Vapor-liquid equilibrium and volumetric properties calculations for solutions in the supercritical carbon dioxide

The calculations of gas solubilities in supercritical solvents require equations of state remaining accurate in the critical range, which are difficult to obtain with classical models. In this work, the Helmholtz energy of a mixture is considered as the sum of the Helmholtz energies of pure components taken at a constant packing fraction and of a residual term which may have the form of a RedlichKister, Van Laar, NRTL, UNIQUAC, or UNIFAC function. Thus it is possible to assign to a given component an equation of state whose form is different from that of the others. This model has been applied to binary systems containing supercritical carbon dioxide. The results are improved with respect to those obtained with the classical model for vapor-liquid equilibria and for volumetric properties.     

龙开口水电站溢流坝段动力模型破坏试验研究

采用仿真混凝土材料研究了龙开口水电站溢流坝段在不同因素影响下的动力破坏特征,并通过对6个模型试验结果的分析探讨了溢流坝段的动力破坏机理。试验中考虑了坝体-库水的动力相互作用以及横河向地震动对大坝破坏的影响,采用规范谱波和场地谱波两种地震动激励进行模型超载破坏分析。试验结果为工程设计和评价溢流坝段的抗震性能提供依据。     

中山包水电站钢岔管设计

中山包水电站钢岔管在天生桥二级水电站 6号压力钢管下平段分岔 ,岔管HD值达 15 40m2 ,结构体形复杂 ,采用NK HITEN780A Z35和NK HITEN6 90B高强度钢材制造安装 ,在国内水电工程中实际应用较少。文章着重介绍岔管的布置、结构分析和焊缝的无损检验要求。中山包水电站的正常发电运行 ,为 80kg/mm2 级高强钢在国内水电行业的应用提供了第 3个成功实例     

Large-scale cooling towers as part of an efficient and cleaner energy generating technology

The present paper will outline the main aspects of the design and construction of cooling towers in Germany in the last decade. As part of electricity generating power plants, cooling towers play a significant role for the availability of reliable energy supplies, in a manner compatible with environmental requirements. They definitely belong to the largest and thinnest concrete structures at present. Because of the combined action of wind, thermal and moisture effects, special care has to be taken with regard to fatigue, cracking and corrosion to ensure an adequate level of safety and durability. Such a design strategy has been employed for the world’s tallest cooling tower at the Niederaussem power plant in Germany, with an overall height of 200 m and thickness values of 22–24 cm. Special considerations included the realistic non-axisymmetric distribution of soil characteristics, wind action due to interference effects (as determined by wind-tunnel tests), optimisation of the shell shape to improve structural and dynamic behaviour, injection of the cleaned flue-gas into the cooling tower, and the use of high-performance concrete (85 MPa) to improve shell resistance against acid attack by the cleaned flue-gas. The paper will present some results of an actual research project on this problem, which was conducted at the University of Wuppertal, to explore the use of high-performance concrete on design, stability and durability of cooling tower shells.     

氧浓度对近临界水中纤维素分解的影响

研究了不同初始氧浓度对纤维素在近临界水中分解的影响，实验结果表明，氧浓度显著地影响产物总碳收支平衡，液相不同组分的收率、气体的产量以及气相产物的组成，微量氧对产物总碳收支平衡影响不大，而对液相不同组分的收率有一定的影响。从实验结果可以看出，离子型反应机理在纤维素水解的第一步中起主导作用。而单糖的进一步分解是一个以自由基反应机理为主的过程。     

环境因素对碳钢点蚀临界电势的影响

采用动电势扫描法测定了不同体系中碳钢发生点蚀的临界电势Eb。结果表明 :当Cl- 浓度 <0 .0 1mol/L时 ,随Cl- 浓度增加 ,临界电势负移并与Cl- 浓度成线性关系 ;pH值在 7～ 11之间 ,随pH值增加 ,临界电势正移并与pH值成线性关系 ;随温度增加 ,临界电势负移并与温度成线性关系。     

水性聚氨酯电导率与聚沉值的研究

研究了软（硬）段含羧基的水性阴离子纳米聚氨酯体系的n(NCO)/n(OH)比值，COOH的质量分类，反离子各类，合成方法与电导率关系及产生的原因；探讨了该体系的n(NCO)/n(OH)值，COOH的质量分数，合成方法与临界聚沉值（Cc.c)的关系和规律。并分析，比较了软（硬）段含羧基的水性阴离子聚氨酯体系电导率与Cc.c二者关系，得出了随COOH的质量分数升高，二者变化相同，随n(NCO)/n(OH)比值升高,二者变化相反的结论。     

正交异性矩形薄板的稳定性分析

本文求得了正交异性矩形薄板屈曲位移函数微分方程的一般解。可用以求解任意边界矩形板的稳定问题。以两邻边简支，另两边自由的正方形板为例进行了计算。     

Magnetic field hysteresis of critical currents in Bi(2223)/Ag tapes and a way to overcome it

Experiments showing hysteresis of critical currents versus the external magnetic field I_c(B_e) were performed with two multifilamentary Bi(2223)/Ag tapes. The I_c(B_e) hysteresis is observable in the transversal as well as in the longitudinal orientation of the long axis of the tape with respect to the magnetic field. Based on the idea that the hysteresis is the effect of trapped flux in a network of well-connected current paths, a way to overcome this effect has been proposed and experimentally verified. The induced frozen-in screening currents are split into several parallel current patterns by cycling the external magnetic field around the adjusted value. Using the proposed method, the ‘neutral’ I_c(B_e) characteristics have been found. Approximate calculations of the penetration depth of the trapped flux show that the network of well-connected current paths could be formed by several disk-shaped grains (≈ Φ8 × 0.4 μ) stacked into more or less axially ordered (quasi cylindrical) colonies of average dimensions estimated to ≈ Φ8 × 4 μm.     

BCC金属Nb的重离子辐射损伤研究

采用81 MeV碳离子辐照,模拟中子注量为10~(23)/cm~2的堆中子在Nb中产生的辐射损伤,用时间微分扰动角关联和正电子湮没二种方法研究辐射损伤及其高温退火效应。实验发现经注量2.5×10~(16)/cm~2的碳离子辐照后,在BCC金属Nb中产生单空位和双空位二种缺陷。随退火温度升高,双空位分解,单空位的总浓度逐步减小,经过1058K退火后,在Nb中由辐射损伤造成的缺陷消失。