中高温工质在蒸发器中的换热模拟分析

本文采用分布参数的方法,建立了水源热泵中普遍采用的壳管式蒸发器稳态数学模型.通过中高温水源热泵试验台的实验数据同模拟计算结果的对比,验证了数学模型的准确性。应用此数学模型对中高温工质HTR01、HTR02及R134a在蒸发器典型制热运行工况,进行了模拟计算。得出了三种工质制冷剂侧换热系数沿管长的变化关系并对三种工质的换热性能进行了对比分析,为采用中高温工质的水源热泵换热器设计提供了参考依据.     

激光介质的多次吸收不均匀内热源模型

针对激光介质的内热源,以多次吸收作用为基础提出了适用于侧面双向泵浦板状激光介质的不均匀内热源模型,即多次吸收不均匀内热源模型,并与均匀内热源和一次吸收内热源模型进行了对比分析。研究表明,介质厚度及光吸收系数组成的无量纲参数不同时,三种内热源模型得到的内热源分布也有所不同。最后给出了内热源不均匀度及多次吸收模型与一次吸收模型之间的差异在不同目标值下的内热源模型适用准则。     

<Emphasis Type="Italic">Comment on</Emphasis>¶Low temperature specific heat of blue bronze K <Emphasis Type="Bold">0.30</Emphasis>MoO <Emphasis Type="Bold">3</Emphasis>, by J. Odin,J.C. Lasjaunias,K. Biljaković, K. Hasselbach,and P. Monceau

Eur. Phys. J. B 24, 315 (2001) Here we comment on a recently published paper on the presence of a phason contribution in the low temperature heat capacity data of the charge-density-wave compounds K_0.3MoO₃ and (TaSe₄)₂I. We have shown that the anomaly in the C _P / T ³ data reported by Odin et al. is straightforwardly interpreted in terms of low energy phonon modes resulting from the peculiar topology of these compounds. Received 21 February 2002 Published online 19 July 2002     

300kVA高温超导变压器电流引线漏热损耗的测量

电流引线是高温超导变压器的主要外部漏热来源,它的漏热量直接影响了超导变压器的经济性能,因此,引线的设计与漏热测量一直备受关注。文中构建了一个实验方案,运用量热法测量低压引线的漏热,并将试验结果与仿真预期值进行了对比和分析,从而验证了仿真设计的正确性。     

含有五边形—七边形缺陷的单壁纳米碳管的输运性质研究

运用第一性原理的密度泛函理论结合非平衡格林函数研究了含有五边形—七边形拓扑缺陷的纳米碳管异质结的输运性质.结果发现：拓扑缺陷对碳管的输运性质有很大影响；另外，不同类型的碳管形成的异质结的输运性质也有明显的差异. 关键词： 纳米碳管 输运性质 异质结 透射系数     

塑料闪烁体的辐照特性

利用⁶⁰Co放射源分别对3种塑料闪烁体(BC-408, EJ-200, BC-404)进行辐照损伤研究, 比较辐照前后的透射谱、发射谱及光产额的变化, 发现3种闪烁体在低剂量具有较好的抗辐照性能; 当照射剂量超过1.44×10⁴Gy时,透射谱明显变坏, 光输出减少很严重, 但发射谱却保持不变.     

傅立叶超函数和扩充傅立叶超函数与爱米特热方程

证明了傅立叶超函数和扩充傅立叶超函数可用爱米特热方程的解来表示,且用以表示的解有很良好的性质.     

多层光子晶体滤波器研究

从双层结构出发研究了一种由多块不同的单周期光子晶体组合而成的多层结构的滤波器，论述了这种滤波器的工作原理，研究表明这种结构适于制作带通、窄带通过、带阻、宽带带阻、高通以及其它各种性能的滤波器。实验和理论研究的结果相一致。     

Numerical simulation and experimental validation of heat transfer within rotating flows for three‐dimensional non‐axisymmetric,turbulent conditions

A control volume type numerical methodology for the analysis of steady three‐dimensional rotating flows with heat transfer, in both laminar and turbulent conditions, is implemented and experimentally tested. Non‐axisymmetric momentum and heat transfer phenomena are allowed for. Turbulent transport is alternatively represented through three existing versions of the k–ε model that were adjusted to take into account the turbulence anisotropy promoted by rotation, streamline curvature and thermal buoyancy. Their relative performance is evaluated by comparison of calculated local and global heat balances with those obtained through measurements in a laboratory device. A modified version of the Lam and Bremhorst, low Reynolds number model is seen to give the best results. A preliminary analysis focused on the flow structure and the transfer of heat is reported. Copyright © 2002 John Wiley & Sons, Ltd.     

The origin of the formation of cavities in galvanized coatings

The role of water‐soluble corrosion products on galvanized wires was examined. The samples used were industrial hot‐dip galvanized wires, which were exposed to the open air under all weather conditions for a relatively short time (6 and 12 months), in an urban environment close to the sea. The samples were studied by different methods, i.e. scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and optical microscopy (OM). Several phases were detected because of the galvanization procedure and the steel substrate. Furthermore, phases which were formed as a result of the reaction of zinc with the atmosphere were also detected. These were oxides like ZnO, carbonates like ZnCO₃ and hydrated Zn and Fe sulfates. Their presence influences the corrosion resistance of the wires, which finally, strongly depends on the solubility of the wires in water. The SO₄^2? compounds especially are very soluble and consequently are easily removed from the coating surface, leading to its degradation by the formation of cavities. In any case, their presence, even after a short period of exposure, implies that the coating is highly affected by the atmosphere of the modern city. Copyright © 2006 John Wiley & Sons, Ltd.