CFD modeling of flow and heat transfer in a thermosyphon

In the present study a gas/liquid two-phase flow and the simultaneous evaporation and condensation phenomena in a thermosyphon was modeled. The volume of fluid (VOF) technique was used to model the interaction between these phases. Experiments in a thermosyphon were carried out at different operating conditions. The CFD predicted temperature profile in the thermosyphon was compared with experimental measurements and a good agreement was observed. It was concluded that CFD is a useful tool to model and explain the complex flow and heat transfer in a thermosyphon.     

糖厂蒸发站STD总线工控机自动控制与管理系统

国家技术项目——糖厂应用STD总线工控机对蒸发站进行多回路的生产过程自动控制和上位微机数据管理系统，已得到研制。本文在技术上全面地论述了该系统的构成及生产工艺过程实践中的合理性和可行性。这对提高糖厂的科技水平和经济效益具有深远的意义。     

凝汽器压力变化影响机组功率增量计算的研究

以汽轮机功率方程为基础,根据汽轮机变工况原理和其参数之间的变化关系,将背压变化的全过程分为亚临界工况和超临界工况,对末级进行分析计算,推导出功率增量的计算公式,确定出凝汽器真空修正曲线,有较高的精确度。     

最佳真空和最佳循环水流量传统确定方法的改进探讨

提出了对凝汽器最佳真空和最佳循环水流量计算过程的修正。即在计算凝汽器最佳真空和循环水泵的最佳组合方式时考虑了循环水的费用、汽轮机排汽阻力损失、锅炉补充水、抽气器(或真空泵)耗功率、凝结水的溶氧、凝汽器的清洁系数、极限真空、循环水最低流速这些因素。     

Synthesis of mesoporous silica in acidic condition by solvent evaporation method

Both powder-type and film-type mesoporous silica materials have been prepared by using a sol-gel process in highly acidic, solvent-rich and mild conditions by solvent evaporation method. Powder mesoporous silica which has hexagonal arrays was well synthesized within only 10 minutes, and mesoporous film was formed on the glass plate within only several seconds by supramolecular interactions between the silicate species and surfactant-templates. In particular, the synthesis time was very short compared with that of hydrothermal synthesis owing to the solvent evaporation. This method has some characteristics different from the hydrothermal method such as the following. There is no precipitation because particles do not form in the solution before solvent evaporation, bulk powder is rigid, whereas that of hydrothermal synthesis is very soft, and mesoporous materials are synthesized in acidic condition. Solvent evaporation method for the synthesis of mesoporous materials is promising because the method is very simple and time-saving.     

卧式氨冷凝器腐蚀原因及改造措施

分析了卧式氨冷器腐蚀的原因,改造后冷凝效果得到了极大的改善,设备寿命得到了延长。     

板式蒸发式冷凝器热工性能实验

对影响板式蒸发式冷凝器热工性能的主要因素——空气的湿球温度、冷凝温度、相对湿度做了实验研究。结果显示：冷凝温度和冷凝压力均随着入口空气湿球温度的升高而升高;入口空气相对湿度对压缩机功耗的影响与湿球温度对压缩机功耗的影响均比较大;对基于同一压缩系统的实验比较表明,在冷凝温度为38℃时,板式蒸发式冷凝器的热流密度比管式蒸发式冷凝器平均大30.5%;且在相同的冷凝温度下,入口空气湿球温度越低,板式蒸发式冷凝器的热流密度比管式蒸发式冷凝器大得越多。     

空冷凝汽器单元流场的耦合计算

运用计算流体力学的方法,采用多孔介质模型对电厂空冷凝汽器风机和A型框架空气侧流场进行了三维准定常耦合计算,得到了风机在不同转速时空冷单元内部的速度、温度和压力的分布.结果表明:对空冷凝汽器风机和A型框架进行耦合计算较为更合理;冷空气在凝汽器翅片间的分配不均匀,因此优化空气侧的流场分布是提高凝汽器换热效率的措施之一,为凝汽器的优化设计提供了理论依据.     

凝汽式汽轮机乏汽凝汽器传热强化的研究

在对高效换热元件横纹管的强化机理,传热与流体力学特性进行了实验研究与分析探讨的基础上,对装机容量１５００ｋＷ凝汽式汽轮机组的光滑管和横纹管凝汽器进行了工业应用的性能试验,并提出了横纹凝汽器的应用前景。     

A Study of Surface Wetting When Coating Paper

Abstract

The objective of this work will be to look at basic micro-level simulations of liquid state and movement. Defining liquid movement at fiber-coating boundaries is essential when modeling surface wetting of paper fibers. Drying studies have shown that chemical additives in base paper or coating color may reduce or increase quality, productivity, and energy efficiency considerably. The latest question is, Which are the factors that are significantly influencing liquid movement at fiber-coating boundaries? A phenomenon of less liquid drainage at lower paper moisture content is studied in this work together with the fiber hornification process. Fiber hornification is a complex change in the physicochemical properties of the fiber surface and the state of boundary molecules. Another important objective is to show how hornification may be accounted for in basic calculations. This while, printing properties of paper (mottling, etc.), may then be connected to the formation of the base paper and its drying history, explaining in more detail the importance of microlevel physicochemical property changes at fiber surfaces.