，管内换热系数随温度的升高而升高，管内空气和管外烟气的流速分别显著影响管内管外换热系数。翅片管的外形尺寸同样影响到螺旋翅片管的温度分布。     

辽西钒钛磁铁矿焙烧回转窑内气固传热数值模拟

在对钒钛磁铁矿焙烧回转窑的传热过程及物料运动行为进行研究的基础上,建立了钒钛磁铁矿焙烧回转窑温度分布数学模型。并应用数值计算方法对该模型进行求解,得到了中试回转窑内物料和烟气沿轴向的温度分布。结果表明:物料在刚进入回转窑时被迅速加热,随后升温速率减慢;当烟气温度较低时,对流换热系数为20 W/(m·K)左右,为辐射换热2倍;随着烟气温度升高,辐射换热成为主要机制,在窑尾处可达对流换热10倍左右;对于中试回转窑,数值计算模型与实验结果误差最高为50 K,具有较高的准确性,可指导生产中回转窑设备的优化。     

基于中型回转窑焙烧试验的温度场分布研究

基于中型回转窑焙烧试验,对液化石油气燃烧性能和回转窑传热进行了分析,根据窑内窑头、窑中和窑尾温度,利用Fluent软件从轴向和径向进行了温度场分布分析,直观地了解窑内温度分布情况。通过对窑内温度曲线进行拟合,得到窑内温度梯度方程为Tx=-0.07188 X+B。     

水泥回转窑温度分布研究

考虑了回转窑煤粉燃烧和窑内化学反应,建立了计算回转窑温度分布的综合数学模型,并对标准工况的编程求解,计算出烟气、物料、窑内壁和窑筒体外表面温度分布,对物料温度分布进了分析.将计算所得的窑筒体外表面温度分布与实测值相比较,两者具有较好的一致性,验证了所建立的回转窑温度场计算模型的有效性,为优化回转窑内的热工状况提供依据.     

带钢层流冷却过程中冲击穿透深度的数值模拟

带钢在层流冷却过程中距表面较近的区域温度存在反复升降的现象,造成厚度方向上组织和性能的差异。结合酒钢CSP热轧带钢生产数据,建立一维热轧带钢有限元模型,计算层流冷却过程中带钢的温度场。提出了冷却过程中带钢冲击穿透深度的概念,并初步探究其影响因素。厚度为3和4mm的带钢计算得出的卷取温度比实测温度分别高3和8℃,相对误差分别为0.44%和1.16%,验证了模型和假设的合理性。结果表明,冷却过程中冲击穿透深度受带钢的导热系数、平流区的对流换热系数、带钢表面温度和喷嘴分布的影响;带钢上表面喷嘴分布较少,冲击穿透深度随对流换热系数的增大而增加,下表面喷嘴分布密集起主导作用,增加对流换热系数,冲击穿透深度几乎不受影响。     

回转窑无管供风煅烧技术的探讨

以φ2.3x55 m的炭素回转窑作为研究对象,对回转窑内的煅烧过程进行了数值计算.通过多次改变二、三次供风管的长度,得到了相应条件下窑内的温度分布,并进行了比较和分析.结果表明:二、三次供风管的长度对窑内温度场的影响较小,实践中可以采用无管供风措施,以解决供风管道烧损问题.     

氧化铝熟料窑内一维传热模型

综合考虑烟气、窑壁和料床间的传导、对流和辐射传热，建立了氧化铝熟料窑内一维传热模型。应用龙格库塔方法，预测熟料窑任一横剖面气体和物料的温度，对封闭的回转窑内高温烟气和低温物料逆向传热规律以及窑内各带温度分布的合理性进行研究，分析了生料掺煤量对窑内温度分布的影响。结果表明，控制合适的生料掺煤量，可得到合理的燃烧带温度和各带的长度分布，延长回转窑的使用寿命。本模型实用性强，适用于现场对封闭回转窑内气体和物料温度的预测和参数的优化。     

棒材穿水冷却温度场研究与工程应用

针对棒材穿水冷却过程,建立了棒材温度场数学模型。同时提出了对流换热系数公式并对其参数进行了优化,该温度场数学模型的仿真结果与实测值相吻合,能够准确地预测棒材穿水冷却过程的温度分布。采用棒材温度场数学模型可以计算轧钢车间水箱布置数量及恢复段的长度,为优化控冷工艺及轧钢车间工艺布置提供计算依据。     

H型钢炉内加热过程温度应力耦合数值模拟研究

采用有限元计算中的间接法,对H型钢在加热炉内的加热过程进行二维耦合求解分析,求解温度场时分别计算H型钢的对流及辐射热流,而后代入Ansys有限元软件进行求解,求解应力场时以温度场计算结果为初始条件。分别计算了不同热负荷下H型钢温度场及应力场的变化状况,得到了H型钢炉内加热过程温度场及应力场的变化规律,为H型钢的加热控制提供了理论依据。     

高速线材轧制全程温度曲线有限元模拟

采用Deform模拟计算加热炉铸坯温度分布,并通过‘黑匣子’试验验证,当加热时间为70 min时,铸坯心部与表面温差约66℃,80 min时降到15℃.模拟计算轧制和水冷过程心部和表面温度曲线,并通过测温仪验证,得出准确的摩擦热、塑性变形热以及水冷换热系数模型.采用Fluent模拟计算风机的风场,使用手持测风仪验证,再建立盘条搭接点温度模型,计算出风冷线上强迫对流换热、自然换热和辐射换热系数以及相变潜热,使用热成像仪测温验证.模拟与试验结果十分吻合.      

Numerical Analysis of Heat Transfer Characteristics in Microwave Heating of Magnetic Dielectrics

A numerical simulation of heat transfer during the microwave heating process of magnetite, which is a two-dimensional (2-D) magnetic dielectric, subjected to heat conduction, convection, and radiation was performed. The heat transfer process was modeled using an explicit finite-difference approach, and the temperature profiles for different heating parameters were generated through developing a code in Mathematica 7.0 (Wolfram Research, Inc., Champaign, IL). The temperature in the sample increases rapidly in 1 minute and nonuniform temperature distribution inside the object is observed. An obvious temperature hot spot is formed in the corner of the predicted temperature profile initially, which shifts to the center of the object as heating power increases. Microwave heating at 915 MHz exhibits better heating uniformity than 2450 MHz mainly because of the larger microwave penetration depth. It is also observed that the heating homogeneity in the object can be improved by reducing the dimension of object. The effects of heating time, microwave power, microwave frequency, and object dimension need to be considered to obtain high heating performance and avoid/minimize thermal runaway resulting from temperature nonuniformity in large-scale microwave heating.     

快速对流加热技术及其在锻造炉中的应用

对快速对流加热的热工新技术进行了系统介绍,分析了具有代表性的金属冲击加热、强制循环对流加热、对流脉冲加热技术的传热特点与节能降耗、改善加热质量的实践效果,还指出了应用过程中应注意的问题.     

Neuroleptic malignant syndrome: a review

Experiments were performed in a tissue microwave-equivalent phantom gel to quantitatively examine the volumetric heating produced by a microwave antenna with a peripheral cooling system for the transurethral prostatic thermotherapy. Based on previous research, expression for the specific absorption rate (SAR) of microwave energy in the gel was extended to three dimensions, which includes its dependence on radial, angular, and axial direction. A theoretical heat transfer model was developed to study the temperature distribution in the gel by introducing this proposed SAR expression. The parameters in this expression and the convection coefficient due to the chilled water running around the antenna were determined using a least-square residual fit of the theoretical temperature predictions to the experimentally measured steady-state temperature field within the gel. The analytical expression of the three-dimensional SAR distribution obtained in this study will help provide a better understanding of the microwave heating pattern in the prostatic tissue and, thus, to aid in designing improved applicators. It can also be used in the future as an accurate input to heat transfer models which predict temperature distributions during the transurethral microwave thermotherapy.     

漆包线热解炉反应器的数值模拟与优化设计

铜漆包线是重要的二次铜资源,回收过程中表面有机漆层的脱除主要依靠热解,热解炉内的不均加热将导致漆层脱除不完全或铜线表面氧化。以某铜漆包线热解炉为研究对象,通过数值模拟的方法对热解炉内燃烧及传热过程进行计算,并根据模拟结果进行了结构优化：使用EDM燃烧模型模拟甲烷燃烧产生热量,得到炉内高温气流的温度场分布及气流流向,发现炉内存在流动死区及罐体加热不均匀问题。根据计算所得流场及温度场对炉膛结构设计进行优化,增加导流挡板及更改出口位置等,增加热解罐受热面积,解决罐体加热不均问题,提升温度均匀性约58%,可提前20 min达到热解所需温度,在工业生产中可以节省耗气量。     

Sintering of a highly heat-resistant ceramics by using combination SHF-heating and equipment for its realization

This article examines the main problems in sintering a highly heat-resistant ceramics by SHF heating. It is shown that it is expedient to use combination heating from an SHF source and additional heaters made of resistive composites to speed up sintering and equalize the temperature distribution in the ceramics. The additional heaters heat the product externally by convection and radiation. The synthesis of mullite from powders obtained by the sol-gel method and gradient powders of Al₂O₃/SiO₂ is described to illustrate the use of combinated SHF heating.     

The Influence of Oxide Scale on Heat Transfer during Reheating of Steel

The present work presents methodology and development of a mathematical model for prediction of the influence of oxide scale on heat transfer during reheating of steel in an industrial furnace. In this developed model, temperatures inside the steel billet were measured and with thermocouples at selected places and were collected by a water cooled computer that was traveling inside the slab. CFD is used to calculate the flow field inside of a furnace. The mass‐transfer coefficient of the scale formation is obtained by solving the convection mass‐diffusion equation across a boundary layer to the surface of a flat plate. A model for inverse heat conduction is employed to calculate the local surface temperature and heat flux on top of the growing oxide scale layer on a slab moving through a walking beam reheating furnace. By using the inverse method, the transient temperature and heat flux was firstly determined on the surface of the steel. During subsequent computations, the growth of the scale was calculated and the surface temperature of the oxide scale was extracted by using the Cauchy data from the previous calculations. The sensibility of the model on steel physical parameters is studied, and suitable parameters were obtained for heating a low carbon steel plate in the reheating furnace. Results show that the oxide scale layer should not be neglected in reheating models.     

连铸机辊子与铸坯传热的研究

根据连铸机辊子的实际工作情况，将其内外表面分成传导传热区，对流换热区和辐射－对流综合换热区。利用距辊子表面３ｍｍ处所测得的温度变化曲线，通过辊子换热的平衡方程，推导出每一区域的综合传热系数及其表面温度的表达式，为正确计算辊子的温度场，供应力提供了较为可靠的依据。     

低温共烧陶瓷专用烧结炉温度场的数学模型

文章利用传热学的知识结合低温共烧陶瓷（LTCC）专用烧结炉炉内辐射与强制对流综合传热的特点，建立了烧结炉温度场的数学模型，从而为烧结炉温度场的全局数值模拟奠定基础。