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Table of Content
25 August 1999, Volume 50 Issue 4
    化工学报
    ANALYSIS OF EVAPORATION HEAT TRANSFER IN CAPILLARY TUBES
    Wang Jinliang(Institute of Engineering Thermaphysics, Chinese Academy of Sciences , Beijing 100080)
    1999, 50(4):  435-442. 
    Abstract ( 565 )   PDF (407KB) ( 127 )  
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    The paper deals with evaporation heat transfer in micro/mini size capillary tubes with theoretical analysis and practical calculations. The evaporating meniscus in capillary tubes can be divided into three regions: equilibrium thin film region, transition film region and intrinsic meniscus region. Heat and mass transport occurs on the transition film region and intrinsic meniscus region. The calculation methods for heat transfer performance are given. The results of calculation show that there exist high heat transfer coefficients in the transition film region and the influence of the capillary tube diameter on heat transfer performance mainly depends on the intrinsic meniscus region. The average heat transfer coefficient decreases with increasing diameter of capillary tubes.
    COUPLING SIMULATION MODEL OF MELT FLOW AND FIBER ORIENTATION FOR FIBER REINFORCED PLASTICS IN INJECTION MOLDING
    Lin Lanfen and Dong Jinxiang(Artificial Intelligence Institute, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  443-448. 
    Abstract ( 582 )   PDF (303KB) ( 153 )  
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    In this paper, a coupling simulation model is presented on the basis of the analysis of the features of melt flow and fiber orientation in injection molding. The proposed model can simultaneously simulate the asymmetric melt flow with compressible fluid during the filling and post-filling stages and complex three-dimensional fiber orientation behavior induced by melt flow, by taking account of the variation of flow type, rheologic properties and constitutive equation caused by fiber existence and orientation.
    NUMERICAL STUDY ON CHAOTIC MIXING CAUSED BY SECONDARY FLOW
    Wang Linxiang, Chen Ying and Lu Yongxiang( State Key Laboratory for Fluid Power Transmission & Control, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  449-455. 
    Abstract ( 622 )   PDF (603KB) ( 390 )  
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    The secondary flow in a twisted curved pipe is studied by using Gelarkin method together with spectral method, and the secondary approximating solution of the velocity profile in the cross - section is given. Based on this velocity profile, the nonlinear mapping between the cross-sections is studied by numerical integration. It is found that the periodic pair-vortex induced from the secondary flow resulted in a chaotic mapping, which stretch and fold the fluid units in an exponential way, and mix the fluid in the pipe efficiently. The result is displayed by numerical simulation and experimental study.
    KINETIC MODEL OF FREE RADICAL POLYMERIZATION INCLUDING DIFFUSION PHENOMENA
    Huang Qishan, Weng Zhixue, Huang Zhiming and Pan Zuren(Institute of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  456-462. 
    Abstract ( 613 )   PDF (336KB) ( 127 )  
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    Based on free volume and chemical reaction kinetic theories, a kinetic model of free radical polymerization including diffusion phenomena was established. Unsteady process-cage effect which could affect initiator efficiency, and mass centre translation diffusion, segment rearrangement diffusion and reaction diffusion of the radical were considered. The volume shrinkage and exceeding free volume were considered also. This model was applied to the simulation of styrene bulk polymerization and agreed well with the experimental result.
    MEASURING DYNAMIC SURFACE TENSION OF SURFACTANT SOLUTIONS BY USING GROWING BUBBLE METHOD
    Wang Zhilong, Guo Hongyu and Li Tongming ( Department of Chemical Engineering, Cheng Haojun and Lai Kewei(Department of Computer Science,Tianjin University, Tianjin 300072)
    1999, 50(4):  463-468. 
    Abstract ( 624 )   PDF (380KB) ( 178 )  
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    A technique for measuring dynamic surface tensions, which is based on the theoretical analysis on a growing bubble, is proposed. The growing process of the bubble is captured by video-image technique. An edge-tracing algorithm using a local threshold and profile optimization is applied to determining the shape of the growing bubble. A device for measuring the dynamic surface tension from the profile of a growing bubble is set up, so that the dynamic surface tension can be determined directly as a function of time. The dynamic surface tensions of sodium dodecyl sulfate (SDS) solutions are also measured.
    TWO - DIMENSIONAL HETEROGENEOUS MASS TRANSFER MODEL AND ITS SOLUTION FOR GAS-LIQUID-LIQUID THREE-PHASE SYSTEM
    Lin Cheng, Zhou Ming and Xu Chunjian( Chemical Engineering Research Center, Tumjin University, Tianjin 300072)
    1999, 50(4):  469-476. 
    Abstract ( 508 )   PDF (404KB) ( 159 )  
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    In this paper, a new axisymmetrical two-dimensional heterogeneous mass transfer model describing gas-liquid mass transfer enhancement by a dispersed liquid phase is established in the cylindrical coordinate system. The calculation is fast and effective, and the calculated results are in fair agreement with the data available in the literature.
    PRESSURE FLUCTUATIONS ANALYSIS OF GAS-SOLID FLUIDIZED BED USING THE WIGNER DISTRIBUTION
    Huang Hai, Huang Yilun and Zhang Weidong(Department of Instnimentawn Engineering, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  477-482. 
    Abstract ( 671 )   PDF (316KB) ( 199 )  
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    In this paper, the signal s strong non-stationary feature is demonstrated with time-frequency two-dimensional analysis by using the Wigner Distribution (WD) for pressure fluctuation signal in gas-solid fluidized beds. By a parameter defined as the Local Peak Weighted Average (LPWA) in WD space, the effect of velocity and probe height of fluidized beds on LPWA of pressure fluctuation is shown experimentally. The results indicate that the LPWA has much better reproducibility and accuracy than the major frequency of power spectral density in reflecting the properties of bubble phase.
    LIQUID-LIQUID EQUILIBRIA AND CONSOLUTE PHENOMENA
    Hu Yujun, Hei Encheng and Liu Guojie(Department of Chemistry, East China University of Science and Technology, Shanghai 200237)
    1999, 50(4):  483-490. 
    Abstract ( 683 )   PDF (352KB) ( 210 )  
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    On the basis of the generalized Gibbs free energy model for mixing of liquids proposed by this work, the equations of binodal, spinodal and critical point for LLE are established, which are applicable not only to liquid mixtures of small molecules, but also to polymer solutions. The results of calculation show that they can be satisfactorily used to describe a variety of LLE and consolute phenomena.
    MOLECULAR DYNAMICS SIMULATION FOR INFINITE DILUTE DIFFUSION COEFFICIENTS OF ORGANIC COMPOUNDS IN SUPERCRITICAL CARBON DIOXIDE
    Zhou Jian, Lu Xiaohua, Wang Yanru and Shi Jun( Department of Chemical Engineering, Nanjing University of Chemical Technology, Nanjing 210009)
    1999, 50(4):  491-499. 
    Abstract ( 661 )   PDF (427KB) ( 165 )  
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    Lennard-Jones potential parameters of thirty-eight organic compounds were evaluated by combining critical constants experimentally determined or estimated by Joback/Lydersen methods with the reduced equation of state of Lennard-Jones fluid according to corresponding state principle. Molecular dynamics simulations of solute infinite dilute diffusion coefficients of practical organic compounds in supercritical carbon dioxide (313.15 K, 16 MPa) were then performed by using the potential parameters and simple Lorentz-Berthelot combining rules. It was shown that the simulation results predicted by molecular dynamics simulation were accurate enough for preliminary process design.
    NEURAL NETWORK MODELING AND GENETIC ALGORITHM FOR OPTIMIZING FORMULATION OF CATALYSTS
    Han Liqun(Department of Automatic Engineering, Beijing University of Light Industry, Beijing 100037 )
    1999, 50(4):  500-504. 
    Abstract ( 497 )   PDF (286KB) ( 140 )  
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    Neural network is used for the modeling of experiment data. Based on simulation data from the neural network, GA is applied to optimize the formulation of catalysts. The optimizing formulations are proved by experiments and it is identified that the algorithm is practicable . GA can also be used in optimizing formulations and optimizing chemical processes.
    INFLUENCE OF FLUID FLOW ON FORCES ACTING ON DROPLET AND EMULSIFICATION RESULTS IN MEMBRANE EMULSIFICATION PROCESS
    Wang Zhi and Wang Shichang ( Chemical Engineering Research Center, Tianjin University, Tianjin 300072) Schroeder V. and Schubert H.(Institute of Food Process Engineering,Karlsruhe University, D-76128 Karlsruhe, Germany)
    1999, 50(4):  505-513. 
    Abstract ( 680 )   PDF (460KB) ( 165 )  
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    The flow regime of continuous phase and disperse phase and the forces acting on droplets of disperse phase in membrane emulsification were analyzed. It showed that the flow regime and the forces were closely related to each other. Calculation indicated that the interfacial tension force, static pressure force, viscous drag force and dynamic lift force were the main forces acting on the droplets. The formation process of the droplet was studied . The effects of wall shear stress and trans-membrane pressure on disperse phase permeation flux and mean droplet diameter were investigated by experiments. On the basis of calculation and experiments , the influence of fluid flow on membrane emulsification results was discussed.
    CHEMICAL CHANGES WITHIN OCCLUDED CORROSION CELL OF MILD STEEL IN NaCl SOLUTION
    Xu Chunchun, Fu Xiaoping and Liu Youping(Department of Applied chemistry, Beijing University of Chemical Technology, Beijing 100029)
    1999, 50(4):  514-518. 
    Abstract ( 656 )   PDF (276KB) ( 110 )  
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    A simulated occluded corrosion cell (OCC) was used to study the chemical changes within corrosion cracks or crevices of mild steel (A3) in 0.01 mol·L-1 NaCl solution at 50 掳C . It was found that as anodic currents passing the cell, the pH value fell quickly at the beginning while slowly after it reached about 6, which was proportional to the quantity of passing electricity. Meanwhile the Cl- migrated into occluded cell. The Cl- migration was proportional to the time of current flowing, and a linear relation also existed between Cl- migration per mm2 of anode area per hour and current intensity, while for each mol Cl- migrated almost always 1.5~1.6 F of electricity passed. This relationship did not change whatever the current density and the time were.
    PREPARATION OF MONODISPERSED HYDROUS-ZIRCONIA NANOPARTICLES
    Wang Xin ( College of Material Science and Engineering* Shandong University of Technology, Jinan 250061) Li Zhenjiang, Yang Fengke and Hou Yaoyong(Laboratory of High - Tech Ceramics , Qingdao Instituteof Chemical Engineering, Qingdao 266042)Zhou Yu( Colle
    1999, 50(4):  519-523. 
    Abstract ( 866 )   PDF (405KB) ( 392 )  
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    Nanosized hydrous-zirconia sol was prepared by heating a zirconyl chloride solution with an alcohol-water mixture as the solvent and hydroxypropyl cellulose (HPC) as a dispersant in microwave oven. The sol could be transformed into m-ZiO2 and a litde of t-ZrO2 powders after being dried and calcined.The mean particle sizes of ZrO2·nh2O increase as ZrOCl2 concentration increases.The effects of HPC concentration and heating means on size and size distribution of resulting particles were analyzed.
    ADSORPTION EQUILIBRIA OF XYLENE/TOLUENE ISOMERS ON KY ZEOLITE UNDER LOW PRESSURE
    Chen Zhongxiu, Su Yun, Lu Jiangang and Ding Tongfu(Department of Chemical Engineering, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  524-529. 
    Abstract ( 599 )   PDF (282KB) ( 127 )  
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    The adsorption equilibria of p-xylene, m-xylene, o-xylene and toluene on KY zeolite were measured under temperature range (303.15~443.15K) and low pressure (3.47~2116.6 Pa) by CAHN2000 Electrobalance. All the experimental data obtained in this work can be fitted as a generalized characteristic curve of Polanyi adsorption potential theory by using the parameter of the initial heat of adsorption, which is estimated reasonably.
    ENZYMATIC RESOLUTION OF N-ACETYL-D,L-PHENYLALANINE ETHYL ESTER BY MEMBRANE REACTION-EXTRACTION PROCESS
    Jiang Zhongyi, Qiu Liqin and Chen Hongfang(School of Chemical Engineering and Technology, Turnjin University, Tianjin 300072)
    1999, 50(4):  530-534. 
    Abstract ( 660 )   PDF (287KB) ( 335 )  
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    In recognition of the importance of chirality to biological activity as well as the significance of integration to process efficiency, this paper presents a novel way for the production of L - phenylalanine by enzymatic resolution of N-acetyl-D, L-phenylalanine ethyl ester in a membrane reaction-extractor. .The effects of operation conditions on process performance evaluated by optical purity and yield of target product were investigated and satisfactory results were obtained.
    CONDENSATION HEAT TRANSFER ENHANCEMENT WITH DROPWISE AND FILM COEXISTING CONDENSATION SURFACES
    Ma Xuehu, Xu Dunqi and Lin Jifang ( Department of Chemical Engineering, Dalian University of Technology, Dalian 116012)Wang Buxuan( Department of Thermal Engineering,Tsinghua University, Beijing 100084)
    1999, 50(4):  535-540. 
    Abstract ( 603 )   PDF (403KB) ( 194 )  
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    With six surfaces prepared for different surface division patterns, steam condensation heat transfer characteristics on dropwise and film coexisting surfaces were investigated experimentally under atmospheric pressure. Dropwise condensation was promoted with ultrathin polytetrafluoroethylene (FIFE) film, which was prepared by the dynamic ion-beam mixed implantation (DIMI) method. It was found that the condensation phenomena at the interconnecting section between dropwise and film condensation parts were quite different for the different relative position of dropwise and film condensation parts. Experimental results revealed that condensation heat transfer characteristics were greatly influenced by the surface division pattern and the relative area ratio of dropwise and film condensation parts. The enhancement mechanism of condensation heat transfer was discussed accordingly.
    DC CONDUCTIVITY INSTRUMENT FOR MEASURING LIQUID RATES IN MULTIPHASE FLOW
    Wang Yiping, Zhang Jinli, Wen Jianping, Li Wei and Hu Zongding( School of Chemical Engineering, Tianjin University, Tianjin 300072)
    1999, 50(4):  541-545. 
    Abstract ( 596 )   PDF (304KB) ( 140 )  
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    A DC conductivity instrument to measure liquid rates in multiphase flow was developed and researched. The material, size, seal and shape of the probe were optimized. The effects of temperature and fluid conductivity on instrument performance were investigated to determine impulse form and instrument circuit. The liquid rate distribution in a reverse jet loop bioreactor was measured by this instrument, and the results reveal the reliability of this method.
    KINETICS OF CRYSTALLIZATION OF XYLOSE
    Wang Longhu(National Laboratory of Secondary Resources Chemical Engineering, Zhejiang University, Hangzhou 310027)
    1999, 50(4):  546-551. 
    Abstract ( 625 )   PDF (279KB) ( 216 )  
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    Steady operation of crystallization of xylose was run successfully to simulate industrial process in a 5.0L experimental continuous cooling crystallizer with a clear liquor overflow and the crystal suspension density was acceptable for industry. The crystal size distribution(CSD) of products was analyzed with population balance, which set up the kinetics equation of crystallization of xylose from aqueous solution
    GENERAL INTEGRAL MODEL OF TWO-PHASE FLOW IN CAPILLARY TUBES
    Zhang Chunlu, Ding Guoliang and Li Hao(Department of Refrigeration and Cyrogenics Engineering, Shanghai Jiaotong University, Shanghai 200030)
    1999, 50(4):  552-557. 
    Abstract ( 511 )   PDF (321KB) ( 106 )  
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    An accurate and simplified model of flow characteristics in capillary tubes is necessary for intensive study on the system performance of refrigeration plants equipped with capillary tubes. Especially, the modelling of two-phase flow in capillary tubes is important and difficult. In this paper, a novel general integral model of two-phase flow in capillary tubes is developed. The comparison with the distributed-parameter model of capillary tube using the refrigerants R12, R134a and R600a as working fluids turns out to be satisfactory. The results show that the recommended integral model is within 3.4% maximum deviation and 1% mean deviation. In computation speed, it is at least one order of magnitude faster than the distributed - parameter model.
    EXPERIMENTAL INVESTIGATION INTO DEFLAGRATIONS OF COMBUSTRIAL VAPOR CLOUDS
    Ding Xinwei, Li Zhiyi and Li Yingbo(College of Chemical Engineering, Dalian University of Technology, Dalian 116012)
    1999, 50(4):  558-562. 
    Abstract ( 595 )   PDF (318KB) ( 241 )  
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    Experimental investigations into deflagration of approximate - quiescent state and pre-mixed combustrial vapor cloud were conducted. The overpressure distributions of hemispheric mixtured vapor clouds with diameters 1, 2 and 3m respectively were experimentally measured. The pressure time histories (p-t curves) at different positions were given. The characteristics of deflagration overpressure were discussed. The results can be used to verify theoretical methods and provide reference for further research.
    SIMULATION OF DISTILLATION PROCESS WITH CHEMICAL REACTIONS
    Qi Zhiwen, Sun Haijun, Shi Junmin, Zhang Ruisheng and Yu Zunhong(Institute of Clean Coal Technology, East China University of Science and Technology, Shanghai 200237)
    1999, 50(4):  563-567. 
    Abstract ( 649 )   PDF (241KB) ( 103 )  
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    A method is presented to transform the equations describing steady reactive distillation with chemical reactions and inert components into a new set of equations. The formulating style of the new model is similar to traditional distillation model. Moreover, an algorithm which is based on the modified Newton-Raphson method is developed to solve the simultaneous equations. The reactive distillation process for separating o-and p-xylene is simulated as numerical example.
    EFFECT OF POLYMER ADDITIVES ON COHERENT STRUCTURES IN A MIXING LAYER
    Lin Jianzhong ( Department of Mechanics , Zhejiang University/ Hangzhou Institute of Applied Engineering, Hangzhou 310027) Shao Xueming and Yu Zhaosheng (State Key Laboratory of Fluid Transmission and Control/Departmentof Mechanics, Zhejiang University,
    1999, 50(4):  568-572. 
    Abstract ( 693 )   PDF (280KB) ( 162 )  
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    The evolution of coherent structures in a 2-D time-developing mixing layer of the Oldroyd-B fluids are examined numerically. The results indicate that adding polymer to the Newtonian fluids will cause stronger vorticity diffusion, accompanied with weaker fundamental and subharmonical perturbations,less intense vortex roll-up and pairing and slower rotational motion of pairing vortices. When Weissenberg number is up to 10, the vorticity gradients are enhanced and even the vorticity with opposite sign to the mean vorticity appears at the region where there is a build - up of polymer first normal stress difference. The vorticity with opposite sign results in the absence of the usual quasi - steady state of the primary vortex, and disappears due to the collapse of polymer normal stress difference if there exist pairing modes. The time when the consecutive rollers are completely coalesced into one is delayed in the viscoelatic mixing layer compared to the Newtonian one of the same total viscosity.
    APPLICATION OF MORPHOLOGICAL ANALYSIS TO MYCELIA GROWTH
    Yang Kui, Wang Jifen, Wang Fudong, Duan Shiduo and Zhang Liu( Department of Chemistry, Department of Computer , Institute of Chemical Engineering , Tianjin University, Tianjin 300072)
    1999, 50(4):  573-576. 
    Abstract ( 617 )   PDF (273KB) ( 113 )  
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    Computer aid in the study of biotransformation process is a new approach to comparatively comprehensive understanding of the course of mycelia life. On the basis of fractal and spatial gray level co - occurrence matrix models, is possible to describe the mycelial morphology quantitatively by taking advantage of Computer Image Texture Analysis Technique. Plotting the calculated fractal dimension and texture entropy features from the morphological images obtained at different phases of growth, gives a clear correlation, that is the dependency of the mycelial morphology on the cultivation conditions and stages.