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Table of Content
25 April 2002, Volume 53 Issue 4
    研究论文
    ELECTROOSMOSIS ENHANCED INTRAPARTICLE LIQUID FLOW AND MASS TRANSPORT
    LI Chen;LIU Zheng;YUAN Naiju
    2002, 53(4):  331-337. 
    Abstract ( 629 )   PDF (265KB) ( 248 )  
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    A mathematical model describing the intraparticle flow contributed by Poiseuille flow and electroosmosis in the electrochromatography was established, which showed that the contribution of electroosmotic flux became dominant when the pore diameter to particle diameter decreased. A new concept in terms of effective diffusivity was proposed to quantify the electroosmosis enhanced intraparticle mass transport. The height equivalent of a theoretical plate (HETP) of electrochromatography was calculated as function of the effective diffusivity. The effects of Poiseuille flow and electroosmosis on the magnitude of HETP was investigated, respectively. It was shown that enhancement of intraparticle mass transport by Poiseuille flow, as shown by the reduction of the magnitude of HETP, could only obtained for those large pore particles characterized by pore diameter over 500 nm. While the introduction of intraparticle electroosmosis led to the increase in the effective diffusivity and the reduction of the HETP, both of which were dependent on electric field strength and were independent of pore diameter. Prediction of the breakthrough behavior of electrochromatography was attempted using the model developed by Yoshida. The predicted breakthrough curve as a function of the electric field strength was in good consistency with those experimental results obtained in different electrochromatography systems. This demonstrated the validity of the theoretical results obtained by the present study.
    MATHEMATICAL MODEL FOR PREDICTION OF SOLVENT DIFFUSION IN AMORPHOUS GLASSY POLYMER
    WANG Baoguo;Takeo Yamaguchi;Shinichi Nakao
    2002, 53(4):  338-343. 
    Abstract ( 731 )   PDF (246KB) ( 427 )  
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    A mathematical model is proposed for predicting small molecule solvent diffusion coefficients in amorphous glassy polymers, based on free volume theory that is suitable for rubbery polymers, and with the consideration of the plasticization effect induced by the penetrant. Because this model uses the identical conceptual framework in which free volume theory is derived for solvent diffusion in rubbery polymers, parameters used in free volume theory remain valid for this work. Only one parameter is introduced to describe the plasticization effect, and it can be easily estimated by thermodynamic theory about the glass transition temperature depression. Therefore, no adjustable parameters appear in this expression, resulting in its usefulness in prediction. Comparison of the diffusion coefficients calculated by this new model with the present experimental data, including benzene, toluene, ethylbenzene in polystyrene (PS) and poly(methyl methacrylate) (PMMA) are performed, calculation results in this study are in good agreement with experimental data, for the correct estimation of the hole-free volume change above and below the glass transition.
    AGGLOMERATE PARTICULATE FLUIDIZATION OF PRIMARY NANO-PARTICLES
    WANG Yao;JIN Yong;WEI Fei;WU Jun
    2002, 53(4):  344-348. 
    Abstract ( 780 )   PDF (226KB) ( 247 )  
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    The fluidization characteristics of 16 nm SiO 2 powder were investigated in a small-scale transparent column. Experiments indicated that agglomerates were formed during fluidization when the gas velocity exceeded the apparent minimum fluidization velocity of the primary particles, which could be smoothly and uniformly fluidized . Surprisingly, in this case the bed expansion was fairly higher than that of Geldart-A particles, and the particulate region was rather broad. With stable,light and large agglomerates, the fluidization behavior was something like that of a liquid-solid fluidized bed.

    DYNAMIC MATHEMATICAL MODEL OF PRESSURIZED FLUIDIZED BED COMBUSTOR
    LI Zheng;PENG Zefei;HAN Zhiming;BAI Quan;NI Weidou
    2002, 53(4):  349-354. 
    Abstract ( 666 )   PDF (208KB) ( 332 )  
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    The dynamic model of a pressurized fluidized bed combustor was studied. In order to reflect the distribution of temperature along the axial direction as well as to increase the speed of model calculation, a combined discretization strategy was applied, which divided the combustor into a certain number of cells for hydrodynamic and heat transfer calculations and further grouped some neighboring cells into a smaller number of sections for mass and energy balance calculations. By dividing the dense bed into three different phases and considering the bubble behavior and gas mass transfer between the adjacent phases, the model was able to simulate the bypassing of oxygen from bottom to the freeboard as well as the difference of oxygen concentration in different phases. The dynamic model was set up based on the dynamic balance equations of solid mass, oxygen mass, carbon mass and total energy in each section. The static balance calculation results of the model were compared with the experimental data from a real 60 t·h -1 PFBC boiler and agreement was found to some extent. Finally, the fast bottom ash draining process was simulated with the model, which showed that the model indeed had the ability to describe this unique load changing operation of PFBC correctly and reflected the combustion mechanism of fluidized bed essentially.
    MASS TRANSFER CHARACTERISTICS IN COILED HOLLOW-FIBRE MEMBRANE EXTRACTION
    LIU Shunhua;LUO Guangsheng
    2002, 53(4):  355-359. 
    Abstract ( 567 )   PDF (167KB) ( 262 )  
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    Based on membrane extraction and helical tube technique, the mass transfer performance of some membrane modules with a different helically wound hollow-fibre was studied with the system of 30%TBP (in kerosene)-water and phenol as the solute. The effects of two phase flow rates, geometry of the membranes on mass transfer coefficients were investigated. The experimental results show that the helically wound hollow-fibre membrane makes much better performance in mass transfer. With an increase in the velocity of the aqueous phase in the tube, the overall mass transfer coefficients increase very quickly. The overall mass transfer coefficients have some relationship with the configuration parameters. When the pitch and inner diameter of the coiled membrane is decreased, the mass transfer coefficients will be increased. The overall mass transfer coefficients can be predicted with an equation.

    TRANSITION FROM CHURN FLOW TO ANNULAR FLOW FOR UPWARD GAS-LIQUID IN VERTICAL CONCENTRIC ANNULUS

    ZHANG Jun;JIN Youhuang;CHEN Tingkuan
    2002, 53(4):  360-363. 
    Abstract ( 703 )   PDF (139KB) ( 249 )  
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    Churn flow and annular flow are common flow patterns encountered in gas-liquid systems through conduits.In this paper,the transition from churn flow to annular flow for upward gas-liquid in vertical concentric annulus is studied and a transition model is developed by considering the structural feature of the concentric annulus and the flow characteristics for churn and annular flows in the concentric annulus.The present model is compared with the experimental data from this paper and other authors along with existing models.It is in better agreement with experimental data than existing models.

    INFLUENCE OF STRUCTURAL PARAMETERS OF CORRUGATED PLATE PACKING ON ITS PERFORMANCES
    JIA Shaoyi;SUN Yongli;ZHAO Jinduo;WU Songhai;XING Yikun
    2002, 53(4):  364-368. 
    Abstract ( 766 )   PDF (164KB) ( 268 )  
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    The influence of structural parameters of corrugated plate packing on its performance of axial mixing in liquid phase and hydrodynamic and mass transfer was investigated in a Φ 300mm ID packing tower.The results shown that the axial backmixing parameter Pe increases with increasing opening ratio and the inclination angle β and with decreasing the unit height of the packing H and that the pressure drop of packing layer Δ p/Z decreased with increasing opening ratio and unit height of the packing H and with decreasing inclination angle β and that the height of mass transfer unit H OG decreased with increasing inclination angle β and with decreasing unit height of the packing H ,and that influence of opening ratio on the height of mass transfer unit H OG had a suitable value.Through regressing experimental data,the correlative expressions of the axial backmixing parameter Pe and the pressure drop of packing layer Δ p/Z and the height of mass transfer unit H OG were obtained.The results could be of value to development and design of corrugated plate packing.
    PARTIAL SEPARATION PROPERTIES OF HUMAN EPIDERMAL GROWTH FACTOR IN GEL CHROMATOGRAPHY
    TONG Wangyu;YAO Shanjing;ZHU Ziqiang
    2002, 53(4):  369-372. 
    Abstract ( 560 )   PDF (159KB) ( 149 )  
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    Human epidermal growth factor(hEGF),a polypeptide growth factor comprising of 53 amino acid residues, has become one of research hot spots in medical field because of its various biological functions. In order to purify hEGF, the influences of flow rate, sample volume and column height on separation performance of hEGF in gel chromatography are investigated. Results indicate that there is a little influence of flow rate on distribution coefficient of hEGF and distribution coefficient of hEGF apparently increases with the increase of sample volume injected, while column height has no influence on distribution coefficient of hEGF. The standard deviation of hEGF decreases with increasing flow rate and column height,especially when flow rate is less than 6cm·h -1 and column height is lower than 8cm. It also increases with the increase of sample volume injected,especially when the sample volume injected is larger than 3ml. These results imply that the resolution will sharply decrease when flow rate and column bed height are less than 6cm·h -1 and 8cm respectively and the sample volume injected is more than 3ml under given conditions.
    REFOLDING OF DENATURED-REDUCED LYSOZYME FACILITATED BY β-CYCLODEXTRIN
    DONG Xiaoyan;SHI Jinhui;SUN Yan
    2002, 53(4):  373-377. 
    Abstract ( 586 )   PDF (201KB) ( 184 )  
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    The oxidative refolding of denatured-reduced lysozyme in the presence of cetyl trimethyl ammonium bromide (CTAB) and/or β -cyclodextrin ( β -CD) was investigated. The renaturation yield was improved in the presence of β -CD which inhibited the hydrophobic interaction between the unfolded protein molecules. However, β -CD concentration should be 3000-5000 times higher than the denatured enzyme to achieve a significant refolding effect. In contrast to β -CD, the refolding system with both CTAB and β -CD showed more favorable effect on the enzyme renaturation. With a properly enhanced guanidine hydrochloride concentration, the enzymatic activity of the denatured-reduced lysozyme could be completely regained. In addition, the optimal pH (8.5) and temperature (37℃) was established for the CTAB+ β -CD renaturation system.
    KINETICS AND PROCESS MODELS FOR DEGRADATION OF AZO DYE CARPLON RED BY LIGNIN PEROXIDASES
    ZHANG Zhaohui;XIA Liming;LIN Jianping;CEN Peilin
    2002, 53(4):  378-383. 
    Abstract ( 637 )   PDF (207KB) ( 333 )  
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    Lignin peroxidase(Lip) was produced by Phanerochaete chrysosporium fermentation and the fermentation broth was used to degrade azo dye,Carplon red.The initial reaction rates of dye degradation by Lip were experimentally measured by on-line analysis with HP8452A UV/Vis spectrometer at different concentrations of H 2O 2 and Carplon red.The experimental results showed that the initial reaction rates were inhibited by high concentration Carplon red.A mathmatical model considering both two-substrate reaction and substrate (dye) inhibition was proposed and a reaction rate equation was derived.The model simulations were in good agreement with the experimental data.In batch degradation process,automatic disappearance of H 2O 2 and Lip deactivation by H 2O 2 were observed,and the cation free radical of dye was converted into degradation products.Based on the above experimental results,a model was established to describe the Lip-catalyzed batch dye-degrading process.The results indicated that the model was able to simulate the experimental data,and the average deviation is less than 10%.
    EXERGY ANALYSIS OF TFE/NMP ABSORPTION REFRIGERATOR
    YANG Hanqiang;ZHANG Xiaodong;ZHAO Zongchang
    2002, 53(4):  384-389. 
    Abstract ( 595 )   PDF (196KB) ( 553 )  
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    TFE/NMP(2,2,2-trifluoroethanol/ N -methyl-2-pyrrolidone) is a new pair of working fluid,which is friendly to environment. A theoretical exergy analysis of a TFE/NMP absorption refrigerator based on the second law of thermodynamics is presented in order to find the link of the energy transformation process in this cycle. By analyzing influences of variation of parameters on the system’s COP and ECOP , the optimum parameters such as cycle ratio of solution, concentration of feed, and temperature of evaporator and condenser are determined. Meanwhile, the system’s COP and ECOP can be increased largely by adding the subcooler. The results obtained can be helpful to improving the system performance and make the design of the system optimum.
    ANALYSIS OF MULTIPLICITY AND TRANSIENT PATTERNS OF ISOTHERMAL CMSMPR CRYSTALLIZERS(Ⅰ) CONDITIONS FOR EXISTENCE OF MULTIPLICITIES AND APPEARANCE OF SUSTAINED OSCILLATIONS
    YIN Qiuxiang;WANG Jingkang;ZHANG Meijing
    2002, 53(4):  390-394. 
    Abstract ( 581 )   PDF (182KB) ( 128 )  
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    The possibilities of both multiplicities and sustained oscillations are explored by using the bifurcation theory for an isothermal continuous mixed suspension-mixed product removal (CMSMPR) crystallizer in which primary nucleation described by the Volmer model and secondary nucleation described by the magma dependent power law model take place simultaneously.The conditional equations for the existence of multiple steady states and the appearance of sustained oscillations are developed.The multiplicity boundary and sustained oscillation boundary, which are only dependent on the physical and kinetic properties and operational parameters of the process,are obtained by resolving these conditional equations by using the continuation technique.

    ANALYSIS OF MULTIPLICITY AND TRANSIENT PATTERNS OF ISOTHERMAL CMSMPR CRYSTALLIZERS(Ⅱ) BIFURCATION BEHAVIOR AND TRANSIENT CHARACTERISTICS
    YIN Qiuxiang;ZHANG Meijing;WANG Jingkang;XU Zhao
    2002, 53(4):  395-400. 
    Abstract ( 678 )   PDF (212KB) ( 149 )  
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    The bifurcation behavior in various parameter regions is explored for an isothermal continuous mixed suspension-mixed product removal (CMSMPR) crystallizer in which primary nucleation and secondary nucleation take place simultaneously by resolving the steady state equations with the continuation technique for nonlinear equations.The number of the steady states of the crystallizer in various parameter regions is determined and the stability of the steady states is analyzed by use of the Routh-Hurith criteria.In addition, the transient characteristics of the crystallizer in both multiplicity and sustained oscillation regions are investigated by resolving the dynamic equations with a fourth-order Runge-Kutta technique.

    MONTE CARLO SIMULATION FOR MICROPHASE SEPARATION OF MOLTEN DIBLOCK COPOLYMER CONFINED BETWEEN TWO PLATE SURFACES
    FENG Jie;LIU Honglai;HU Ying
    2002, 53(4):  401-406. 
    Abstract ( 513 )   PDF (222KB) ( 216 )  
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    Using the bond-fluctuation-model and vacancy-diffusion-algorithm,the microphase structure, segment profile and structure factor of molten symmetrical AB diblock copolymer confined between two impermeable plate surfaces are simulated by Monte Carlo method based on simple cubic lattice.It is shown that microphase is lamellar and lamellar orientation is determined by the characteristics of plates.The lamella between two neutral plates is perpendicular to plates.That between two symmetrical preferential plates or asymmetrical preferential plates is parallel to plates.If one of plates is attractive and the other is neutral, the microdomain is perpendicular lamellar structure near neutral plate and parallel lamellar structure near attractive plate.The structure factor shows that microphase structure of symmetrical system is mainly decided by the symmetry of external field.

    ANALYSIS OF EFFECT OF FOULING ON THERMODYNAMIC PERFORMANCE OF CONVECTIVE HEAT TRANSFER PROCESS THROUGH DUCT WITH CONSTANT WALL TEMPERATURE
    WU Shuangying;ZENG Danling;LI Yourong
    2002, 53(4):  407-411. 
    Abstract ( 690 )   PDF (168KB) ( 239 )  
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    Fouling is considered as one of the important factors affecting the performance of heat transfer and flow process in heat transfer equipment.The existing studies neglect the simultaneous effect of fouling on heat transfer and flow performance and have not demonstrated the effect of fouling on the variation of irreversibility loss.This paper is based on the first and second laws of thermodynamics and the effect of fouling on the thermodynamic performance of convective heat transfer process through a duct with constant wall temperature is investigated analytically.A criterion evaluating the effect of fouling on the thermodynamic performance of convective heat transfer process--the entropy generation increase rate per unit heat flux is put forward.The effect of Reynolds number (not considering fouling) and dimensionless inlet temperature difference on the entropy generation increase rate per unit heat flux is discussed.The results show that the entropy generation increase rate per unit heat flux increases with the increase of Reynolds number and dimensionless inlet temperature difference, the entropy generation per unit heat flux caused by heat transfer decreases and that caused by viscous flow increases when fouling appears and mass flow rate is constant.The criterion put forward in this paper can not only illustrate the effect of fouling on heat transfer process, but also on flow process.In addition, the entropy generation caused by conduction of fouling plays an important role in total entropy generation of heat transfer process through a duct.The research reported in this paper provides a valid way to analyze quantitatively the effect of fouling on heat transfer and flow process performance.
    PREDICTION OF ADSORPTION EQUILIBRIA FOR NONIDEAL ADSORBED SOLUTION OF BINARY LIQUID MIXTURES
    LIU Xiaoqin;YAO Huqing;SHI Jun
    2002, 53(4):  412-416. 
    Abstract ( 693 )   PDF (164KB) ( 262 )  
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    Using the thermodynamic consistency of adsorption for vapor or liquid phase together with the consideration of solution theory,surface thermodynamics and phase exchange model, the model for prediction of adsorption equilibria from binary solutions on solids with the adsorption isotherm of pure unsaturated vapors was proposed.The model only has four unknown parameters.Binary systems were tested with the proposed method.The results show that the predictive values have a good quantitative agreement with the experimental data.

    化工数据
    THERMOCHEMICAL PROPERTY PREDICTION ON BASIS OF 1 H NMR DETERMINATION FOR PETROLEUM FRACTIONS
    FANG Wenjun;XU Bin;YU Qingsen;LIN Ruisen;WANG Guoping
    2002, 53(4):  417-421. 
    Abstract ( 918 )   PDF (168KB) ( 285 )  
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    Structural parameters, such as 1 H NMR spectrum, hydrogen and carbon atom contents,for 20 petroleum fractions from two crude oils were determined by using nuclear magnetic resonance (NMR) spectroscopy and elemental analysis.The thermochemical properties,combustion enthalpy and vaporization enthalpy of these fractions were also measured.Each average molecule in the petroleum fraction was supposed to be composed of five simple groups,CH 3,CH 2,CH,ACH and C,and the group number was calculated respectively on the basis of the results of 1 H NMR determination and elemental analysis.Combustion enthalpies and vaporization enthalpies of the investigated fractions were then predicted by the group contribution methods originally for pure organic compounds in the literature.The predictive results were in reasonable agreement with the experimental data.

    LIQUID-LIQUID EQUILIBRIUM DETERMINATION AND CORRELATION OF CH3OH/H2O/H2O2/TMB/TOP QUINARY SYSTEM
    MENG Xiangkun;WANG Chunyan;XU Xien
    2002, 53(4):  422-426. 
    Abstract ( 734 )   PDF (132KB) ( 216 )  
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    In this paper,the liquid-liquid equilibrium data of methanol/H 2O/H 2O 2/TMB/TOP are determined at 40℃ and at normal pressure.The experimental data are correlated with UNIQUAC and NRTL models,and the results are satisfactory.The relative mean deviation is less than 4%, and the relative maximal deviation is less than 8%.These parameters can be used to simulate the extraction process of the integrated process of epoxidation of propylene catalyzed by titanium silicalite (TS-1) and production of H 2O 2 by anthraquinone route.

    研究简报
    APPLICATION OF ULTRASOUND DOPPLER VELOCIMETRY IN MULTIPHASE FLOW MEASUREMENT
    WANG Tiefeng;WANG Jinfu;ZHANG Huan;JIN Yong
    2002, 53(4):  427-432. 
    Abstract ( 818 )   PDF (206KB) ( 561 )  
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    This work aims to investigate the application of ultrasound Doppler velocimetry in multiphase flow.The experimental results show that in the homogeneous liquid-solid system,the amplitude of the received echo energy decreases exponentially with measurement depth,and attenuation rate increases with increase of solid holdup monotonously.A model based on the ultrasound reflection and refraction law and scatter characteristics of particles is proposed to predict the relationship between received echo energy and solid holdup.In the gas-liquid system,liquid velocity and bubble rise velocity can be directly obtained from the velocity profile by Dop 2000 when the bubble number is small,while in medium gas velocity range,FFT must be executed to calculate velocity distribution, resulting in a two-peak distribution,which in turn can be used to obtain liquid velocity and bubble velocity by further data processing.

    LIQUID-LIQUID EQUILIBRIUM FOR ETHANOL-STYRENE-WATER TERNARY SYSTEM
    YANG Yunquan;DUAN Zhengkang;LIU Wenying;TONG Gangsheng;LUO Hean
    2002, 53(4):  433-435. 
    Abstract ( 697 )   PDF (116KB) ( 340 )  
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    Liquid-liquid equilibrium data were measured for a ethanol-styrene-water ternary system at temperature of 25.00,35.00,40.00 and 50.00℃ and were correlated with UNIQUAC model.The model parameters were estimated based on a mole fraction objective function.The calculated values were in good agreement with the data measured.

    THREE PARAMETERS CHARACTERIZING PROPERTIES OF HEAT-EXCHANGERS
    YANG Weijuan;ZHOU Junhu;LIU Jianzhong;ZHOU Zhijun;HUANG Zhenyu;CEN Kefa
    2002, 53(4):  436-439. 
    Abstract ( 656 )   PDF (145KB) ( 158 )  
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    Aimming at fouling and the changes of fluid temperature and flow exist during the long use of heat-exchangers,three parameters, NTU , θ and R ,are defined to characterize the heat transfer properties of different heat-exchangers in view of the second law of thermodynamics.The studies are performed from both theory and an example of how three parameters influence heat exchange.The conclusions are derived to guide the high-efficiency operation of heat exchangers.Heat transfer decreases as NTU or θ or R decreasing.And fouling affects less the heat exchangers with bigger R than those with smaller R ,while fouling affects the heat transfer independent of θ .