ECT研究浅层鼓泡塔中的气含率行为

在内径0.14 m的浅层鼓泡塔内采用电容层析成像技术(ECT)研究了孔口气速和孔径大小对鼓泡塔气含率行为的影响。实验选用空气-去离子水体系,在轴向高度4.75、17.75 cm处同时测定气含率曲线,孔口气速范围为4~186 m/s。以单管为气体分布器,开孔率和孔径范围分别为0.14%~1.31%和5.3~16.0 mm。实验结果表明:气含率随气速的增大而增大;当孔径d0=10.5 mm,孔口气速大于19 m/s时,气含率曲线斜率发生变化,一定程度上表明此时的流型由鼓泡流开始向射流转变;在相同孔口气速下,气含率随孔径的增大而增大,且能谱图主频大小和谱宽也随孔径的增大而增大;得到了鼓泡过程中流型转变孔口气速uN,trans,发现uN,trans随孔径增大而减小,并对比文献认为对于空气-水体系,d0=10 mm可能是区分大小孔径的合理标准。     

鼓泡塔中液相混合时间的影响因素

分别以自来水、醋酸-去离子水溶液(醋酸质量分数分别为1%、5%和10%)为液相,空气为气相,在直径分别为200 mm和400 mm的鼓泡塔内,采用4种气体分布器(单管、四管、分布板和微孔板),考察当表观气速Ug为0.006~0.250 m/s,鼓泡塔高径比H/D为0.8~7.0时,鼓泡塔有无内构件条件下的液相混合时间。结果表明:对于空气-水体系,当表观气速较低时,增加表观气速,液相混合时间明显缩短,表观气速对混合时间的影响逐渐消失,混合时间随鼓泡塔高径比的增加而迅速增加;当以醋酸水溶液为液相时,在特定表观气速(0.10 m/s)下,体系呈现出发泡性质,tm-Ug曲线出现"跳跃点",该点处液相混合时间为相同条件下自来水体系的2~3倍;高于或低于此特定表观气速,两种体系混合时间的差别较小。即在不发泡条件下,液体离子强度、表面张力对气液相混合不足以产生显著影响。增加导流筒可以使液相混合时间延长。引入横向换热管后,混合时间延长,且表观气速的影响范围变大,表观气速对混合时间的影响不是单调关系,存在极值点。     

下喷式环流生化反应器性能初探

本文以摸拟生物流体——不同浓度的 CMC 水溶液-空气为实验体系,考察了气速、液速等操作条件以及体系物性对下喷式环流反应器流体力学和传递特性的影响,提出了气含率及容积传氧系数的计算关联式ε_G=1.605n~(5·080)·((ρ_Gμ_G)/(ρ_Lμ_L))~(-0·3784).Fr_G~(0·3078)·Fr_L~(0·1918)Sh=8.669×10~6 n~(1·589).Sc~(0·3537).Re~(0·4718).Fr_G~(0·09944).Fr_L~(1·403)为该反应路的进一步研究及其工程放大设计提供了依据。     

用耐温耐压测氧探头测定邻二甲苯空气氧化鼓泡塔中的传质和反应动力学

用耐温耐压银一铅原电池型测氧探头连续测定了邻二甲苯空气氧化鼓泡塔中的氧含量,从而计算了带反应的传质系数、并建立了反应动力学方程式。发现120℃体积传质系数K_(La)基本上不随氧化深度而改变。在空塔气速u_g～0.05 m/s的条件下,平均约为1377小时~(-1)。在钴催化剂含量为160ppm时(120℃)反应动力学方程式可表示为: _(c-x)=((4.16-24.91CopA)×10~(-3)C_(o-x))/(1+0.65×10~(-5))(C_(o-x)/Co_2)     

鼓泡反应器内环流初探——鼓泡反应塔研究之二

本文是《鼓泡反应塔的气泡特性》一文中所提出的“循环流”的进一步研究,并做为《鼓泡反应塔的气泡特性》一文的续篇而提出来的,故命名为《鼓泡反应器内环流的初探》。在空塔气速V_(SG)=1～7 cm/s范围内,用空气——水体系,研究了内装同心导流筒的鼓泡反应器(以下简称“环流反应器”)的流动模型和传质,并与无内件鼓泡器(以下简称“空塔”)和机械搅拌的鼓泡器(以下简称“搅拌鼓泡器”)进行了比较。发现,环流反应器的流况可以用带死区和短路的理想混合模型来描述,并求出了模型参数h和m;环流反应器的容积传质系数k_La大于空塔的k_La值;在V_(SG)>4cm/s的条件下,环流反应器的k_La也大于搅拌鼓泡器的k_La。对环流反应器内D_E/D影响的研究表明,D_E/D=0.58时,传质情况最好。     

以鲍尔环为内构件的鼓泡塔反应器的流体力学性能

对二甲苯氧化合成对苯二甲酸常用鼓泡塔作为气液反应器,以填料为内构件可以强化鼓泡塔反应器的气液接触状况,从而提高反应速率。以金属鲍尔环为内构件,考察鼓泡塔反应器的气液接触状况,采用高速摄像技术对气泡群进行图像分析,同时利用体积膨胀法测定气含率,研究不同型号鲍尔环作用下的气含率、气泡尺寸和粒径分布。结果表明,Φ25鲍尔环对气泡的切割效果最好,气泡的尺寸分布较为集中,主要处于3.00～6.00 mm之间,Sauter平均直径随气速增大而增大,并在高气速下趋于平缓;鼓泡塔反应器的气含率随气速增大而增大,且鲍尔环尺寸越小气含率越大。利用实验数据进行非线性回归,得到在实验气速范围内气含率与气泡Sauter平均直径、比表面积的关联式,计算值与实验结果较为吻合。     

氧热法电石合成淤浆鼓泡床反应器的流动特性

针对氧热法电石合成的电石吸热反应和炭燃烧放热耦合特点,本文设计并研究了适用该过程的三相淤浆鼓泡床反应器。采用空气-水-氯化聚氯乙烯（CPVC）模拟物系,实测了不同表观气速、固体颗粒进料量和静液高度下淤浆鼓泡床床层中局部平均气含率、固含率轴向分布和大、小两类气泡的分布。结果表明表观气速越大,局部平均气含率越大;固体颗粒的加入减小了床层局部平均气含率。当Ug在0.136~0.196m/s之间时,固含率轴向分布随表观气速增大趋于均匀;固体颗粒进料量越小则固含率沿轴向分布越均匀。随着表观气速的增加,小气泡含量逐渐增加,大气泡含量逐渐减小;随着静液高度的增加,大气泡含量均是先增大后减小。上述结果表明电石生成反应与燃烧供热反应原位耦合于淤浆鼓泡床中是可行的。     

CFD研究短导流筒对鼓泡塔流体动力学的影响

采用双流体模型及k-ε湍流模型模拟研究了短导流筒内构件对鼓泡塔流体力学性能的影响。共模拟了4种鼓泡塔,即简单鼓泡塔和3种安装有导流筒的鼓泡塔,塔径D均为190 mm,导流筒离底距离分别为0.5D、1.0D、1.5D,导流筒直径为0.7D,长度为1.0D。结果表明,简单鼓泡塔模拟结果与文献实验值吻合较好;安装导流筒后,导流筒下游气含率和轴向液相速度径向分布更为均匀,并且在不降低整体气含率的情况下,显著提高了鼓泡塔底部的液相轴向脉动速度,将有利于三相鼓泡塔内的固体颗粒悬浮。     

一个素变量混合幂丢番图不等式

目的证明素数p_j对不等式︱λ_1p_1+λ_2p_2~2+λ_3p_3~2+λ_4p_4~k-v︱(maxp_j)~(-1/8σ(k)+ε)有无穷多个解,其中k是大于或等于3的正整数,ε0,v是任意给定的实数,σ(k)=min(2~(s(k)-1),1/2(s(k)+1)),s(k)=[k+1/2],假设λ_1,λ_2,λ_3,λ_4是非零的实数,并且λ_1/λ_2是无理数。方法使用Davenport-Heilbronn方法来改进这一结果。结果与结论 maxp_j的指数估计为-1/8σ(k)+ε。     

气液在高H/D比搅拌式鼓泡塔中气含率及压降的研究

利用 ф2 8mm玻璃搅拌式鼓泡塔 ,在高径比H/D =5 0、分段数N =3～ 2 3和变搅拌转数n下测定空气———水系统在塔内作并流流动时的气含率与压降 ,分析了两相流气速、液速、分段数及搅拌转数对气含率和压降的影响 ,所得经验关联式与实验数据进行了较好的吻合 .结果表明该装置具有延长气泡停留时间、提高气含率及利于界面传质的优点 .     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with