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本文对某裂解气急冷换热器内孔焊接过程进行了详细的阐述,此种操作方法应用于生产后,可提高产品合格率,降低焊后返修率,并大大缩短了生产周期,本文可为同行业生产类似产品提供一定参考. 相似文献
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通过CFD软件模拟了单个共晶盐蓄冷球在蓄冷槽中的凝固过程.在整个充冷过程中蓄冷球表面与外围载冷剂流场换热直至完全凝固.模拟中发现,由于整个流场的流速较低,蓄冷球凝固初始阶段球表面的自然对流对流场的影响不可忽视,同样也影响球体本身的热通量.模拟结果表明蓄冷球在负向流动流场中所需的凝固时间小于正向的凝固时间. 相似文献
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介绍了湿法烟气脱硫系统吸收塔的结构特点,并对某项目燃用设计煤种时不同负荷条件下吸收塔内烟气流场的分布进行了模拟研究和分析。验证了该项目吸收塔设计的合理性及实际运行时对负荷的适应性,为吸收塔的优化设计和稳定运行奠定了理论基础。 相似文献
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本文针对某燃气轮机环管型燃烧室三维冷态流场的数值模拟问题进行了研究。根据该型燃气轮机燃烧室的设计图纸建立真实的三维计算几何模型;在计算中采用SIMPLE算法,k-ε双方程湍流模型,对其进行了冷态空气流场的数值模拟;通过对各处流场分布的分析,特别是对主要区域各关键截面的流动分析,可以判断出燃烧室设计的合理性,为进一步优化燃烧室的结构设计、改善流场结构,并为开展燃烧室热态流场的数值模拟奠定了基础。 相似文献
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本文针对烟气脱硫装置中各塔(急冷塔或反应塔)内的烟气流场进行数值模拟,通过改变急冷塔的入口结构以及扩散叶片结构,或改变反应塔下部文丘里管渐扩口角度以及加装整流小管,得到了较为均匀的烟气流场结构。 相似文献
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直接空冷机组喷淋冷却系统的数值模拟和性能分析 总被引:1,自引:0,他引:1
以国产某300 MW直接空冷机组为例,建立了空冷单元喷淋冷却系统的数值分析模型,设计了3种不同型式的喷淋冷却系统,并采用Fluent软件对喷淋冷却系统的性能进行了数值模拟,得到了空冷单元内部及出口的温度场.结果表明:喷淋后空冷单元的出口空气平均温度比喷淋前降低了2~5 K,其中加装喷淋系统C后的空冷单元出口空气平均温度降低了5 K,排汽压力降低了6.7 kPa;喷淋系统的喷雾越均匀,雾滴覆盖范围越大,喷淋冷却系统的性能越好,排汽压力的降幅越大,经济性越好;对于国产某300 MW机组,当除盐水量充足时,采用喷淋系统C是最佳方案,如除盐水量有限,则应选择喷淋系统B. 相似文献
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Recent studies of J.H. Song et al. [1], and S.Y. Yang et al. [2] (see also references therein) have been concentrated on mitigation measures against hydrogen risk. The authors have proposed installation of quenching meshes between compartments or around the essential equipment in order to contain hydrogen flames. Preliminary tests were conducted which demonstrated the possibility of flame extinction using metallic meshes of specific size.Considerable amount of numerical and theoretical work on flame quenching phenomenon has been performed in the second half of the last century and several techniques and models have been proposed to predict the quenching phenomenon of the laminar flame system (see for example [3] and references therein). Most of these models appreciated the importance of heat loss to the surroundings as a primary cause of extinguishment, in particular, the heat transfer by conduction to the containing wall. The supporting simulations predict flame-quenching structure either between parallel plates (quenching distance) or inside a tube of a certain diameter (quenching diameter).In the present study the flame quenching is investigated assuming the laminar hydrogen flame propagating towards a quenching mesh using two-dimensional configuration and the earlier developed models. It is shown that due to a heat loss to a metallic grid the flame can be quenched numerically. 相似文献
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Direct numerical simulation is performed for quenching of a hot plate in liquid jet impingement. The flow and thermal characteristics associated with the quenching process, which includes film boiling in the fluid region as well as transient conduction in the solid region, are investigated by solving the conservation equations of mass, momentum and energy in the liquid, gas and solid phases. The liquid–vapor and liquid–air interfaces are tracked by the sharp-interface level-set method modified to treat the effect of phase change. The computations demonstrate that the boiling curve of wall heat flux versus temperature does not depend on the transient or steady-state heating conditions. The effects of initial solid temperature and solid properties on the quenching characteristics are quantified. 相似文献
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An integrated numerical model was applied to simulate the mold filling and solidification process as well as predict the occurrence of relative casting defects for a rotor hub casting. The goal was to conduct a numerical experimentation to obtain an optimal alloy design of ductile cast iron for the rotor hub casting. A computer‐aided engineering software based on the finite element method was employed in this study. Numerical simulations were conducted for the rotor hub casting with two different types of alloy composition for ductile cast iron. The mold filling and solidification process were examined to predict the occurrence and extent of casting defects and a better alloy design was then proposed based on the simulated results to alleviate casting defects of the rotor hub casting. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Dehong XIA Gang ZHANG Liang GUO Department of Thermal Engineering University of Science Technology Beijing Beijing China Professor 《热科学学报(英文版)》2006,15(3):269-273
The thermal process of L.M.Pidgeon's reduction art,widely used in magnesium production,is numericallysimulated.It is shown that the thermal efficiency will be highly enhanced with the increase of heat-exchange areaor the intensification of heat exchange between flame and the outer surface of the reduction jars.An innovationhas been made by fuel-shifting(from coal to Coal-Water Mixture),up-draft reduction furnace configuration,multi-layer jars installation and waste heat recovery.A bench scale furnace has been constructed and put intooperation to identify the simulation and new design. 相似文献
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通过建立热管的简化热阻模型,采用数值计算的方法模拟了热管的动态蓄冰。模拟结果与实验结果吻合。同时,对热管冷凝段和蒸发段的长度比为1:2和1:4两种形式进行了数值模拟比较。结果表明,1:4的布置形式更优。 相似文献
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本文通过数值模拟的方法分析了掺烧印尼煤时炉膛内的燃烧特性和结渣特性,研究了印尼煤在不同掺混比例下对炉膛结渣的影响,试验结果表明:掺烧一定量的印尼煤有利于改善炉膛内的结渣特性,印尼煤灰熔点较低,与高热值基础煤掺混时容易产生结渣,掺烧比例不宜过大,基础煤与印尼3进行混配的最优推荐比例为5∶1。 相似文献
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To simulate the ice accretion on an airfoil, a boundary moving technique is proposed to deal with the distortion of the airfoil surface due to ice accretion on the leading edge. Incorporating the two‐phase model of air‐supercooled droplets in the Eulerian coordinate system, this technique is applied to simulate the process of the rime ice accretion (the droplets freeze at the instant impinging on the airfoil) on the NACA 0012 airfoil, and the ice profile after ice accretion is achieved successfully. A brief comparison between the results of this paper and the experiment data indicates that the current method is applicable and effective. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(4): 226–234, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20064 相似文献