共查询到20条相似文献,搜索用时 171 毫秒
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《电力信息与通信技术》2015,(12)
对于光纤复合架空地线(Optical Fiber Composite Overhead Ground Wire,OPGW)线路实施融冰,目前多采用直流融冰技术,主要是对OPGW架设方式进行绝缘化改造,但在实际应用中仍有许多无法避免的缺陷。为了进一步解决OPGW融冰的技术性问题,文章介绍了一种具有可通流融冰功能的光纤复合架空地线设计方案和应用方法,并在实验室及现场覆冰试验站进行了实际融冰试验,在实际覆冰条件下,试验验证了全绝缘和内嵌式融冰的实际融冰电流、融冰时间和融冰时对缆中光纤的温度影响。结果表明,该结构可融冰OPGW融冰效果良好,满足线路融冰要求。 相似文献
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旨在制备适合复合绝缘子的光热涂料以解决其冬季覆冰问题。测量了光热涂层吸收率与发射率,分析了光热涂层融冰过程,建立光热型复合绝缘子融冰模型,并对其温升情况进行仿真;进行了带电融冰试验,探究不同太阳光照强度及环境温度对光热涂层融冰效果的影响。仿真及人工模拟试验结果表明:该光热型融冰涂料具有良好的光热性能;涂覆光热涂层的复合绝缘子具有一定的融冰效果,融冰效果随太阳光照强度与环境温度的升高而加强。 相似文献
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《电力信息与通信技术》2015,(9)
为了解决现行的OPGW融冰方式的一些不足,文章研制了一种可融冰OPGW,可融冰OPGW的安装方式可采用常规的逐塔接地方式,不需要对OPGW进行"绝缘化"架设。在覆冰季节,可在不停电的情况下对可融冰OPGW内的绝缘导线施加较大电流进行加热,达到融冰的效果;也可长期对绝缘导线通较小电流,使OPGW的温度保持在零度以上,避免覆冰,达到"保线"的目的。 相似文献
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超高压输电线路运行中线路覆冰会极大的提升电力系统故障几率。如果人工除冰不仅工作量大,需要投入大量人、财、物,并且还需要高空作业,风险较高。这就需要采用超高压输电线路自融策略,如保线电流法、三相短路融冰法、直流融冰法等。其中,直流融冰法更适用于超高压输电线路。基于此,本文就针对超高压输电线直流融冰技术展开进一步分析。 相似文献
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通过与常规导线对比,详细分析了耐热导线——碳纤维芯耐热(铝绞)导线的机械电气性能。同时,分析指出了750kV大截面、大容量输电线路的特点。在此基础上,探讨了碳纤维芯耐热导线在750kV线路上应用的可能,并进一步分析了碳纤维芯耐热导线的应用对750kV线路工程的影响。最后总结了耐热导线技术发展的方向和应用前景。 相似文献
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为准确评估不同弯曲状态下导线分层应力特性,以LGJ500/45型钢芯铝绞线为研究对象,考虑张力作用下各层股线的轴向应变和轴向扭矩,提出输电线路精细化分层张力、分层应力应变的计算方法,通过建立并模拟不同弯曲角度(0°、15°)的三维导线分层有限元实体模型,对比了理论计算结果,验证了仿真模型的准确性,得出不同弯曲状态下运行张力作用时导线各层间的应力分布规律。结果表明,0°导线在承受轴向张力的作用下,两层钢芯线承担主要张力,且各层钢绞线和各层铝绞线均呈由内至外轴向逐渐增大的趋势;15°弯曲导线分别出现弯曲朝向侧圆周方向应力更高、反方向圆周方向应力更低等导线分层力学特性。 相似文献
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相变储能材料由于其具有周期性储存和释放能量的特点,在电池热管理、太阳能发电等领域存在着广泛的应用。然而由于导热系数低的原因限制了其进一步的应用。高导热率泡沫材料的添加为解决这一不足提供了一种有效的方法。文章采用三周期性极小曲面(TPMS)生成泡沫铝骨架,基于孔隙尺度数值模拟了铝/石蜡复合相变材料相变蓄热的变化规律。结果表明:铝骨架的添加强化了蓄热,缩短了融化时间,在复合相变材料孔隙率为0.90、0.85、0.80时,相比于纯石蜡,完全融化时复合相变材料的融化时长分别缩短了68%、75%和80%,而且蓄热过程中温度场更加均匀;验证了铝骨架与石蜡之间由于热导率存在较大的差异,存在的热非平衡效应,且铝/石蜡复合相变材料孔隙率越低,此效应越明显 相似文献
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基于碳纤维复合芯导线所具有的优点,运用数值模拟方法建立了碳纤维复合芯导线和传统钢芯铝绞线输电塔体系三维有限元模型,采用时程分析法,考虑了导(地)线的几何非线性,研究了一致激励和非一致激励地震作用下导(地)线输电塔体系的地震响应,得到了两种塔—线体系的塔顶位移和加速度、塔腿应力、导线中点最大位移和加速度、导线轴力的时程曲线。结果表明,碳纤维复合芯导线—输电塔体系与钢芯铝绞线—输电塔体系相比,塔顶最大位移、塔腿应力、导线中点最大位移和加速度均较小,一致激励地震作用与非一致激励地震作用的地震响应相差较大,非一致激励地震作用下比一致激励地震作用下的导线中点和挂点轴力大。 相似文献
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Ishant Jain 《亚洲传热研究》2017,46(2):111-133
The strength in a high carbon wire is attributed to the pearlitic microstructure, which is required for ease of wire drawing. During cold drawing of high carbon steel wires, residual stress develops which has to be relieved in order to obtain the desired mechanical properties. To achieve this, the wire is passed through a closed loop online an induction furnace at a particular speed in order to heat it to a uniform temperature range. This research work presents the electromagnetic‐thermal modeling of the induction heating of a moving wire based on the finite element method using the software package, COMSOL MultiphysicsTM. The furnace had a complicated geometry for the coils and this is, perhaps, for the first time an exhaustive study which is being reported. A unique grid generation technique was developed considering the skin effect. This work is aimed at enabling modeling of the process and will in turn be useful when defining individual parameters affecting the temperature distribution in a component, subjected to induction heating. The temperature distribution in the work piece depends primarily on parameters like coil position, line speed, frequency of the current, thermal and magnetic properties of the work piece, and so on. The impact of power supply frequency and line speed were studied during the heating of the moving wire (workpiece). An in‐situ customized furnace of lower capacity was developed to carry out the validation experiments. The present modeling results are validated with online plant trial data and found to be in good agreement. Finally, the desired mechanical property achieved during trials was confirmed through tensile testing. 相似文献
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Improvement of the thermal conductivity of a phase change materials (PCM) is one effective technique to reduce phase change time in latent heat storage technology. Thermal conductivity is improved by saturating porous metals with phase change materials. The influence of effective thermal conductivity on melting time is studied by analyzing melting characteristics of a heat storage circular capsule in which porous metal saturated with PCM is inserted. Numerical and approximate analyses were made under conditions where there are uniform or non-uniform heat transfer coefficients around the cylindrical surface. Four PCMs (H2O, octadecane, Li2CO3, NaCl) and three metals (copper, aluminum and carbon steel) were selected as specific materials. Porosities of the metals were restricted to be larger than 0.9 in order to keep high capacity of latent heat storage. Results show that considerable reduction in melting time was obtained, especially for low conductivity PCMs and for high heat transfer coefficient. Melting time obtained by approximate analysis agrees well with numerical analysis. A trial estimation of optimum porosity is made balancing the desirable conditions of high latent heat capacity and reduction of melting time. Optimum porosity decreases with increase in heat transfer coefficient. 相似文献
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针对某300W大功率间歇式热源,选用9wt%膨胀石墨-56号石蜡复合材料作相变工质,铝翅片作导热结构,基于Fluent软件,采用等效比热容数学模型,在安全温度为65℃情况下,设计得到能稳定运行3500s的相变热沉。针对该相变热沉,为验证等效比热容数学模型的可靠性,搭建了相变热沉测试系统,研究了热源功率及相变工质对热沉控温性能的影响。结果表明:等效比热容数学模型有效可靠;相变材料熔点越低,相变热沉温控时间越长;而热源输入功率越高,相变工质熔点的影响将变小。此外,为降低系统内部温差、减少石蜡泄露以及降低加工成本,进一步提出了热管-回转式翅片相变热沉,热管-回转式翅片相变热沉在热源功率为300W条件下,温控时间高达4300s,内部温差仅在1.6℃以内。 相似文献