Numerical investigation of boiling flow of nitrogen in a vertical tube using the two-fluid model

The two-fluid model has been extensively used in modeling boiling flow of water, however, there are few equivalent studies of boiling flow of cryogenic liquids. In the present study, the two-fluid model which is basically included in the CFX code was modified by incorporating new closure correlations, then boiling flow of liquid nitrogen in a vertical tube was numerically simulated using the basic model and the modified model, respectively. Comparison with experimental data shows that the modified model is satisfactorily improved in accuracy. This study demonstrated that the following parameters and models are important for accurate prediction: the lift force, the bubble diameter distribution and the active site density, among which, the active site density has the most significant effect.     

Synthesis and characterization of sulfonated poly(arylene ether ketone ketone sulfone) membranes for application in proton exchange membrane fuel cells

A series of sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS) copolymers were synthesized by nucleophilic polycondensation. The copolymers exhibit good thermal and oxidative stabilities, all the SPAEKKS copolymers can be cast into tough membranes. Ionic exchange capacities (IEC), water uptake properties, thermal stabilities, methanol diffusion coefficients and proton conductivities were thoroughly studied. Also the microstructures of the membranes were investigated by TEM. The proton conductivity of the SPAEKKS-4 membrane is close to that of Nafion-117 at 80 °C. The methanol diffusion coefficient of the membrane is much lower than that of Nafion-117 under the same testing conditions. The SPAEKKS membranes are promising in proton exchange membranes fuel cell (PEMFC) application.     

分宜100 MW循环流化床锅炉旋风分离器分离效率的计算

为了得到分宜发电有限责任公司100MW循环流化床（CFB）锅炉旋风分离器的分离效率，对CFB锅炉分离器分离效率的工程计算方法进行了研究。在热态试验条件下通过直接测量物料浓度进行分离器分离效率的计算是很困难的，同时该方法还需要辅以分离器进出口物料粒径分布的测量，在数据处理和数据精度上都存在问题。为此从工程应用的角度出发，通过炉膛压力计算分离器人口烟气携带的物料浓度，采用物料平衡计算飞灰浓度，从而提出了一种工程上简单准确并且实时的计算测量方法。利用该方法，得到了分宜100MW CFB锅炉旋风分离器的分离效率在99．17％左右，同时得到循环倍率为24．7。     

火电厂NOX污染排放控制方法探讨

NOx的排放控制将是火电厂未来环境保护的重要任务，减少NOx排放的一些方法。     

阀体强度计算比较与分析

以我厂设计的DN300；PN25闸阀的铸造阀体为例，应用我厂、美国、原西德等国有关强度计算标准进行对比性计算，加以分析，证明了尽管计算方法有一定的差别，但结果基本一致。     

不锈钢管子管板自动钨极氩弧焊的试验研究

本文介绍了不锈钢管子管板焊的工艺试验情况,包括试验的内容和为保证焊接质量所采用的工艺参数和操作要点.     

循环流化床带外置换热器系统的热循环回路

某公司引进Alstom循环流化床锅炉技术中的，带外置换热器系统的热循环回路。     

燃用印尼煤时直吹式制粉系统安全运行探讨

针对广州恒运电厂燃用高挥发分的印尼煤时直吹式制粉系统的安全运行问题,分析了煤粉在磨煤机内爆炸的原因及其影响因素,并提出了防止直吹式制粉系统爆炸的具体措施,防止了燃用印尼煤时制粉系统爆炸的发生,提高了制粉系统运行的安全性。     

提高喷油泵齿杆滑动性的工艺改进

随着柴油机的发展,齿轮齿杆式喷油泵的油量调节机构得到了越来越广泛的应用。本文通过工艺改进解决了齿杆滑动性差的问题,使批量生产的喷油泵总成齿杆的滑动性大大提高。     

锥孔孔深检具设计

在分析了用传统方法测量L480B-2提前器用联接盘1：5锥孔量规尺寸φ15至端面深度尺寸10-0^0.036所存在的弊端的同时,介绍了新设计检具的结构原理和定量测量装置配置。现场使用证明：新检具便捷、高效、可靠,一改过去的定性测量为定量测量,实现了对尺寸参数的精确测量和在生产现场对工件进行100％的检测,保证了产品的质量,满足了生产需要。