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61.
Y. J. Cho P. S. Song C. G. Lee Y. Kang S. D. Kim L. T. Fan 《Chemical Engineering Communications》2005,192(3):257-271
Liquid dispersion in the radial direction was investigated in the riser of a viscous liquid-solid fluidized bed 0.102 m in diameter and 3.5 m in height. Pressure fluctuations in the riser were also measured and analyzed to examine the behavior of fluidized particles. Effects of liquid velocity (0.15-0.45 m/s), solid circulation rate (2-8 kg/m2s), particle size (1-3 mm), and liquid viscosity (0.96-38 mPas) on pressure fluctuations and the liquid radial dispersion coefficient were determined. The infinite space model was employed to obtain the radial dispersion coefficient from the radial concentration profiles of the tracer. The pressure fluctuations were analyzed by means of autocorrelation coefficient as well as power spectral density function. The dominant frequency obtained from the autocorrelation coefficient or power spectral density function of pressure fluctuations decreases with increasing liquid viscosity or liquid velocity, but it increases with increasing particle size. The liquid radial dispersion coefficient decreases with increasing liquid velocity or viscosity, but it increases as the solid circulation rate or particle size increases. The liquid radial dispersion coefficient is related closely to the resultant behavior of fluidized particles. The radial dispersion coefficient has been well correlated with operating variables in terms of dimensionless groups. 相似文献
62.
Because silica has strong filler–filler interactions, a silica‐filled rubber compound shows a poor filler dispersion compared to a carbon black‐filled one. Improvement of the filler dispersion in silica‐filled styrene–butadiene rubber (SBR) compounds was studied using low molecular weight polybutadiene (liquid PBD) with the high content of 1,2‐unit. By adding the liquid PBD to the silica‐filled SBR compound, the filler dispersion and flow property are improved. The cure time and cure rate become faster as the 1,2‐unit content of the liquid PBD increases for the compounds containing the liquid PBD. The crosslink density increases linearly with increase in the 1,2‐unit content of the liquid PBD. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3135–3140, 2003 相似文献
63.
The axial dispersion-sedimentation model is commonly used to describe the axial concentrations of solids in three phase bubble columns at low liquid velocities. When the two parameters of this model, the particle settling velocity and the solids axial dispersion coefficient, are uncoupled by the use of various assumptions, physically unrealistic values of these parameters often result. Direct experimental measurements of solids settling rates in bubbly gas-liquid mixtures were carried out. The measured mean settling velocities decreased slightly with gas flow rate and were equal to or slightly less than the single particle free settling velocity in the liquid alone. Solids axial dispersion coefficients were also obtained from the solids settling rate distribution data, and gave values considerably less than the experimental liquid axial dispersion coefficient. 相似文献
64.
Gas dispersion in a double turbine stirred tank is experimentally characterised by measuring local gas holdups and local bubble size distributions throughout the tank, for three liquid media: tap water, aqueous sulphate solution and aqueous sulphate solution with PEG. For all these media, bubble coalescence generally prevails over breakage. Where average bubble size decreases, this can be attributed to the difference in slip velocity between different sized bubbles. Most of the coalescence takes place in the turbine discharge stream.A compartment model that takes into account the combined effect of bubble coalescence and breakage is used to simulate gas dispersion. The model predicts spatial distribution of gas holdup and of average bubble size, with average bubble size at the turbines as an input. Reasonable agreement between experiment and simulation is achieved with optimisation of two parameters, one affecting mainly the slip velocity, the other related mainly to the bubble coalescence/breakage balance. Different sets of parameters are required for each of the three liquid systems under study, but are independent of stirring/aeration conditions. The model only fails to simulate the smaller average bubble diameters at the bottom of the tank. 相似文献
65.
吕廷芬 《上海电力学院学报》2010,(12)
为了测量石英晶体最大双折射率的色散特性,在椭偏光谱仪的水平透射测量模式下,通过对确定厚度的石英波片相位延迟量的精确测量,计算出了石英晶体的最大双折射率值,并进行了误差分析。结果表明:这种方法光路简单、操作方便,屏蔽了光源的不稳定性;双折射率测量精度达到了10-6,比连续偏光干涉法的测量精度提高了1个数量级;实现了对石英晶体的最大双折射率色散特性的连续光谱测量;此方法对其它双折射晶体材料的双折射率色散特性的研究也同样适用。 相似文献
66.
通过采用含时变分原理,在结合Hartree型多粒子试探波函数和Jackiw-Kerman型单粒子波函数的基础上,研究了带对称单阱非谐格点势的量子Klein-Gordon模型的声子色散关系.在满足最小测不准关系的条件下,导出了粒子的期望值所满足的运动方程,并以此得到了声子色散关系.结果表明:与经典模型相比,由于量子涨落的影响,量子模型中的有效格点势的二次方项系数增大,声子元激发的带隙变宽;二次方项系数和带隙随着量子涨落和格点势的四次方项系数的增大而增大. 相似文献
67.
以丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)以及丙烯酸(AA)为单体,聚甲基丙烯酰氧乙基三甲基氯化铵(PDMC)为分散稳定剂,2,2′-偶氮(2-脒基丙烷)二盐酸盐(V-50)为引发剂,在硫酸铵水溶液中成功制备了两性聚丙烯酰胺(am-PAM)。考察了分散稳定剂相对分子质量、反应介质pH值、反应温度以及搅拌速度对水分散体系的影响,并用红外光谱仪以及扫描电镜对产品结构进行表征。研究得到合成两性聚丙烯酰胺水分散体系的较佳工艺条件:PDMC的相对分子质量30×104~46×104,反应介质的pH5.0~6.5,反应温度55~65℃,搅拌速度75~125 r.min-1,所得体系相界面明显,颗粒呈球形。 相似文献
68.
基于光纤色散引起的脉冲展宽效应,在理论和实验上研究了有源光学电流传感器(AOCS)中宽带光源对系统输出的影响.理论结果表明:对于长度为500m的光纤,当光源谱宽在40—60nm之间变化时,多模光纤传输下的脉冲展宽范围在0.5~0.8ns,单模光纤传输下的脉冲展宽范围在2×10^-5~4×10^-5,信号衰减量对系统输出影响很小,且随光源谱宽的增加而有微弱的增加,实验与理论相符合. 相似文献
69.
70.
This paper reports on the experimental investigation carried out to evaluate fractional dispersed phase holdup for a gas‐liquid mixture in a modified multi‐stage bubble column (with contraction and expansion disks), which has been conceived, designed and fabricated as a wet scrubber for control of air pollution; in addition it has versatile use as a gas‐liquid contactor in chemical process industries. A correlation developed for predicting fractional dispersed phase holdup has been found to be encouraging and highly significant from statistical analysis. 相似文献