R123在GY新型强化管外池沸腾的传热实验

为强化低温热能发电有机朗肯循环系统的传热过程,采用机械加工方法研发肋管表面似龙鳞状的新型三维外肋强化传热管即GY管。对工质R123在光管、GY管水平单管外池沸腾换热进行实验研究,在常压条件下(正常沸点为27.4℃)得到热流密度与沸腾换热系数、管内雷诺数与传热系数的关系模型。将光管管外沸腾换热系数的实验值和Cooper公式计算值进行比较可知其变化趋势一致,实验值与Cooper公式计算值的偏差小于12%;同时,得到GY管传热系数随管内雷诺数的变化规律。实验结果表明:当雷诺数在(4.9~11.5)×103范围内时,与光管比较,GY管的传热系数强化倍率为3.10~3.45。因此,GY管是一种具有优良管外沸腾换热性能的强化管,能有效强化有机工质的换热过程。     

带肋板尾缘开缝叶片内的流动传热性能研究

针对燃气透平带肋板的尾缘开缝叶片,采用RANS(Reynolds Averaged Navier-Stokes)方程求解结合SST γ-Re_θ转换模型数值方法,研究了3种来流湍流度、3种来流雷诺数和3种冷气质量流量比条件下叶片和尾缘开缝区域的流动传热性能,并与无肋板开缝叶片进行了对比,利用实验数据考核了数值方法的有效性。计算结果表明:随着来流湍流度的增大,带肋板的尾缘开缝叶片表面传热系数逐渐增大,开缝壁面的传热系数基本不变,能量损失系数和总压损失系数随之增加;在相同来流湍流度时,增加来流雷诺数可降低损失;增大冷气质量流量比对叶片表面的传热系数影响很小,但可显著提升开缝壁面的传热系数;与无肋板的开缝叶片相比,带肋板的尾缘开缝叶片表面的传热系数和压力系数更低,开缝壁面换热系数更高;当Re为2.0×10⁶时,带肋板的开缝壁面平均换热系数比无肋板时的高14.46%,来流雷诺数分别为0.5×10⁶、1.0×10⁶、2.0×10⁶时,相比无肋板开缝叶片,带肋板尾缘开缝叶片的能量损失系数分别...     

高通量换热器研制及在大型石化装置中的节能应用

开发了烧结型表面多孔高通量换热管及其换热器.以乙醇为介质评价了表面多孔换热管的沸腾传热性能.研究表明,表面多孔换热管强化传热效果显著,在酒精中的传热效果是光管的8.7～12.1倍.以1.8 g/L CaSO4盐溶液为介质经240 h阻垢性能试验,结果表明表面多孔换热管具有良好的抗垢性能,在溶盐中多孔管沸腾传热系数始终大于光管的沸腾传热系数.工业化应用考核表明,采用该烧结型表面多孔换热管设计制造的高通量换热器,不仅可以大幅度提高相关流程装置的产能,而且可以明显降低能耗.     

带次流道的波状细通道热沉熵产分析

【目的】探究次流道对细通道热沉换热性能的影响。【方法】使用CFD软件对常规直细通道热沉(CMS)、波状细通道热沉(WMS)、带次流道的波状细通道热沉(WMS-S)3种细通道热沉进行数值模拟和对比分析。【结果】WMS和WMS-S的传热系数k比CMS显著增加,低Re数时,WMS-S比WMS的传热性能略有增加,且WMS-S的传热不可逆损失较小。【结论】在低Re数时,次流道能有效增强波状细通道热沉传热系数k,且能够减小传热不可逆造成的能量损失。     

板棒式换热器传热性能分析(Ⅱ)

以单位质量材耗的换热能力最大为目标函数,分析研究了不同雷诺数Re的操作条件下肋棒长度、直径及板厚之间的关系.结果表明当雷诺数较小时肋棒才可有效地起到强化传热的作用,且随着肋棒直径的减小强化传热作用增强;当板厚为3mm、雷诺数在10     

螺旋丝径对内插螺旋线圈圆管内油类介质强迫对流的影响

实验研究了内插螺旋线圈的水平圆管内30~#透平油的对流强化传热及流阻特性,探索了螺旋丝径的影响。实验圆管为φ10×0.5×900mm的紫铜圆管。其它参数范围为:193.97≤Pr≤464.36;2.7×10~2≤Re≤2.5×10~3;0.333≤t/D≤1.333和3.75≤t/d≤24.实验表明,Re及丝径的增大均使换热系数及阻力增大;Re的增大亦同时造成h/h_及△P/△P_两个比值的增加。Pr的减小可使换热增强,流阻减小,采用(Nu/Nu_)/(f/f_)~(0.29)作为评估传热及流阻综合性能的判据,实验范围内该判据之值介于2.09～3.23之间。此外,综合实验数据得到了传热及流阻两个关系式。     

大量不凝性气体存在时不同润湿性管束对流冷凝传热实验研究

为了实现工业中大量不凝性气体存在场合下蒸气的高效冷凝传热,建立了混合蒸气水平管束外对流冷凝传热实验系统,通过化学刻蚀与自组装方法对光管管束、2D肋管管束和3D肋管管束进行疏水与超疏水表面改性处理。当大量不凝性气体存在时,对不同润湿性管束表面的冷凝形式及管束间冷凝液流型进行可视化观测。实验研究了冷却水流速、混合蒸气流速、水蒸气体积分数等因素对不同润湿性的冷凝式换热器对流冷凝传热系数的影响,并分析不同水蒸气体积分数条件下管束效应的影响。通过实验研究发现,当大量不凝性气体存在时,冷凝液在管束间形成滴状流,水蒸气体积分数对不同润湿性的冷凝式换热器的对流冷凝传热特性影响显著,随着管排数增加,对流冷凝传热系数增大,管束效应对超疏水光管管束的强化作用最大,当水蒸气的体积分数约为11%时,9排超疏水光管管束的对流冷凝传热系数是单排的1.53倍,而当水蒸气体积分数约为23%时,9排超疏水光管管束的对流冷凝传热系数是单排的1.34倍。     

航空发动机涡轮叶片尾缘楔形通道交错肋冷却实验

为研究涡轮叶片尾缘部分楔形通道交错肋流动传热性能,对其进行实验研究.实验应用瞬态液晶测试技术,对比研究了交错肋上、下主表面的局部传热特性,同时用压力扫描阀测得不同雷诺数下的通道压力损失.研究结果表明：尾缘段转折流动配置下,楔形通道交错肋上、下主表面传热差异显著,下主表面平均努塞尔数比上主表面平均高30%以上,尾缘楔形通道内交错肋结构主表面平均换热系数高出针肋结构约46%;交错肋上、下通道之间的交界面处存在强烈的质量交换作用,上、下主表面间断性的高换热区与上、下通道交界面呈现对应关系;随入口雷诺数的增加,通道压降快速增大.楔形通道交错肋压降是针肋的5～7倍,但其换热面积高出针肋107.4%,仍比针肋冷却增加约66%的综合换热性能.     

涡节型、酒窝型强化管管内沸腾传热特性实验

以微型Capstone C30燃气轮机排放的烟气余热为热源,研究涡节结构强化管、酒窝结构强化管和光管管内沸腾换热特性。实验结果表明：涡节型结构强化传热管管内沸腾换热系数约为光管的1.6~2.1倍,管外对流传热系数约为光管的1.3~1.5倍,总传热系数约为光管的1.4~1.5倍;酒窝型强化传热管管内沸腾换热系数约为光管的2.1~2.5倍,管外对流传热系数约为光管的1.8~2.0倍,总传热系数约为光管的1.9~2.1倍。分析了涡节型强化传热管和酒窝型强化传热管较光管传热性能好的原因。     

表面活性剂减阻溶液与室内空气环境的换热性能研究

对供暖系统中管道内流动的表面活性剂减阻溶液与室内自然对流的空气环境换热过程进行了理论分析和实例计算.结果表明,管壁外侧对空气的传热过程是串联传热过程的控制步骤,传热过程性能要用总传热系数大小来评价,与应用表面活性剂减阻导致溶液传热系数下降关系不大.     

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