壳管式污水换热器的设计对堵塞换热的影响

壳管式换热器在污水源热泵系统中间接提取污水热源,用这种换热器作为城市污水与清水之间的换热器,间接降低污水对机组的腐蚀损害.本文采用壳管式换热器作为污水与水间的换热器,首先对其进行结构设计计算,然后根据设计参数分析污水流速对堵塞换热的影响规律.     

波壁管式换热器内壳侧流体流动与换热特性

传统的直壁管式换热器的换热效率不高,为了增强换热器内流体的换热效率。采用数值模拟的方法对<1-2>型波壁管式换热器内流体的流动与换热特性进行了研究,重点探讨了雷诺数Re与波壁管半径比i对换热器内流体的流动特性、阻力特性、换热特性以及综合换热性能的影响。结果发现,与直壁管式换热器相比,波壁管式换热器内流体的流动状态能够得到较大的改善。波壁管式换热器壳程流体的进出口平均压降比直壁管式换热器低,平均压降最大可降低11.01%,并且发现随着Re的增加,平均压降明显增大,随着i的增加,平均压降略有增大。波壁管式换热器壳程内流体的对流换热系数h_s明显大于直壁管式换热器,h_s最大可增加14.17%。h_s随着Re的增大逐渐增加,而i对h_s的影响不明显。同时发现波壁管式换热器的综合换热性能与雷诺数Re成正相关,而与半径比i成负相关。与直壁管式换热器相比,波壁管式换热器的综合换热性能更强。     

机械密封混合摩擦微极流体弹性润滑的数值模拟

将弹性微极流体润滑理论应用于机械密封混合摩擦的研究,建立力学模型.考虑流体的可压缩性,构建混合摩擦的数学模型,利用有限差分法进行数值求解,获得机械密封性能参数值,为优化设计奠定理论基础.     

摩托车发动机缸套内表面激光微造型的润滑工艺

基于流体动压润滑理论,建立了摩托车发动机缸套表面有规则抛物面微凹腔结构的流体动压润滑数学模型;结合雷诺空化边界条件、利用超松弛迭代法、采用Matlab编程求解离散后的数学模型;分析了各种工艺参数对流体动压润滑性能的影响规律,得到了最优的理论工艺参数组合.     

新型金属氢化物反应床传热性能分析

运用计算流体动力学（CFD）方法,对弓形折流板壳管式金属氢化物反应床进行了数值模拟.预测了反应床壳侧的流体流动状态,分析了在不同折流板数量下,反应床中壳侧的流动状态、壳侧压降和换热管内合金的温度分布.分析计算结果发现,当壳侧折流板数较多时,热流介质的流动均匀性较好,其流动死区较少,换热性能较好,壳侧压降也较大,压降损失主要存在于折流板圆缺处;增加折流板高度会有效地减少壳侧压降,并对换热性能影响很少.针对弓形折流板壳管式反应床传热性能较差,引入螺旋式折流板对反应床进行优化.结果表明,该反应床流体流动状态为旋转式,其壳侧流体的均匀性、壳侧压降以及换热管的温度分布均匀性均明显优于弓形折流板.
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Abstract：     

FEM-BEM耦合方法分析弹性目标的声散射问题

利用有限元耦合边界元方法,建立了无界流体中内部有填充物的弹性壳体的声散射问题计算的数学模型,其中包括内部填充物与壳体的耦合、壳体与外部流体的耦合.为验证数学模型的正确性,对水中中空及有填充物的弹性球壳的反向散射特性进行了数值计算.结果表明,在低频时,散射声场的数值计算结果与解析解较吻合.进一步使用该方法计算了一端带半球帽的圆柱壳在中空和有填充物时的反向散射特性,得出了填充物可起到变异作用.     

高温熔融盐壳管式相变换热器的传热特性

建立了高温熔融盐壳管式相变换热器的同心套管模型.采用Fluent软件,分析了在考虑相变区域自然对流条件下,熔融盐流体与相变材料的物性参数、内管进口温度与进口流向等因素对液相率与熔化时间的影响,并在熔融盐传热-蓄热实验平台上进行了试验研究.发现:考虑相变区域自然对流时,总的熔化时间减少16.2%;模拟得到的壳侧相变材料温...     

水下有限长圆柱壳受冲击波作用的瞬态动力响应

对有限长圆柱壳在水下受冲击波(声学场)作用时的瞬态动力响应问题进行了研究，用有限元法来模拟结构，边界元法来模拟无限域流体，通过结构与流体的接触面上的力和位移的连续条件形成耦合求解方法，并在时域里进行求解.给出了典型算例，并对结果进行了讨论，得出了有关结论.     

高温高压模拟井筒流固耦合传热建模与数值求解

模拟井筒加温系统是用于模拟井下高温高压环境,对射孔器材进行高温性能检测的一种实验装置。模拟井筒为耐高温高压的厚壁圆柱形封闭腔体,为研究加温过程中腔体内流体与厚壁腔体之间的动态耦合传热过程,根据模拟井筒加热物理模型,建立了模拟井筒耦合传热数学模型。应用有限差分法离散模拟井筒耦合传热数学模型,得出厚壁井筒和腔体内流体数学模型的离散格式。使用迭代法分别计算厚壁井筒与腔体内流体区域的传热过程,在厚壁井筒与流体的交界边界处应用热平衡法进行耦合传热计算,求解模拟井筒耦合传热温度场,腔体内流体区域采用投影法对数学模型进行求解。通过仿真计算与实验结果的对比,验证了建立的高温高压模拟井筒流固耦合传热模型的正确性。     

化工大系统的分解及反应器的稳定性理论(综述)

本文介绍了连续搅拌槽反应器(CSTR)、n个CSTR、聚合反应器、管式反应器、具有反应与扩散的开系统反应器等数学模型的建立;静态(奇点)(包括二组分多分子静态的多重性、唯一性)的求解;依李雅普诺夫直接法而论化工反应器系统中稳定性的判定及化工复合系统如具有反应与扩散的开系统,n个CSTR串连及用16个CSTR串连来近似模拟轴向扩散绝热的管式反应器等在稳定性理论中的分解问题的近代发展.     

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.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

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