CIESC Journal

MICROBIAL METABOLIC ENGINEERING:GATEWAY TO DEVELOP BLUEPRINTS FOR CELL FACTORIES

LI Yin;CAO Zhu’an

2004, 55(10): 1573-1580.

Abstract ( 688 )

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Metabolic engineering is an approach to understanding and utilizing metabolic processes, by which metabolic networks and gene regulatory networks can be optimized or directly modified to enhance metabolites production or synthesize novel compounds.Development of systems biology and functional genomics in post-genomic era provides significant opportunities to construct microbial cell factories for metabolic engineering.The recent development of metabolic engineering in technology and application was reviewed, based on which several key issues were addressed and future perspectives were discussed.Finally, the strategy to develop metabolic engineering in China was proposed.

ADVANCES OF DETERMINATE PARTICLE-TRAJECTORY MODEL IN SIMULATION OF FLUIDIZED BEDS

OUYANG Jie;LI Jinghai

2004, 55(10): 1581-1592.

Abstract ( 643 )

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From a macroscopic viewpoint, the solid phase in a gas-solid fluidization system behaves like some kind of fluid, thus, most numerical simulations of fluidized beds are based on the two-fluid model.This kind of model is based on the assumption that solid phase is a continuum so that it cannot be used to identify the discrete characteristics of solid phase comprehensively. With continuously increasing computer power, the determinate particle-trajectory model (DPTM) is progressing very quickly in the multiscale simulation of gas-solid two-phase flow.The DPTM treats fluid-phase as a continuum and solid phase as discrete particles so it has been used to explore the discrete characteristics of particles. Several techniques related to the application of DPTM include the model of particles motion,calculation of drag force for particles group,coupling relation between gas and solid,determination of collision between particles, and so on. In this paper, the research for particles motion, fluid motion and coupling relation between two-phase in the DPTM is outlined. For the handling of colliding particles, the hard-sphere model, soft-sphere model and direct simulation Monte Carlo method are reviewed.Moreover, the achievements in application, advantages and disadvantages, as well as the applicable system of above-mentioned models are also summarized. As a conclusion,the DPTM has been proven to be successful and is promising in the simulation of the gas-solid system. The developing direction of the DPTM is presented as a guide for further research on the gas-solid two-phase flow.

PROGRESS AND PERSPECTIVE IN APPLICATION OF BIOINFORMATICS TO ANALYSIS OF METABOLIC NETWORKS

HE Feng;MA Hongwu;ZHAO Xueming;YUAN Yingjin;ZENG Anping

2004, 55(10): 1593-1601.

Abstract ( 759 )

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One of the challenges of contemporary bioinformatics is how to make use of the large volume of data and information from genome sequencing and high-throughput genomic studies for the analysis of large-scale metabolic networks. This article first briefly reviews the reconstruction of metabolic networks from genome information and the graphic methods for the analysis of these genome-based networks. This is followed by a survey of the two most promising concepts for the analysis of network-based metabolic pathways, namely the elementary flux modes (EFMs) and the extreme pathways (EPs) and their applications that include the analysis of structure properties and functions of metabolic networks and the design and analysis of engineering strains.The challenges and possible solutions to combining the genomic information and the above mentioned pathway analysis methods for a genome-wide understanding of metabolic pathways and their regulation are discussed.

APPLICATIONS AND PROGRESS OF MOLECULAR IMPRINTING TECHNOLOGY IN SOLID PHASE EXTRACTION

LIU Yaochi, XIANG Weizhong, XU Weijian

2004, 55(10): 1602-1607.

Abstract ( 779 )

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Molecular imprinting technology (MIT) with predetermination, specific recognition and practicability is widely used in the domain of biosensor, membrane and isomer separation, antibody mimics, enzyme-mimic catalyst and solid phase extraction (SPE).SPE is a better，more simple and more convenient separation technology than liquid-liquid extraction,and has developed rapidly in recent three decades.It is a hopeful domain that uses molecularly imprinted polymers as solid phase extraction packing (MISPE).In this paper, a brief introduction is given about the origin, principle and methods of molecular imprinting technology and solid phase extraction.MISPE for the purpose of environmental sample analysis, medicine separation, pharmaceutical analysis, clinical inspection, and others is emphasized.The achievement, existent problem and trend of MISPE are also reviewed.76 references are cited.

MEASUREMENT OF VISCOSITIES AND DENSITIES OF LIQUIDS BY VIBRATING-WIRE METHOD

MA Peisheng;ZHOU Qing;YANG Changsheng;XIA Shuqian

2004, 55(10): 1608-1613.

Abstract ( 715 )

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In this paper, the structure and theory about the vibrating-wire viscometer were introduced.The viscosity and density of fluids can be measured simultaneously by this apparatus in wide ranges of temperature and pressure.The reproducibility and accuracy of this instrument were determined using n-pentane as the test fluid.At the same time, the viscosities and desities of cyclohexane (323.15—413.15 K), n-octane(313.15—393.15 K) and benzene (303.15—445.15 K) under normal pressure and 6.10 MPa,respectively,and isooctane (298.15—403.15 K), n-heptane (298.15—403.15 K) under normal pressure and 5.10 MPa,respectively,were measured.The experimental data of viscosity and density were correlated with temperature.

PARTIAL MOLAR VOLUMES OF SOLUTES AND MOLECULAR INTERACTION IN BINARY MIXED CO₂-COSOLVENT SUPERCRITICAL FLUIDS

CAO Weiliang;LI Xuan;ZHANG Jingchang

2004, 55(10): 1614-1620.

Abstract ( 639 )

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The densities of the binary mixtures of CO₂-methanol,CO₂-ethanol, CO₂-n-butyraldehyde,CO₂-i-butyraldehyde were measured at temperature ranging from 313.5 K to 323.5 K under a pressure ranging from 7 MPa to 14 MPa.The partial molar volumes of the solutes were calculated based on the relationship between the concentrations of the solutes and the densities of the mixtures.Intermolecular interaction between CO₂ and the solutes was studied based on the partial molar volume data.The partial molar volumes of the solutes were negative and the absolute value decreases with an increasing pressure and the concentration of the cosolvent.Moreover, the partial molar volumes of the solutes were related with molecule size and space structure of the cosolvent.

MEASUREMENT AND CORRELATION OF CYCLOHEXANE-5-ETHENYL-2-BICYCLO［2.2.1］HEPT-2-ENE BINARY SYSTEM VAPOR-LIQUID EQUILIBRIUM DATA

ZENG Qingrong;WANG Guiying ;WANG Guangquan

2004, 55(10): 1621-1624.

Abstract ( 574 )

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Vapor-liquid equilibrium data for binary system cyclohexane-vinylcyclohexene,cyclohexane-5-ethenyl-2-bicyclo［2.2.1］hept-2-ene,cyclohexane-tetrahydricindene were measured at 12.0 kPa with a modified Rose equilibrium still.The experimentel data were well correlated by the Wilson equation with binary parameters alone.This model would provide the basic data for the rectification design of 5-ethenyl-2-bicyclo［2.2.1］hept-2-ene system.

PERFORMANCE OF VORTEX DIODE PUMP

GUO Yanhua;JING Shan;WU Qiulin;CHEN Jing;SONG Chongli

2004, 55(10): 1625-1630.

Abstract ( 663 )

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In this paper,the experimental study on performances of vortex diode pump, including the lift height,the distribution ratio of liquid flow,the liquid conveying rate and efficiency, was conducted.The lift height was 6.7m.Experimental results were as follows: (1)The liquid height in the tank had little influence on the performance of the pump.(2)The suction pressure had little influence on the distribution ratio of liquid flow and lift height except for the efficiency and liquid conveying rate.(3) The lift height,the distribution ratio of liquid flow,the liquid conveying rate and the efficiency increased with the increase of the discharge pressure.(4) The distribution ratio of liquid flow is mainly determined by the ratio of static pressure drop around T tube.

ENHANCED FLOW BOILING HEAT TRANSFER OF HIGH SATURATION TEMPERATURE ORGANIC FLUID IN VERTICAL POROUS TUBE

YANG Dong;LI Yongxing;CHEN Tingkuan;LI Bin

2004, 55(10): 1631-1637.

Abstract ( 684 )

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In the present study the experiments on enhanced flow boiling heat transfer in a vertical tube with porous coated surface were carried out with high saturation temperature organic fluid (cumene).Heat transfer coefficients and pressure drops vs.vapor quality were measured and compared to the experimental results of a smooth tube.Boiling curves at three different mass fluxes were also obtained.The range of test parameters in the test included the fluid mass flux from 391—790kg•m^-2•s^-1, the vapor quality from 0.09—0.58 and evaporating pressure from 0.16—0.31MPa.The correlations for heat transfer coefficients and frictional pressure drops are derived, in which the effect of fluid molecular mass was introduced.The experimental results indicated that the heat transfer coefficients of the porous tube were 1.8—3.5 times those of smooth tube and the frictional pressure drops of the porous tube were 1.1—2.9 times those of smooth tube.

THREE-DIMENSIONAL NUMERICAL SIMULATION ON CONVEYING PROPERTIES OF GAS-SOLID INJECTOR UNDER PRESSURIZATION

XIONG Yuanquan;YUAN Zhulin;ZHANG Mingyao

2004, 55(10): 1638-1643.

Abstract ( 812 )

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By using three-dimensional numerical simulation technique together with the Lagrangian and Eulerian methods, a detailed numerical simulation research of an important parameter affecting the conveying characteristics of the convergent gas-solid injector was performed.In this numerical model, the interaction between the particles and gas turbulence was considered.The calculation results indicated that the axial mean speed of particles in the gas-solid injector increased as the convergent section angle was decreased.However it showed little influence on the mean speed of particles and the mixing process of gas-solid flow in the injector when the convergent section angle was less than a critical angle.In addition, the convergent section angle and the inlet velocity of driving jet also affected the static pressure distribution in the convergent gas-solid injector.

CATALYTIC PERFORMANCE OF COPRECIPITATED Fe-Mn CATALYST IN F-T SYNTHESIS

JI Yuanyuan;XIANG Hongwei;LI Yongwang;ZHONG Bing

2004, 55(10): 1644-1649.

Abstract ( 649 )

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Light olefins and liquid fuels can be synthesized over the Fe-Mn catalyst from coal-derived syngas via Fischer-Tropsch process.In this paper, the run stability and catalytic performances of an Fe-Mn commercial catalyst prepared by the common coprecipitation method were investigated in an integral fix-bed reactor to provide the reliable data for the industrial practice.Firstly, a 2000-hour stability test of the coprecipitated Fe-Mn catalyst was carried out at 553—568K,H₂/CO=1.96, 3.00MPa and 2000h^-1.It was recognized that CO conversion over the catalyst was as high as 80% even after the 2000-hour run and its deactivation velocity was lower，especially when it was run at higher temperature, which showed that the catalyst had a good extended stability and satisfactory activity.Meanwhile,the light olefins and C₅₊ selectivities were maintained at about 20% and 60%, respectively.The catalytic performances under various reaction conditions were subsequently evaluated.It was found that the light olefins and C₅₊ selectivities changed very little when the reaction conditions were controlled within a certain range, which indicated that the coprecipitated Fe-Mn catalyst had excellent flexibility for F-T run.

BASE MODIFIED PERIODIC MESOPOROUS ORGANOSILICA AND CATALYTIC PROPERTY

YUAN Xingdong;SHEN Jian;KIM Ji Man

2004, 55(10): 1650-1653.

Abstract ( 723 )

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Organic base-functionlized periodic mesoporous organosilicas(PMO) molecular sieves were synthesized by the direct co-condensation synthesis process.Powder X-ray diffractions confirmed that the structures resembled those of the mesoporous silica material.FTIR showed that the base sites existed separately on the surface of PMOs.The results of thermogravimetric analysis(TGA) showed that the base sites were still stable at temperatures higher than 300 ℃; and the ethane group in the framework was stable at temperatures below 500 ℃.These novel solid base catalysts were used for the esterifiaction of oleic acid with methanol.The conversion of oleic acid increased as the base strength and base sites number increased.Their activities changed as PMO-DN>PMO-Py>PMO-N.The XRD intensities after reaction were much higher than before reaction.It might be attributed to the fact that the base-ethanol solution could not remove all the structure-directing agent from samples.

POLYSULFONE MICROSPHERES PREPARED BY MIXING TWO EMULSION SYSTEMS AND THEIR ABSORPTION CHARACTERISTICS

WANG Yujun;XIONG Ying;CHEN Fei;LUO Guangsheng;DAI Youyuan

2004, 55(10): 1654-1657.

Abstract ( 598 )

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According to the principle of phase inversion, polysulfone micorspheres were prepared by mixing two emulsion systems.SEM photos showed that the diameter of microspheres was relatively even and the surface of microsphers was compacted.During the preparation process, the concentration of polysulfone in dimethylformamide (DMF) and the volume ratio of continuous phase (paraffin ) versus disperse phase (DMF or water) in the two emulsion systems had significant effect on the characteristics of microspheres.The polysulfone microspheres thus formed showed a good absorption both to the acid stimulant, furosemide and the alkaline stimulant, triamterene.

EFFECT OF MICELLAR PHASE ON MULTICOMPONENT CHROMATOGRAPHIC PROCESS

JIANG Yulei;LI Xi

2004, 55(10): 1658-1664.

Abstract ( 512 )

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The characteristics of multicomponent chromatography with mobile micellar phase were analyzed by the theory of coherence and the concept of multiphase chromatography.The feature of such chromatographic process was significantly affected by both the extraction of solutes by the micellar phase from the aqueous phase and the adsorption of solutes on the stationary phase.If the extraction was predominant for the adsorptive solute, the competition effect between adsorption and extraction resulted in inversion points in the chromatographic process.The sequence of solutes flowing from the chromatogram would be changed at the inversion point, and so would the entropy condition.Although the existence of inversion points increased the complexity of the chromatographic process, it provided alternative chromatographic operations.

IMPROVED TS METHOD FOR OPTIMIZATION OF CHEMICAL PROCESSES

SHI Wenjun;HE Xiaorong;CHEN Bingzhen;QIU Tong

2004, 55(10): 1665-1668.

Abstract ( 592 )

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The tabu search (TS)method is one of the modern optimization algorithms developed from local search.It is generally used in combinatorial optimization problem.The TS method performs a “guided search” which enables it to escape from local optima.The improved TS methed has introduced to search the global optimal solution to optimization problems with continuous variables.First, according to the property of the continuous variable problem, an easy function of producing adjacent state was proposed and the function of the declining search scale was improved.The effects of tabu space, search scale and initial solution on the optimal calculation were analyzed as well.Then, the example of solving heat exchangers network problem showed the efficiency of the improved tabu search method applied to continuous variables optimization problems in chemical engineering.

DISTILLATION SEPARATION SEQUENCE OPTIMIZATION SYNTHESIS BASED ON ADAPTIVE AND PARALLEL TABU SEARCH

DONG Hongguang;QIN Limin;WANG Tao;FAN Shuanshi;YAO Pingjing

2004, 55(10): 1669-1673.

Abstract ( 566 )

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Because there is an analogous structure between the distillation separation sequence and the binary tree,the distillation separation sequence can be described as a binary tree data structure, and then, by using the method of graph theory, the change mechanism of neighboring split position in binary tree is built, as a result,a kind of effective evolutional neighborhood structure has been constructed.Adaptive mechanism and parallel technology are introduced into tabu search algorithm.This means that according to memorial frequency information the tabu length and the number of candidates are adaptively adjusted, and multitask parallel technology is realized through the arrangement of the search assignment.The numeric experiment shows that the adaptive and parallel tabu search can solve successfully large-scale distillation separation sequence synthesis problem.

SELF-ASSEMBLED LAYER ON SILVER FOR PROTECTION AGAINST CORROSION

LIU Jinhong;WANG Yihong;GUO Zhirui ;GU Ning

2004, 55(10): 1674-1677.

Abstract ( 633 )

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Self-assembled monolayer of 3-mercaptopropyltrimethoxysilane(MPS) adsorbed on the surface of silver was constructed and protection ability of the monolayer against corrosion in 0.1mol•L^-1 NaOH solution was studied by polarization techniques, contact angle and Auger electron spectra(AES).Results of polarization curves showed that the most effective MPS pretreatment concentration in ethanol was 0.1mmol•L^-1 for 6h.The corrosion potential, corrosion current density, polarization resistance and efficiency were obtained.Assembly mechanism was shown by contact angle and AES.

IMPROVED PROCESS FOR HIGH ACRYLAMIDE ACCUMULATION WITH ACCLIMATED MICROORGANISM Nocardia sp.

LIU Ming, LI Chun, GAO Yi, HUANG Ye, CAO Zhu’an

2004, 55(10): 1678-1683.

Abstract ( 618 )

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To improve the acrylamide-tolerance of Nocardia sp., acrylonitrile was fed periodically into the shaking flasks containing Nocardia sp.RS cells and the culture medium.Acrylamide was accumulated gradually along with the hydration of acrylonitrile and the RS cells were acclimated to the increasing acrylamide.The growth of cells, enzymatic hydration of acrylonitrile and the screening of acrylamide-tolerance cells were coupled in the same process.The survival rate and nitrile hydratase activity of cells in the process were investigated.The acrylamide-tolerance of the RS-1 strain achieved in that process was improved significantly compared with the RS strain.The accumulation of acrylamide catalyzed by RS-1 could reach 587 g•L^-1, which is 30.6% higher than that of RS strain in shaking flasks.And a high acrylamide concentration of 535 g•L^-1 was also achieved in a bioreactor catalyzed by the strain RS-1.The concentration of acrylamide in the bioreactor was high enough to crystallize directly in 2℃.Based on the high accumulation of acrylamide, an improved process of hydration and crystallization was designed.By applying the improved process, the energy consumption in concentration can be reduced by 32.8% compared with the present process.

MODIFIED MEMBRANE CULTURE SYSTEM FOR RESEARCH ON SOLID-STATE FERMENTATION OF FILAMENTOUS FUNGI

SHI Junling; LI Yin;CHEN Jian

2004, 55(10): 1684-1689.

Abstract ( 708 )

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It is difficult to study the metabolic behavior of filamentous microorganisms in traditional solid-state fermentation systems,due to the tight integration between mycelia and medium.It is not possible either to study the kinetics of feeding and continuous strategy in this system, since the area of medium surface would change with the inflow of fresh medium.Aiming at avoiding these difficulties,a novel membrane culture system was developed.The membrane and microorganisms were transferred from one plate to another to change the medium.Another modified membrane culture system was studied by replacing agar with absorbent cotton to simplify the operation in laboratory conditions.Coniothyrium minitans was used as a model filamentous fungus to simplify the research, since the improvement of conidial production was the major aim in solid-state culture of this fungus.Production of biomass and conidia，distribution of conidia in medium, and change of pH during cultivation period were analyzed to evaluate the applicability of this novel membrane culture system.Results showed the mycelial penetration of C.minitans into the medium by using a cellulose acetate membrane with pore size of 0.45 μm, whereas the biomass production and conidial production were not affected.The conidial production was improved by 1.8-fold when the medium contents were changed during the cultivation period.The modified membrane culture system provided similar results as PDA, whereas it is more feasible and simple for the research on continuous solid-state cultivation.This is the first report on the potential of membrane cultivation system in fed-batch or continuous cultivation of C.minitans in solid-state fermentation in laboratory conditions.The studied membrane culture system has great potential in the solid-state fermentation of other filamentous microorganisms.

BIOMASS AND MICROBIAL ACTIVITY IN BACKWASHED BIOFILTER

BAI Yu;ZHANG Jie; CHEN Shufang;YAN Lilong

2004, 55(10): 1690-1695.

Abstract ( 629 )

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Biomass and microbial activity were investigated in backwashing processes of a biofilter for tertiary treatment.The microbial groups revealed a new distribution along the biofilter depth after low flow rate backwashing for a short time.Then the start-up process was accelerated by backwashing.The biomass profile and microbial activity profile,both varying with depth,can be mathematically described by quadratic equations.Using the profiles,the demand of oxidation can be calculated to determine the air flow rate in a backwashing.Combined with the difference between biofilter and rapid gravity filters,analysis of biomass and microbial activity can determine the required air flow rate in a backwashing more accurately.

FORMATION OF POLYCHLORINATED DIBENZO-p-DIOXINS AND DIBENZOFURANS FROM PENTACHLOROPHENOL ON FLY ASH SURFACE

CHEN Tong, LI Xiaodong, YAN Jianhua, HUANG Lei, LU Shengyong, GU Yueling, CEN Kefa

2004, 55(10): 1696-1701.

Abstract ( 738 )

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Pentachlorophenol (PCP) spiked into fly ash were thermally treated under different conditions in a tubular furnace.The levels and profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) produced from that were studied.PCDD/Fs existed in the gas phase mainly.The fraction of PCDDs was higher than that of PCDFs and the major homologues were HxCDD, HpCDD and OCDD.The effects of fly ash levels and oxygen content on the formation of PCDD/Fs were investigated.The levels of PCDD/Fs increased with the increase of fly ash.The levels of PCDD/Fs and I-TEQ value were lowest when the oxygen content in the gas stream was 6.7%.In addition, the mass balances of PCDD/Fs were presented.

CONNECTIVITY INDEX OF ENVIRONMENT VALENCE AND QSPR RESEARCH FOR BOILING POINTS OF SATURATED HYDROCARBON

MU Lailong;FENG Changjun

2004, 55(10): 1702-1705.

Abstract ( 582 )

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In this paper, according to the peak numbers of the nuclear magnetic resonance and the Randic embranchment degree (δ_i) of carbon atom i, the carbon atom’s environment valence gi is defined as: g_i=(t_i+δ_i)/2.The g_ireflect the characteristic of each carbon atom, and as well as the conjunction detail of the carbon atom with other carbon atoms.So, the gi could distinguish better the chemical environment of each carbon atom in the molecule than δ_i.A connectivity index of environment valence (^mS) and its athwart index (^mS′) are proposed based on the adjacency matrix and the carbon atom’s environment valence gi.Among them, the ⁰S and ⁰S′ include the characteristic and the connectivity of each carbon atom, the ¹S and ¹S′ reflect the second conjunction between carbon atoms.Based on ⁰S′ and N(the number of carbon atom), a new structural parameter——symmetry degree (N_ec), is defined as: N_ec=［(⁰S′_S/⁰S′_C)N］^2/3,and the N_ec reflect the size of the molecule as well as the symmetry of the molecule.The N_ec, ⁰S and R_n(the biggest ring’s edge numbers of cycloalkanes) of 474 saturated hydrocarbons (216 paraffins and 258 cycloalkanes) were calculated and correlated with their boiling points.The best regression equation was obtained as follow: ln(1056-T_b)=6.9480-0.1040N_ec -0.008689⁰S-0.009614R_n+0.01998R^0.5_n,n=474,R=0.9989,F=52627,S=5.63K.The model was checked up by the Jackknife’s method.It should have overall steadiness and could be used for predicting the boiling point of saturated hydrocarbons.

[HT4H]COMPUTATION METHOD OF CHEMICAL EQUILIBRIUM OF COMPLEX SYSTEM

DENG Wensheng;JIA Dongmei ;ZHANG Qingshan;LI Minli

2004, 55(10): 1706-1709.

Abstract ( 642 )

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The chaos-Monte Carlo algorithm(CMCA) was proposed for solving chemical equilibrium of complex system.By introducing random well-distributed points into the Monte Carlo algorithm, this new approach showed good convergent probability and high-speed.Equilibrium composition of some complex systems,such as methanol synthesis, ammonia oxidation, and Claus process were calculated.The results showed good agreement with Liu Xiaodi’s and Xu Jinhuo’s calculations.Compared with the gradient method, the genetic algorithm and the modified genetic algorithm,the CMCA is simple, general and insensitive to initial value.It is an efficient algorithm based on the theory of minimization of Gibbs free energy to solve chemical equilibrium of complex system.

MEASUREMENT OF VOLUMETRIC CONVECTIVE HEAT TRANSFER COEFFICIENT IN POROUS ALUMINUM

ZHANG Houlei;TAN Junjie;ZHANG Lixin

2004, 55(10): 1710-1713.

Abstract ( 679 )

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Although forced convection in porous media has been studied for many years, there are only relatively few investigations of convective heat transfer in porous metal with porosity higher than 0.9.This paper reports an experimental study on convective heat transfer and pressure drop in high porosity porous aluminum.Four typical samples with the same porosity 0.92 but different pore density (10 PPI and 20 PPI) or material (A356 Al alloy and 6101 Al alloy) were used in the test.In order to measure volumetric convective heat transfer coefficient of air flowing in the samples, a single blow mathematical model was developed and the experimental setup was built.The air frontal velocity was located in 0.6 m•s^-1 to 2.6 m•s^-1.The effects of pore density and material on the heat transfer and pressure drop characteristics were discussed.The results showed that pore density affected the heat transfer coefficient and pressure drop drastically while the effect of material (and manufacture) was quite different for different pore densities.More work is to be done on the relations between the microstructure and the macro heat transfer performance of porous aluminum.

ENHANCING OSMOTIC DEHYDRATION WITH ACOUSTIC CAVITATION

SUN Baozhi;JIANG Renqiu;HUAI Xiulan;LI Bin;LIU Dengying

2004, 55(10): 1714-1718.

Abstract ( 700 )

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An experimental study was carried out to enhance osmotic dehydration of fruits—apples using acoustic cavitation.The variation in water losses and dry matter gain rates of materials with solute concentration, cavitation intensity, the thickness of materials and treating time segment during osmotic dehydration was discussed,at the same time, the influence of different materials on mass transfer during osmotic dehydration using acoustic cavitation was investigated.The results showed that water losses rates of materials were remarkably increased during osmotic dehydration using acoustic cavitation, but dry matter gain rates increased very little.Meanwhile the physical mechanism of enhanced mass transfer during osmotic dehydration with acoustic cavitation was clarified on the basis of analyzing the experimental results.

REACTION MECHANISM AND DYNAMICS OF H₂O₂-BASED CHLORINE DIOXIDE PRODUCTION

QIAN Yu;CHEN Yun;JIANG Yanbin;JI Hongbing

2004, 55(10): 1719-1722.

Abstract ( 834 )

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To develop a cleaner production process of H₂O₂-based chlorine dioxide, this paper presents a study on reaction mechanism and dynamics of the process.It is shown that a complex H2ClO2-ClO₃exists as an intermediate in the process.A rational reaction process is proposed, which unifies several reaction mechanisms reported by different researchers in a wider range of reaction temperature.A theoretical model of the dynamics is presented, and parameters of the model are experimentally estimated and verified.

APPLIED STUDY OF HHT AND NEURAL NETWORKS ON FLOW REGIME IDENTIFICATION FOR OIL-GAS TWO-PHASE FLOW

SUN Bin;ZHANG Hongjian;YUE Weiting

2004, 55(10): 1723-1727.

Abstract ( 631 )

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For acquiring the flow regime information of two-phase flow,a flow regime identification method using the Hilbert-Huang Transform (HHT) combined with Radial Basis Function neural networks was put forward.In this study,oil-gas two-phase flow in horizontal pipe was taken as the experimental object, differential pressure signals coming from Venturi tube were handled by Hilbert-Huang Transform,and characteristic vector closely associated with the flow regime were obtained.Flow regime was identified by using Radial Basis Function neural networks.While oil flux was in the range of 4.2 to 7.0 m³•h^-1 and gas flux was 0 to 30 m³•h^-1, this method showed high identification precision for bubble flow, slug flow, churn flow and annular flow et al.The experimental study showed that this method could precisely identify the flow regime and could be used easily.

PREPARATION OF AFFINITY-BASED COLLOIDAL GAS APHRONS FOR SELECTIVE ADSORPTION AND SEPARATION OF TRYPSIN

HE Bin;LIU Yang;SUN Yan

2004, 55(10): 1728-1731.

Abstract ( 615 )

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Triton X-114, an non-ionic surfactant, was modified with the affinity ligand of trypsin,p-aminobenzamidine (PAB) and the affinity surfactant (PAB-TX) was synthesized.Then, the affinity surfactant was used to prepare affinity-based colloidal gas aphrons (CGA).The stability of the affinity CGA was investigated at different temperatures and compared with that of the CGA prepared from Triton X-114.Compared with the CGA from Triton X-114, the affinity CGA showed high selective adsorption property for trypsin.In the separation of a protein mixture,recovery yield higher than 74% were achieved for trypsin and the separation factor reached over 1.5.The results showed that the affinity CGA possessed promising selectivity for separating trypsin from a protein mixture.

HYDROGEN SULFIDE SOLID-OXIDE FUEL CELL USING PROTON-CONDUCTING ELECTROLYTES

ZHONG Li ;CHEN Jianjun;WEI Guolin;LUO Jingli ;CHUANG Karl

2004, 55(10): 1732-1735.

Abstract ( 593 )

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A brief overview of the past and present state of art in the field of H₂S solid oxide fuel cell is presented.Electrochemical performance of a proton-conducting solid oxide fuel cell having the configuration of H₂S，（MoS₂+NiS）/Li2SO₄-Al₂O₃/Pt,air was investigated.The experimental results showed that electrolyte materials like Li2SO4-Al₂O₃, and anode substances such as MoS₂+NiS showed good chemical stability under the operating conditions of a fuel cell using H2S as the fuel, and that binary metal sulfides such as MoS2+NiS as an anode catalyst was superior to a single metal sulfide of MoS2 which sublimes above 450 ℃, and better than Pt which could be detached and resulted in the degradation of anode due to the formation of PtS.The proton-conducting and cell performance was improved at elevated temperatures due to the increase of electrochemical reaction rate and the reduction of cell resistance.OCV values around 1.0 V were observed.The maximum current and power density values obtained at 600 ℃ were 20 mA•cm^-2 and 4 mW• cm^-2, and as high as 200 mA• cm^-2 and 55 mW• cm^-2 were achieved at 700 ℃, respectively.Three different anode catalysts, Pt, MoS₂+NiS and MoS₂+NiS+Ag were described.The conductance of cell increased and the cell performance was improved with Ag powder added to anode catalysts.Current density up to 250 mA• cm^-2 and power density up to 70 mW• cm^-2 were achieved with the anode catalyst MoS₂+NiS+Ag compared to those with MoS₂+NiS at 700 ℃.

TREATMENT OF Cr(Ⅲ) WASTE-WATER WITH EMULSION LIQUID MEMBRANE

YU Xiaojiao;YAO Binghua;ZHOU Xiaode

2004, 55(10): 1736-1739.

Abstract ( 585 )

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The transfer behavior of Cr(Ⅲ) through the emulsion liquid membrane system of TBP-Span80-atoleine -kerosene was studied.The effects of membrane phase component, pH value in external phase, concentration of H₂SO₄ in internal phase，ratio of emulsion-water (R_ew)and coexisting ions on the transport rate of Cr(Ⅲ) were investigated.The results showed that the transport rate of Cr(Ⅲ)could reach 99.5% under the optimun conditions of 7%TBP, 5%Span80, 4% atoleine, 84%kerosene, 1.0 mol•L^-1 H₂SO₄ in internal phase and pH 3.5 in external phase.This method was applied to the treatment of Cr(Ⅲ) waste-water, and the residual concentration of Cr(Ⅲ) could be reduced to 1.0 mg•L^-1 ,which was below the national standard of waste-water discharge.

INFLUENCE OF TEMPERATURE ON SOLVENT SELECTIVITY FOR EXTRACTIVE DISTILLATION

ZHANG Zhigang, XU Shimin, LI Xingang, ZHANG Weijiang

2004, 55(10): 1740-1742.

Abstract ( 885 )

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Extractive distillation is an important and useful technique for separating close boiling and azeotropic liquid mixtures.Solvent selectivity is the key to achieving success.In this paper, the relation of solvent selectivity versus temperature for different mixed systems(C₆H₆+C₆H₁₂+DMSO, C₆H₆+C₆H₁₂+DMF,EtOH+EA+DMF+DMSO, C₆H₆+C₆H₁₂+DMF+DMSO) was examined by the modified UNIFAC model,which is a well-tested method to select a solvent for extractive distillation.With increasing temperature,solvent selectivity was decreased.In addition, the influence of temperature on solvent selectivity was set forth for the first time by using the Clausius-Mosotti equation.

PREPARATION OF FLAT SHEET MICROPOROUS MEMBRANES FROM IPP VIA TIPS FOR MEMBRANE DISTILLATION

TANG Na;LIU Jiaqi;MA Jinghuan;WANG Hongjun

2004, 55(10): 1743-1745.

Abstract ( 581 )

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