共查询到19条相似文献,搜索用时 750 毫秒
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矾土水泥混凝土预制坩埚用于工频无心炉熔炼铝及铝合金舒克炎青岛崂山电炉厂我国在铸造行业中对于铝及铝合金的熔化,在60年代至80年代初,主要采用电阻炉,到了80年代初以后,逐渐被无心工频炉所代替。但到目前为止,在无心工频炉上熔化铝及铝合金主要是使用铁坩埚... 相似文献
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目前,铝合金残料均在火焰炉或感应炉里熔炼,由于感应炉熔炼时热量产生在被加热料的内部,能充分利用热量,且金属的搅拌剧烈,加热速度快。当金属的外表面被加热后,通过传热使内表面也被加热。因此,感应炉是熔炼铝合金废料的理想设备。 相似文献
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本文简要地介绍了活塞用共晶铝—硅合金中各元素的主要作用和合金的熔炼特性与传统熔炼工艺的不足;重点论述了低温加硅、磷变质和一次熔炼工艺的确定以及低温加硅的机理;简述了活塞用共晶铝—硅合金采用磷变质的优点;最后简结了低温加硅、一次熔炼工艺的主要优点。 相似文献
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铝液中存在夹杂物,会导致铝合金铸件的机械性能下降,刀具磨损加剧,疏松现象多,表面粗糙度差,气密性降低.夹杂物一直被认为是影响铸件质量的主要因素.在铝合金熔炼、处理过程中,重视采用对夹杂物的检测、分离和控制技术,是生产优质铸件的关键. 相似文献
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提出考虑煤灰各成分熔融温度与煤灰化学成分含量的统计分析判别方法及神经网络判别方法.对170多种中国煤质采用2种方法的计算结果与实验数值的比较结果表明,使用统计分析能将煤灰熔融温度的计算命准率提高到80%以上,使用神经网络方法的命准率达100%,且均不需要将煤质分类判别.提高判别方法命准率的核心机理是:煤灰的结渣特性主要取决于煤灰中各化学成分的百分比含量,同时也取决于各物质的熔点温度.这一机理与很多电站锅炉通过掺烧高灰熔点煤降低结渣程度的实际运行事实和试验结果相吻合,提高了各种煤质的结渣特性判别的通用性和命准率.神经网络方法具有智能优化的特点,比统计分析方法更具有普适性和高命准率. 相似文献
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分析提出了工频有心感应炉熔沟起熔送电的指导原则,通过模拟计算确定了该厂45t熔锌炉熔沟起熔送压方案。 相似文献
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A finite-volume model is used to analyze alternate melting and solidification, which is the fundamental operational mode of latent thermal energy storage (LTES) systems. The simulated cases include: (1) melting of tin with natural convection, (2) alternate melting and solidification of sodium nitrate, and (3) cyclic phase change of gallium. For each case, temporal evolution of the heat transfer rate and liquid fraction is presented. In addition, snapshots of phase interface, temperature, pressure, and liquid velocity distributions are presented. The implications of the modeling results are discussed. 相似文献
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A one-dimensional time-dependent heat transfer model is presented for the melting process in a circular scrap melter. The phase change problem is tackled using an enthalpy-based method, and the complex scrap geometry is described with the porosity concept, i.e., the blocking effect of the scrap is represented by a blocking factor that is a function of the scrap porosity. Flame length is represented by a flame damping factor. The numerical procedure is carried out in three stages, from initial heating to complete melting. Some typical cases are simulated. Results show that the flame damping factor can significantly influence the melting process. A lower damping factor gives better uniformity in metal temperature distribution. The melting time can be improved drastically by decreasing this factor. The convective heat transfer coefficient dominates the temperature profile. The higher the convective heat transfer, the faster the temperature increase in the lower part of the furnace. A long flame and good stirring of the melt enhance the melting process. 相似文献
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随着我国社会经济的发展,城市垃圾的产量快速上升。采用等离子体气化熔融技术来处理城市垃圾,能避免传统处理方式带来的二次污染问题,但由于我国城市垃圾含水量高、热值低等原因会造成等离子体炬电耗高的问题。本文结合气化熔融技术、回转式预热器、蓄热式燃烧以及余热回收等多项先进技术,理论上设计了一套日处理垃圾能力在10 ~ 30 t的等离子体气化熔融/垃圾处理系统。系统的减容率在95%以上,在充分利用垃圾中的能源的同时,将二噁英的排放控制在国家标准0.1 ng-TEQ/Nm3以内,减少重金属等二次污染物的排放,具有良好的经济性和环保性。 相似文献
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1 前言随着市场需求的不断更新 ,内燃机不断地向高转速、高寿命、低能耗和低排放的方向发展 ,这样势必对其主要零部件—缸套的技术含量提出更高的要求。缸套的机械性能必须在原来的基础上提高 2 0 %以上 ,抗拉强度要≥ 2 60 MPa。目前内燃机在使用寿命和抗磨损能力方面均已提出更高的指标 ,必须要达到 5 0万公里的指标 ;对缸套的几何尺寸、形位公差在原 IT7级的基础上提高到 IT6级 ;对平台网纹的质量要求越来越高。这样才能保证发动机尾气排放达标。总之 ,内燃机技术的发展 ,完全是建立在主要零部件性能和寿命的不断改进基础上的。缸套… 相似文献
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Melting and dynamic-surface deformation in laser surface heating 总被引:1,自引:0,他引:1
Bok-Cheol Sim 《International Journal of Heat and Mass Transfer》2005,48(6):1137-1144
Axisymmetric thermocapillary convection during laser melting has been investigated numerically. The dynamic free surface, with pinned contact point at the edge of the molten pool, is obtained as a solution of the coupled transport equations. Free surfaces at the steady state are depressed at the center and convex near the edge of the molten pool because fluid flows away from the center. The surface deformations decrease with increasing Re at fixed Ca, while they increase with increasing Ca at fixed Re. The width and depth of the pool, temperature and surface deformation increase with increasing Bf. At the transient cases, the size of the pool and surface deformation increase monotonically with time. The shape of the free surface is a bowl bump at a low Re, while at a high Re two kinds of surface shapes occur with time: bowl and Sombrero-shaped bumps. 相似文献