高温套管式熔融盐相变蓄热器蓄热性能实验研究

为揭示高温熔融盐相变蓄热器的蓄放热特性,并进一步提高其蓄热性能,搭建了高温梯级熔融盐相变蓄热实验台(最高蓄热温度可达800℃),对高温套管式熔融盐相变蓄热器开展了蓄/放热性能实验研究。首先选择蓄热性能优良的二元碳酸盐作为高温相变蓄热材料,测试了其热物性;其次实验研究了高温套管式熔融盐相变蓄热器的总蓄/放热时间、平均蓄/放热速率以及蓄热效率等蓄/放热性能。结果显示:相变蓄热材料的熔化过程存在着非均匀性;在放热过程中,位于不同位置的相变蓄热材料存在着不同程度的过冷现象。最后,实验研究了在熔融盐侧添加环形肋片对高温熔融盐相变蓄热器的蓄/放热性能的强化效果,以及空气温度、质量流量等运行参数分别对光管和肋片管相变蓄热器总蓄/放热量、平均蓄/放热速率以及蓄热效率的影响。结果显示,在添加肋片后,相变蓄热材料温度分布更加均匀,蓄热过程结束时相变蓄热材料的最大温差由51.1℃下降到43.2℃,下降了15.4%,高温相变蓄热器的平均蓄热速率与平均放热速率分别增加了6.8%和9.1%。实验结果可为后续高温梯级熔融盐相变蓄热器的性能研究以及实际应用提供参考。     

相变蓄热器多温位释热特性模拟研究

针对翅片管式相变蓄热器多温位释热过程进行数值模拟,分析其多温位相变传热过程的放热特性。结果表明,蓄热器低温级相变材料温度的变化速率高于高温级相变材料温度的变化速率,这是因为蓄热器低温级制冷剂流量高于高温级制冷剂流量,且低温级制冷剂出口温度与相变材料的温差高于高温级。采用热焓法对单管蓄热器模型在第一类边界条件下的融化和凝固过程进行数值模拟,并与实验测得的数据进行对比,模拟分析蓄热器高、低温级液相率及温度变化情况,综合分析相变传热过程的蓄放热特性,为进一步优化蓄能除霜过程高、低温级能量分配提供理论基础。     

蒸汽蓄热器放热过程中蒸汽带水规律的试验研究

本文通过对蒸汽蓄热器放热过程的分析,运用相似理论,从描述蒸汽带水过程的数学方程中整理出蒸汽湿度准则关系式,并以水为工质,在蓄热器放热试验台上进行了试验,将试验数据代入准则关系式,回归计算得到了蒸汽湿度计算公式。在实际蒸汽蓄热器的工业性试验中,用该公式计算得到的湿度和实测湿度基本相符。     

微重力条件下列管相变蓄热器的传热特性研究及拓扑优化

基于相变蓄热器在航天航空领域的应用，对列管式蓄热器建立物理模型和数学模型，采用数值模拟研究其在不同重力及雷诺数下的传热特性，此外引入基于变密度法的拓扑优化方法对蓄热器进行结构优化，设计出一种不等长拓扑肋片模型，并对比研究各因素对相变材料熔化速度的影响。研究结果表明，相同雷诺数时微重力条件下相变材料的熔化速度相比于有重力条件下的较慢，不同雷诺数时微重力条件下的熔化速度比有重力条件下的熔化速度分别减小了82.7%,86.1%,90.1%。但在微重力条件下，增大雷诺数已不足以有效提升相变材料的熔化速度。与无肋片管相比，经拓扑优化所得肋片模型的强化换热效果明显，在微重力条件下其相变材料熔化时间相比于无肋片管熔化时间缩短了47.83%，表明所设计的拓扑优化肋片模型可有效地减小微重力对蓄/放热速率的影响。     

空燃比和涡流比对汽油机放热率和火焰传播速度的影响

实验研究了空燃比和涡流比对汽油机油耗率、循环波动率、放热率和表观火焰传播速度的影响,介绍了根据实测放热规律计算火焰传播速度的方法。实验和计算表明,空燃比增加,放热率和火焰速度减慢;而一个适中的涡流比即能得到较快的放热率和火焰速度。     

压力管道受弹体侧向冲击破坏的实验研究及仿真分析

对充液充压薄壁圆管侧向受平头及半球头弹体冲击问题进行了实验研究及计算机模拟，获得了薄壁圆管变形及破坏模态，实验观察到临界破坏速度随内充介质压力的增加而减小，而计算机的动画给出了圆管变形及破坏的发展过程。计算结果与实验测量结果相比较，其一致性是令人满意的。     

蒸汽蓄热器降压自蒸发试验研究

蒸汽蓄热器作为一种有效的节能装置在工业中的应用正日趋广泛。在蒸汽蓄热器设计中,对于其放热过程中蒸汽带水的问题,以往人们都是沿用锅炉汽包的内部规律来进行分析的。本文通过对这两种热力设备工作特点的比较,认为它们的工作过程有着很大的差别,并指出这种“沿用”是欠妥的。文中描述了在可视系统中观察到的降压自蒸发现象,结合在测试系统上测得的放热特性曲线,从理论上对蒸汽蓄热器降压自蒸发过程进行了分析。阐明了影响低压自蒸发过程的各种因素,并且归纳出蒸汽蓄热器降压自蒸发的几种类型:纯表面蒸发型、表面蒸发——间歇沸腾蒸发型及表面蒸发——连续沸腾蒸发型。     

潜热储能凝固过程焓模型与相似模型特性分析

本文讨论了用焓模型及相似模型在相同参数下圆翅片管蓄热器在凝固过程中的放热特性,不同的Bi数及Ste数对上述两种数学模型计算结果所产生的影响及其原因。从而判定两模型的应用范围及前景,为设计潜热储能设备提供依据。文中列出了有关的放热特性曲线及实验所得的数据,示出了固液界面在凝固过程中的形状及其移动规律。     

蒸汽蓄热器充汽装置最佳结构参数的实验研究

在与工业实际应用相似的蒸汽蓄热器上,研究了循环筒、喷嘴的结构参数及其对充汽过程的影响,并得到了试验条件下充热装置的最佳结构尺寸。     

太阳能热发电复合相变蓄热材料的实验研究

针对相变材料无机盐KNO3/NaNO3(摩尔比50/50)导热系数低,影响了蓄热系统充放热过程传热效率,制备了适用于太阳能热发电系统的无机盐/膨胀石墨复合相变材料,对复合相变材料的微观结构和热物性进行了分析,并搭建充放热测试平台对相变材料分别进行了热性能研究。结果表明:复合相变材料中的无机盐均匀分布在膨胀石墨中,其相变潜热与基于复合材料中无机盐质量分数的计算值相当,添加膨胀石墨后相变材料的导热系数得到了改善;在充热过程中纯无机盐的换热方式以自然对流为主,同一蓄热单元内沿轴向上下位置温差较大,不同蓄热单元内相同位置完成充热过程所需时间从上到下依次增加,而对于无机盐/膨胀石墨复合相变材料(质量比90/10)充热过程以导热为主;与纯无机盐不同,同一蓄热单元内沿轴向上下位置温度变化趋势基本一致,不同蓄热单元相同位置完成充热过程所需时间几乎没有差别。添加膨胀石墨后,相变材料的充热过程所需时间减少较小,而放热过程所需时间减少约45%,传热介质流量的变化对复合相变材料充/放热过程影响较小。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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