重量法测定缩合磷酸铝中三聚磷酸铝含量

基于重量法,以助溶剂TP溶解缩合磷酸铝,氯化-二氯双(乙二胺)合钴为沉淀剂,考察了样品加入量,溶解时间及沉淀反应时间对测定结果的影响。结果表明,取样1 g,溶解时间2 h,沉淀反应时间15 m in,测定结果的相对标准偏差RSD=0.39%,与热失重仪器分析法(含量测定)测定结果的相对误差为0.23%,该测定方法简捷,具有实用性。     

用于羟醛缩合反应的固体碱催化剂的制备及表征

采用溶胶凝胶法制备载体二氧化锆,并通过浸渍法负载铯制备固体碱催化剂,将其应用于以醋酸甲酯、甲醛为原料合成丙烯酸甲酯的反应。考察了不同温度,负载不同含量的硝酸铷、硝酸铯对催化剂性能的影响。利用微反色谱实验装置测试合成丙烯酸甲酯固体碱催化剂的催化活性,结果表明,负载铯比铷催化效果要好;催化剂最优条件：氧化锆负载20%铯,反应温度为380℃时,可使收率达到29.2%。     

湿空气掠过竖直平板层流强制对流凝结换热的传热传质研究(英文)

Condensation of humid air along a vertical plate was numerically investigated, with the mathematical model built on the full boundary layer equations and the film-wise condensation assumption. The velocity, heat and mass transfer characteristics at the gas-liquid interface were numerical analyzed and the results indicated that it was not reasonable to neglect the condensate film from the point of its thickness only. The condensate film thickness, interface temperature drop and the interface tangential veloc...     

用于空间聚光结构的折展机构设计与分析

针对空间太阳能电站大口径聚光结构的应用需求与运载条件相矛盾的情况,以离轴式聚光系统为研究基础,设计了一种具有折叠展开功能的次镜支撑机构。机构采用三关节串联结构为主,两组平行四杆机构为辅,可实现水平、竖直的两次展开,并能保证次镜组件在展开过程中始终保持平动状态。通过建立机构折展的运动学方程,对机构的工作空间进行了求解,规划了展开方案;对机构展开的位置、姿态精度进行了研究,分析了展开精度对机构各结构参数的敏感度;最后,在ADAMS软件中建立了折展机构的虚拟样机,对展开过程进行了仿真,验证了机构设计的正确性与合理性。     

A sub‒domain smoothed Galerkin method for solid mechanics problems

A sub?domain smoothed Galerkin method is proposed to integrate the advantages of mesh?free Galerkin method and FEM. Arbitrarily shaped sub?domains are predefined in problems domain with mesh?free nodes. In each sub?domain, based on mesh?free Galerkin weak formulation, the local discrete equation can be obtained by using the moving Kriging interpolation, which is similar to the discretization of the high?order finite elements. Strain smoothing technique is subsequently applied to the nodal integration of sub?domain by dividing the sub?domain into several smoothing cells. Moreover, condensation of DOF can also be introduced into the local discrete equations to improve the computational efficiency. The global governing equations of present method are obtained on the basis of the scheme of FEM by assembling all local discrete equations of the sub?domains. The mesh?free properties of Galerkin method are retained in each sub?domain. Several 2D elastic problems have been solved on the basis of this newly proposed method to validate its computational performance. These numerical examples proved that the newly proposed sub?domain smoothed Galerkin method is a robust technique to solve solid mechanics problems based on its characteristics of high computational efficiency, good accuracy, and convergence. Copyright © 2014 John Wiley & Sons, Ltd.     

R404A在水平强化管外的冷凝实验及数据处理方法

针对一种双侧强化换热管,实验测试和分析了制冷工质R404A在管外凝结与水在管内对流的传热规律,采用"Wilson图解法"和"Gnielinski法"两种不同的方法对实验数据进行了处理。经理论分析和实验研究表明,Wilson图解法对于双侧强化换热管管内、管外表面传热系数实验容易产生较大误差,"Gnielinski法"是更合适的方法。实验得出了管内对流传热和管外凝结传热的计算关联式及传热的强化倍率。对于制冷剂R404A,在强化管外凝结的表面传热系数随着壁面过冷度的增加而增大,呈现出与纯工质光滑管外冷凝时不同的变化趋势。     

Sweep‐out flow of film condensation on vertical plates with horizontal grooves

We have investigated fluid flow characteristics of film‐wise condensation on vertical plates with horizontal periodic grooves. Condensate stays at the edge of the grooves due to the surface tension. The condensate starts to flow, however, when the balance between the surface tension and the condensate's own weight is broken. It is found that the condensate flows downward successively and periodically from the top part of the plate as a group. In addition, we have obtained the relation between the frequencies of the periodic flow and the degree of sub‐cooling for two different pitches of the grooves. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20249     

Recent trends in the chemistry of 2-aminobenzothiazoles

The chemistry of 2-aminobenzothiazoles has gained increased interest in both synthetic organic chemistry and biological fields, since a large number of developments in the use of such compounds, covering the literature up to 2007, seem to be of considerable value. The present review presents their synthetic methods and chemical reactions. The reactions are subdivided in groups that cover reactions at the amino substituent without touching the benzene ring and reactions which involve both nitrogen in the formal amidine system to give fused heterocyclic systems. Most imaginable reaction types have been successfully applied and used, as many of the synthesized compounds exhibit interesting biological activity in various fields.     

3,4-Dimethyl-2,5-functionalized thieno[2,3-b]thiophenes: versatile precursors for novel bis-thiazoles

Synthesis of novel bis(thiazoles) 19–22, 24, 25, 30 and 31 is reported. Thus, reaction of the bis(α-bromoketones) 14 and 15 with the corresponding thioamide derivatives 16–18 in refluxing EtOH in the presence of triethylamine afforded 19–22 in good yields. On the other hand, the novel bis(thiazoles) 24 and 25 can be synthesized by the reaction of 14 and 15 with the corresponding p-chlorobenzaldehyde thiosemicarbazones 23 in refluxing EtOH. The novel isomeric bis(thiazoles) 30 and 31 can also be synthesized by a reaction of the corresponding bis(benzaldehyde thiosemicarbazones) 27 and 28 with p-chlorophenacyl bromide 29. Compounds 27 and 28 were obtained by condensation of the corresponding bis(aldehydes) 12 and 13 with thiosemicarbazide 26.     

Bubble columns for condensation at high concentrations of noncondensable gas: Heat‐transfer model and experiments

Carrier gas based thermodynamic cycles are common in water desalination applications. These cycles often require condensation of water vapor out of the carrier gas stream. As the carrier gas is most likely a noncondensable gas present in very high concentrations (60–95%), a large additional resistance to heat transfer is present. It is proposed to reduce the aforementioned thermal resistance by condensing the vapor–gas mixture in a column of cold liquid rather than on a cold surface using a bubble column heat exchanger. A theoretical predictive model for estimating the heat‐transfer rates and new experimental data to validate this model are described. The model is purely physics based without the need for any adjustable parameters, and it is shown to predict heat rates within 0 to ?20% of the experimental values. The experiments demonstrate that heat‐transfer rates in the proposed device are up to an order magnitude higher than those achieved in existing state‐of‐the‐art dehumidifiers. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1780–1790, 2013