Experimental study on prediction model of wet gas pressure drop across single-orifice plate in horizontal pipes in the low gas phase Froude number region

The pressure drop prediction of wet gas across single-orifice plate in horizontal pipes had been solved satisfactorily under an annular-mist flow in the upstream of orifice plates. However, this pressure drop prediction is still not clearly determined when the upstream is in an intermittent flow or stratified flow, which is corresponding to a region of low Fr_G (gas phase Froude number) in the flow pattern map of wet gases. In this study, the wet gas pressure drop across a single-orifice plate was experimentally investigated in the low Fr_G region. By the experiment, the flow pattern transition in the downstream of single-orifice plates, as well as the effects of Fr_G and Fr_L (liquid phase Froude number) on Φ_G (gas phase multiplier), were determined and compared when the upstream is in the flow pattern transition and the stratified flow region, respectively. Prediction performances were examined on the available pressure drop models. It was found that no model could be capable of jointly predicting the wet gas pressure drop in the low Fr_G region with an acceptable accuracy. With a new method of correlating Fr_G and Fr_L simultaneously, new correlations were proposed for the low Fr_G region. Among which the modified Chisholm model shows the best prediction accuracies, with the prediction deviations of Φ_G being within 7% and 3% when the upstream is in flow pattern transition and stratified flow region, respectively.     

Rational design on photoelectrodes and devices to boost photoelectrochemical performance of solar-driven water splitting: a mini review

As an eco-friendly, efficient, and low-cost technique, photoelectrochemical water splitting has attracted growing interest in the production of clean and sustainable hydrogen by the conversion of abundant solar energy. In the photoelectrochemical system, the photoelectrode plays a vital role in absorbing the energy of sunlight to trigger the water splitting process and the overall efficiency depends largely on the integration and design of photoelectrochemical devices. In recent years, the optimization of photoelectrodes and photoelectrochemical devices to achieve highly efficient hydrogen production has been extensively investigated. In this paper, a concise review of recent advances in the modification of nanostructured photoelectrodes and the design of photoelectrochemical devices is presented. Meanwhile, the general principles of structural and morphological factors in altering the photoelectrochemical performance of photoelectrodes are discussed. Furthermore, the performance indicators and first principles to describe the behaviors of charge carriers are analyzed, which will be of profound guiding significance to increasing the overall efficiency of the photoelectrochemical water splitting system. Finally, current challenges and prospects for an in-depth understanding of reaction mechanisms using advanced characterization technologies and potential strategies for developing novel photoelectrodes and advanced photoelectrochemical water splitting devices are demonstrated.     

Influence of nickel oxide nanolayer and doping in organic light-emitting devices

Here we report the effect of introducing nickel oxide (NiO) on the performance of organic light-emitting devices (OLEDs) based on small molecules. For the purpose of aligning the NiO deposition with the conventional OLED process, we employed a thermal evaporation method using the NiO powders. To understand the influence of the NiO introduction, we fabricated two types of devices: (1) OLED with the NiO nanolayer and (2) OLED with the NiO-doped hole transport layer. Results show that the NiO introduction improved the hole injection in both types of OLED. However, the device with the NiO nanolayer exhibited greatly improved efficiency, whereas the efficiency was significantly lowered for the device with the NiO-doped hole transport layer.     

Degradability of Polymers for Implantable Biomedical Devices

Many key components of implantable medical devices are made from polymeric materials. The functions of these materials include structural support, electrical insulation, protection of other materials from the environment of the body, and biocompatibility, as well as other things such as delivery of a therapeutic drug. In such roles, the stability and integrity of the polymer, over what can be a very long period of time, is very important. For most of these functions, stability over time is desired, but in other cases, the opposite–the degradation and disappearance of the polymer over time is required. In either case, it is important to understand both the chemistry that can lead to the degradation of polymers as well as the kinetics that controls these reactions. Hydrolysis and oxidation are the two classes of reactions that lead to the breaking down of polymers. Both are discussed in detail in the context of the environmental factors that impact the utility of various polymers for medical device applications. Understanding the chemistry and kinetics allows prediction of stability as well as explanations for observations such as porosity and the unexpected behavior of polymeric composite materials in some situations. In the last part, physical degradation such interfacial delamination in composites is discussed.     

夹钳数量对双曲顶件拉伸成形的影响

利用有限元软件ABAQUS,以双曲顶件为研究对象,建立不同夹钳数量下的拉伸成形有限元模型,分析夹钳数量对板料成形效果的影响.结果表明:拉形力相同时,随着夹钳数量的增加,板料的成形性更好.整体夹钳和5个夹钳拉伸成形的板料均未完全贴模,后者的贴模程度优于前者;10个和15个夹钳的拉伸成形板料完全贴模,后者得到的成形件的应变...     

溅射方法和基体材料对氧化钛薄膜微观结构的影响

目的研究不同溅射方法和基体材料对沉积氧化钛薄膜的晶体结构、化学价态、表面形貌的影响。方法采用高功率脉冲磁控溅射(HPPMS)和直流磁控溅射(DCMS)在316L不锈钢和硅片表面制备了氧化钛薄膜。采用等离子光发射谱检测了沉积薄膜时的等离子体特征。采用X射线衍射仪(XRD)、X射线光电子能谱(XPS)、原子力显微镜(AFM)和扫描电子显微镜(SEM),分别评价氧化钛薄膜的晶体结构、化学价态、晶粒尺寸和表面粗糙度。结果等离子体特征显示,沉积氧化钛薄膜时,HPPMS比DCMS具有更高的离化率和等离子体密度。XRD结果显示,在相同的平均溅射功率下,采用HPPMS和DCMS方法,均在不锈钢表面制备出纯金红石结构的氧化钛薄膜,而在硅片表面得到的氧化钛薄膜为金红石、锐钛矿混合结构,且采用HPPMS比DCMS技术制备的氧化钛薄膜含有更高的金红石含量。XPS结果显示,两种方法在所有基体表面均制备出了含有氧缺位的氧化钛薄膜。采用HPPMS和DCMS制备氧化钛薄膜时,不锈钢基体沉积的薄膜中,Ti3+/Ti4+比值均高于Si基体上的薄膜。SEM和硬度测试结果显示,HPPMS制备的氧化钛薄膜为等轴晶,晶粒较小,硬度较高。DCMS制备的氧化钛薄膜具有柱状晶的结构,晶粒较大。AFM的结果显示,采用不同溅射方法制备的氧化钛薄膜表面粗糙度没有明显差别。结论不同溅射方法和基体材料导致了薄膜沉积时样品表面离子轰击能量的差异,因此影响了氧化钛薄膜的晶体结构、化学价态和晶粒尺寸。     

叶片模具型面逆向设计方法

针对我国叶片精锻模具逆向设计精度低、设计过程复杂等问题,运用VS自定义算法,实现了对模具型面点云数据的分块化处理,提高了数据点处理精度;运用UG二次开发,实现了曲线曲面的参数化建模和模具模型的检测与自动化修正,并运用Menu Script菜单脚本,实现点云数据处理、模具逆向建模以及检测与修正在UG中的集成,提高了模具逆向设计效率;最后运用Deform-3D软件对叶片模具设计的某些参数进行了验证,并通过工程实例对逆向设计的叶片模具进行了检测分析。     

齿形件精冲成形时的齿顶塌角分析及措施

针对精冲成形齿形件时的齿顶塌角问题,首先分析了齿形零件的几何特征及精冲成形特点,并分析了这些特征与齿形零件精冲时齿顶塌角的关系;将精冲变形区分为2个核心变形区和2个变形影响区,对核心变形区Ⅰ精冲塌角的形成过程进行了分析。然后,通过有限元模拟软件Deform-3D,找出齿顶塌角处材料在成形过程中的流动规律。结果表明:齿顶处A面轮廓附近的材料沿齿顶径向运动,一部分材料流向齿顶外侧;齿廓B、C侧附近的材料沿其轮廓线所指向的齿顶方向流动。再次,全面分析了影响精冲齿顶塌角大小的各种因素,找出压边力和反顶力对塌角大小的影响规律,得出反顶力比压边力对控制塌角的效果更显著。最后,提出了在齿形零件精冲成形过程中减小或消除齿顶塌角的具体措施对策。     

DC04钢板胀形-渐进复合成形锥形件成形能力的实验研究

为了提高渐进成形过程中板料的成形极限和加工效率,提出了胀形-渐进成形的复合成形方法,通过胀形-渐进成形复合成形锥形件实验,研究了DC04钢板胀形-渐进成形复合成形锥形件和纯渐进成形锥形件的成形极限角和应变变化以及壁厚分布规律。结果表明:预成形高度为h=15 mm和h=25 mm时,复合成形零件的成形极限角分别为α极=66°和α极=69°;采用胀形-渐进成形复合成形锥形件,当胀形的最大减薄量发生在局部渐进成形区内,并且胀形和渐进成形的最大减薄量位置方向相反时,锥形件壁厚趋于均匀,提高了胀形-渐进成形的复合成形能力。     

硫磺回收装置循环水换热器的腐蚀原因分析

某石化厂硫磺回收装置的循环水换热器发生了严重腐蚀,通过分析现场腐蚀状况、腐蚀产物及循环水水质报告等对换热器腐蚀原因进行分析。结果表明:该换热器的腐蚀以点蚀为主,微生物腐蚀为辅。由于循环水中存在大量杂质离子,导致换热器内部环境变为弱碱性,引起点蚀;另外,换热器循环水中存在的少量异养菌是导致微生物腐蚀的主要原因。