Visualisation research on characteristics of the cryogenic slug flow in vertical and inclined tubes

The statistical parameters of Taylor bubbles in cryogenic slug flow along glass tube were studied experimentally for various inclination angles θ (0°–60° from the vertical direction) and four tube inner diameters D (14, 18, 25 and 32 mm) by using high speed digital camera. The distributions and mean values of initial formation position, and the length and velocity of Taylor bubbles along the tube at various inclination angles were obtained. Initial position of Taylor bubbles increases as tube inner diameter increases and the effect of tube diameter on Taylor bubble initial position becomes more obvious at θ ≥ 30°. Taylor bubble length shows an allometric decreasing trend with the increasing of tube inner diameter. The influence of inclination angle and axial position on the length and velocity of Taylor bubble in cryogenic slug flow agrees qualitatively with conventional air–water system. The maximum mean velocity of Taylor bubble occurs at 30° ≤ θ ≤ 45° and the minimum mean length of Taylor bubble occurs at 0° ≤ θ ≤ 20°. The Mean length of Taylor bubble increases along the tube for x/D ≤ 60. © 2011 Canadian Society for Chemical Engineering     

Experimental investigation on the effect of surface characterization of electrodes on the gas bubble dynamics in electrolyte flow and performance of FLA batteries by using PIV

In the flooded lead_acid batteries (FLAB), gas bubbles are initially formed on the surface of the electrodes, which are produced by electrochemical reactions, and then released into the electrolyte. In the present investigation, the effect of surface characterization of electrodes of FLAB on the gas bubble dynamic parameters in the electrolyte flow at different charging/discharging rates (C-rates) are studied utilizing particle image velocimetry (PIV) method. The results show that the capacity of FLAB have a linear behav-ior due to changes in each of the two parameters of the surface characterization of electrodes and the C-rate. At all State of charges (SOCs) of FLAB cells in different tests, increasing average roughness (Ra) and average wavelength of the roughness (ka) in the electrode surfaces, results in an increase in average bub-ble diameter and bubble rising velocity. Nevertheless, a sharp decrease in the void fraction of bubbles within the electrolyte was observed due to the increment in ka and Ra. Also, the effect of the rising move-ment of gas bubbles within the electrolyte on the average electrolyte velocity pattern in the gap between the electrodes by changing the surface characterization of electrodes are investigated in detail.     

Study on fiber structure formation in wet spinning of aliphatic polyketone using aqueous solution of complex metal salts—Characteristics of solid structure formation in drying step and its effects on superdrawing step

Solid structure formation in the drying step for wet spinning of poly(1‐oxotrimethylene) using as a solvent an aqueous solution of complex metal salts of calcium chloride/zinc chloride was studied. Because the degree of structural densification and the crystal structure both differ depending on the drying temperature, the drying temperature had a major effect on the drawing behavior and the strength achieved after drawing. With higher drying temperature, the denseness increased due to smaller voids in the dried undrawn fiber, while there was also a tendency toward higher strength with respect to the draw ratio. However, an excessively high drying temperature altered the crystal structure from a rough crystalline form to a dense crystalline form and reduced both the maximum draw ratio and strength. Mechanical cleavage of the molecular chains occurred between the ethylene groups and carbonyl groups of the main chains in the drawing step. This cleavage made it possible to suppress the inhibition of drawing due to entanglement of the molecular chains, thereby enabling superdrawing to afford a high performance fiber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 446–452, 2004     

TEMPO-NaOCl-NaBr体系选择性氧化壳聚糖及其产物的结构表征

壳聚糖的功能化改性及其生物医学等领域的应用是近年来备受人们关注的重要研究方向.文章研究了TEMPO-NaOCl-NaBr体系对不同形态壳聚糖的氧化过程及其产物的结构表征.发现NaOcl、NaOCl-NaBr、TEMPO-NaOCl和TEMPO-NaOCl-NaBr体系的氧化反应速率递增,溶胀态壳聚糖和壳聚糖纤维由于有着...     

废弃混凝土再生微粉对混凝土抗冻性能及气孔结构的影响

本文研究了利用废弃混凝土制备的再生微粉掺量、矿物掺合料复掺作用、引气剂含量等因素对混凝土抗冻性能的影响,并且通过电镜扫描、压汞法、Rapid Air等手段来分析混凝土微观结构变化与其抗冻性能之间的关系.结果表明:混凝土抗冻性能随着再生微粉掺量的增加逐步提高,当水胶比为0.35,混凝土中单掺30％再生微粉时,其抗冻次数可...     

PVC-U型材断面结构及壁厚对其焊接角最小破坏力的影响

介绍了国家和行业标准对门、窗用未增塑聚氯乙烯(PVC-U)型材壁厚和结构尺寸的规定,并详细介绍了型材壁厚、结构尺寸对焊接角最小破坏力的影响,目的在于说明门、窗用未增塑聚氯乙烯(PVC-U)型材的合理化设计的重要性。     

The formation of fibrous structure of polyamide 6 induced by the three-step forming process and its prominent reinforcement in nitrile rubber

Nitrile rubber (NBR) blends with excellent performance have always been a hot research topic in petroleum field. Due to the excellent performance and compatibility of polyamide 6 (PA6), it provides an opportunity for the preparation of high-performance NBR/PA6 blends. In this article, NBR/PA6 blends were prepared by the three-step molding process. Experimentally, it was found that PA6 has a prominent reinforcement effect in NBR matrix. The variation of this mechanical property was investigated from different aspects of the crystal structure, crystallinities, phase morphology, and so on. It can be cleared that the formation of fibrous structure of PA6 phase is the main factor for reinforcement of the polymer blends. Meanwhile, the formation mechanism of the special phase structure induced by the three-step process is deeply expounded and its structural evolution schematic is established. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47472.     

聚芳醚酮增韧环氧体系相结构的冲击韧性及模拟计算研究

采用SEM观察了热塑性聚芳醚酮(PAEK)共混增韧环氧树脂的浇注体脆断断口相形貌,统计分析了浇注体断口粒子相尺寸与PAEK含量间的关系,测试了浇铸体的冲击韧性(ak)。结果表明:随着PAEK的质量分数从23.1%增加到33.3%,热固性颗粒的粒径由1.59μm减小到0.99μm;树脂浇铸体的ak值在PAEK的质量分数为28.6%时增加到28.06 kJ/m2,然后再减小。在上述结果的基础上,通过有限元分析软件重构了该体系的三维相结构,预测了树脂体系的冲击强度并与实验结果进行了对比,二者相符性较好。     

银系磷酸锆抗菌剂晶体结构与抗菌剂制备及性能关系初探

银系磷酸锆抗菌剂就结构分为层状磷酸锆抗菌剂和立方体磷酸锆抗菌剂。两者在制备方法,抗变色性,银离子析出率及抗菌时间等多方面抗菌剂性能有所不同。本文试着从两者的晶体结构角度出发,探究两者性能差异的原因。     

Flexible cross‐linking by both pentaerythritol and polyethyleneglycol spacer and its impact on the mechanical properties and the shape memory effects of polyurethane

A series of polyurethane (PU) polymers cross‐linked laterally by pentaerythritol and polyethyleneglycol (PEG) spacers were compared with linear PU. The PU was composed of 4,4′‐methylenebis(phenylisocyanate) (MDI), poly(tetramethyleneglycol), 1,4‐butanediol (BD), pentaerythritol, and PEG‐200 as a spacer. PEG‐200 connected the pentaerythritol hydroxyl groups of two PU chains with MDI as a connecting agent. The phase separation between hard and soft segments was disrupted by the PEG crosslinking, and T_m did not change with an increase in cross‐linking content. Instead, the cross‐link density increased with an increase of pentaerythritol content. A significant increase in maximum stress compared with linear PU was attained, together with an increase in strain. The combination of both pentaerythritol and PEG‐200 in the PU resulted in the improvement of both stress and strain, unlike in the conventional cross‐linking method. The shape recovery increased to 90% and did not decrease after three test cycles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

电石法PVC生产中汞流向全面分析与污染防治

从电石法PVC生产中VCM合成的工艺流程分析汞的来源与流向,定量计算汞平衡,提出含汞废物的处置方法和污染防治措施.