Condensation experiments for counter-current flow limitation in an inverted U-tube

In this study, we measured counter-current flow limitation (CCFL) characteristics in an inverted U-tube (18.4 mm diameter and 1.0 m straight-part length) simulating steam generator (SG) U-tubes under conditions of steam condensation at pressures of 0.1–0.14 MPa. Differential pressure ΔP between the top of the inverted U-tube and the lower tank was measured, and the flow patterns wave estimated by comparing the waveforms of ΔP with those in air–water experiments. As a result, we classified the flow patterns under CCFL conditions into CCFL-P, CCFL-L and CCFL-T. The falling water flow rate under CCFL conditions slightly increased as the pressure increased and the cooling water temperature decreased (subcooling of cooling water increased). In the case of CCFL-L, CCFL characteristics in the inverted U-tube were between those in air–water and saturated steam–water experiments at 0.1 MPa. Furthermore, we derived a Wallis type CCFL correlation and its uncertainty from CCFL data, including previously measured data, i.e., J*^1/2_G + 0.88J_L*^1/2 = 0.76 ± 0.05.     

Correlation for countercurrent flow limitation in a PWR hot leg

Numerical simulations were done to evaluate countercurrent flow limitation (CCFL) characteristics in a pressurized water reactor (PWR) hot leg with the diameter of 750 mm by using a volume of fluid (VOF) method implemented in the CFD software, FLUENT6.3.26. The calculated CCFL characteristics agreed well with known values including the UPTF data at 1.5 MPa. Sensitivity analyses for system pressures up to 8 MPa showed that the calculated CCFL characteristics in the Wallis diagram were slightly mitigated from 0.1 MPa to 1.5 MPa with increasing system pressure, but they did not change from 1.5 MPa to 8MPa. Using the CCFLs calculated in this study and values measured under air–water and steam–water conditions, a CCFL correlation and its uncertainty were derived.     

基于高压工作的多管CCFL集成驱动电源技术

为了解决CCFL驱动电源在低压工作的低效率问题,提出了一种基于高压工作的多管CCFL集成驱动电路,将CCFL驱动器(逆变器)设计在高压输入状态工作.将市电输入适配器和CCFL驱动器(逆变器)进行二合一集成一体化设计.适配器采用两级式结构,前级为PFC,后级为DC/DC变换,两路直流输出,其中的直流高压输出作为CCFL驱动器(逆变器)的输入电压;在驱动器(逆变器)中,实现了软开关;用一个集成驱动电源驱动多管CCFL,并实现多灯管的均流.实验表明,该方案提高了效率,减小了体积.     

优化 LCD 显示器的超微型荧光灯背光源的荧光粉颗粒尺寸的合成方法

用四种方法合成发红光的小颗粒 Y2O3:Eu 荧光粉,并将其加入到白光的三元化合物荧光粉中,可来制作高亮度、亚微型的 CCFLs 并运用在 LCD 显示器的背光源领域.连续的工艺流程使得大规模的制造成为可能.     

用于荧光灯管的全新第四代电乎源（一）

在荧光灯（FL）管中,人们凭借经验发现了一种全新的电子源,它是高温氩晕空间（HTACS）。HTACS在带有微小BaO颗粒钨丝线圈的受热裸金属斑点上形成,在氩气体空间中,取自处于负电势阴极电极上HTACS的电子,向处于正电势阳极电极上的HTACS运动。在点亮FL管中,来自HTACS的流光电子在所运行ac电压处于正电势期间...     

CCFL全桥谐振电子变压器原理与设计

介绍了冷阴极荧光灯(CCFL)的特点,重点阐述了基于控制器MAX8722A的CCFL全桥谐振逆变器工作原理与设计。     

TFT-LCD中高效率背光模块驱动电路

冷阴极荧光灯(CCFL)的伏安特性与齐纳二极管十分相似，可用基于Royer推挽式振荡器的逆变电路驱动CCFL．分析了CCFL的电气特性，在此基础上，进一步描述了CCFL驱动电路的工作原理，并给出了获得高效率驱动电路的器件定量计算公式以及确定各元件参数的步骤和方法。     

表面无立方相层功能梯度硬质合金的研究进展

综述了目前应用于涂层基体的无立方相层含氮功能梯度硬质合金的研究进展;详细介绍无立方相层的形成热力学基础、梯度结构特征、机理和动力学研究进展以及力学性能和切削性能;重点评述C、N含量以及组分对无立方相层的影响规律;提出获取合金系统真实的热力学相图和动力学数据是今后研究工作的重点。     

利用压电变压器设计冷阴极管驱动器的理论与方法研究

本文首先分析了压电变压器(PT)及冷阴极管(CCFL)的工作原理及特性,在此之后,针对基于PT的CCFL驱动器设计过程所牵涉的几个主要问题,即如何设计PT的驱动电路,如何选择PT的输入匹配网络,如何协调驱动器的整体效率同控制方式之间的关系,本文均给出了理论分析.除此之外,本文还建立并且分析了CCFL驱动器的等效电路模型,相关的实验结果在文章的最后给出.