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101.
In close-coupled gas atomization(CCGA), the influences of melt superheat on breakup process are fundamental to obtain desired or finer powder. Based on a series of Cu atomization experiment under different superheating conditions, the influences of melt superheat on breakup process were studied. Experimental results indicate that as the melt superheat is increased to 150, 200, 250 and 300 K, the mean particle size (D50) decreases consequently to 34.9, 32.3, 30.9 and 19.7 μm. Theoretical analysis reveals that the primary breakup and secondary breakup processes are close coupled, and the melt superheat radically influences the melt properties, and plays a crucial role on governing the filming process of primary breakup and the atomization modes of secondary breakup. There exists a strong nonlinear decrease of contact angle of melt to nozzle orifice wall when the superheat is increased fi'om 250 K to 300 K, leading to a marked fall of the film thickness formed in primary breakup, and D50 of copper powders is therefore sharply reduced. However, the log-normal distribution feature of particle size has not been substantially improved. 相似文献
102.
A new method for characterization of stratified thermal energy stores (TES) that integrates both the first law and the second law concerns is presented here. The first law concern is incorporated into a quantity called energy response factor and the second law concern into an entropy generation ratio. A product of these two quantities is at the heart of the TES efficiency definitions. This approach removes the overemphasis of the existing methods either on the first or the second law of thermodynamics which often biases the characterization results. The information about the evolution of the temperature field of the system in time is the prerequisite of the new method. It may be obtained from experiments or from suitable numerical simulations. The current method can be easily integrated into computational fluid dynamic (CFD) simulations and thus facilitate CFD-based design analysis. As an example of such CFD-integrated analysis, a large-scale hot water seasonal heat store is numerically studied to identify the effects of aspect ratio, containment shape, internal structures, and containment size on their efficiency. The results suggest the effectiveness of the new method in deriving useful design insights. 相似文献
103.
T. M. Morris 《Journal of the Institute of Brewing》1987,93(1):13-17
Haze measurements have been obtained for suspensions of polystyrenelatex particles of known diameter using two light scattering instruments which measure at angles of 90° and 13° respectively. The results agree well with the theory of light scattering and demonstrate the significant effects of particle size and angle of detection upon the instrumental values for haze. This information has been used to correlate the particle size distributions of a number of beers, as measured by Coulter Counter, with the corresponding, measured haze values. 相似文献
104.
通用的回转体拉深件毛坯直径的计算公式繁琐,不蝗记忆,特别是利用中线尺寸常出现小数点使计算复杂,本文针对此问题分别推导出了利用中线尺寸和不用中线尺寸时,毛坯直径的简捷计算公式。并进行了误差分析,最后用实例对简捷计算方法的正确性给予了验证。 相似文献
105.
大中型风力发电机组可靠性研究 总被引:6,自引:2,他引:4
研究了大中型风力发电机组的可靠性,讨论了可靠性指标的分配,可靠性设计的四个重要方面、可靠性试验计算机模拟。 相似文献
106.
Effect of Particle Size on Monometallic and Bimetallic (Au,Pd)/C
on the Liquid Phase Oxidation of Glycerol 总被引:2,自引:0,他引:2
Nikolaos Dimitratos Jose Antonio Lopez-Sanchez David Lennon Francesca Porta Laura Prati Alberto Villa 《Catalysis Letters》2006,108(3-4):147-153
The influence of metal particle size of monometallic and bimetallic supported catalysts (Au, Pd, Au–Pd)/C was studied using
as a model reaction the liquid phase oxidation of glycerol. By tuning the metal particle size from 2 to 16 nm a progressive
decrease of activity and simultaneously an increase in the selectivity to sodium glycerate was observed. Moreover, the influence
of the temperature was studied and it was found that by increasing the temperature, only with a large particle size the formed
glycerate was retained and not over-oxidized to tartronate. 相似文献
107.
通过对广州市猎德污水处理厂的介绍,说明本工程厂区平面根据规划用地、工艺流程、外部及内部环境因地制宜进行布置,建筑立面造型综合考虑厂房的不同使用功能,力求打破以往的工业建筑模式,建成处处以人为本的生态花园式厂房。 相似文献
108.
109.
激光粒度分析仪测定氢氧化铝细颗粒方法的探讨 总被引:1,自引:0,他引:1
针对马尔文2000型激光粒度分析仪在氢氧化铝分析中对25μm粒径以下细颗粒的分析不太敏感,难以满足氧化铝生产分解过程对粒度控制的要求,对试验样品采用一些非常规的特殊处理方法,以提高细小颗粒在处理过样品中所占的体积百分比;研究了不同的样品处理方式对分析结果的影响。试验结果表明,只有对洗涤、过滤后的湿样进行分析,才能对分解料浆样品中的细颗粒的粒度分布进行准确地分析,得到满足试验和生产过程控制精度的结果。 相似文献
110.
The paper presents a computational approach and numerical data which facilitate the use of the smeared-tip method for cohesive fracture in large enough structures. In the recently developed K-version of the smeared tip method, the large-size asymptotic profile of the stress intensity factor density along a cohesive crack is considered as a material characteristic, which is uniquely related to the softening stress-displacement law of the cohesive crack. After reviewing the K-version, an accurate and efficient numerical algorithm for the computation of this asymptotic profile is presented. The algorithm is based on solving a singular Abel's integral equation. The profiles corresponding to various typical softening stress-displacement laws of the cohesive crack model are computed, tabulated and plotted. The profiles for a certain range of other typical softening laws can be approximately obtained by interpolation from the tables. Knowing the profile, one can obtain with the smeared-tip method an analytical expression for the large-size solution to fracture problems, including the first two asymptotic terms of the size effect law. Consequently, numerical solutions of the integral equations of the cohesive crack model as well as finite element simulations of the cohesive crack are made superfluous. However, when the fracture process zone is attached to a notch or to the body surface and the cohesive zone ends with a stress jump, the solution is expected to be accurate only for large-enough structures. 相似文献