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Table of Content
25 September 2005, Volume 56 Issue 9
    热力学

    New algorithm of vapor-liquid-liquid-hydrate multi-phase equilibrium flash calculation

    MA Qinglan;CHEN Guangjin;SUN Changyu;GUO Tianmin

    2005, 56(9):  1599-1605. 
    Abstract ( 833 )   PDF (406KB) ( 494 )  
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    In this work, a new algorithm for performing vapor-liquid-liquid-hydrate multi-flash calculation was developed.Patel-Teja equation of state was used in performing the vapor-liquid-liquid (V-LHC-LW) three-phase flash calculation and Chen-Guo two-step hydrate model was used for calculating the vapor-hydrate phase equilibria.This method was rather simple as it avoided the complexity of simultaneous solution of a sophisticated group of equations.The proposed algorithm was tested on gas-pure water systems, gas-aqueous solution of alcohol systems, gas-aqueous solution of salt systems and gas system containing no free water.The calculation results showed that the proposed algorithm was stable and effective.
    Influence of Marangoni effect on heated falling films
    ZHANG Feng, GENG Jiao, MA Shaoling, ZHANG Zhibing
    2005, 56(9):  1606-1611. 
    Abstract ( 756 )   PDF (781KB) ( 334 )  
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    The hydrodynamic characteristics of heated falling films flowing down a vertical flat plate were investigated with infrared thermal-camera and film-thickness meter. Temperature profiles of the film and film dimension profiles were measured by experiments.The heated falling film was remarkably influenced by the Marangoni effect induced by the variation of surface temperature and contracted in the transverse direction of the film.The impacts of the Marangoni effect on the shrinkage and thickness of film were experimentally determined.
    传递现象

    Simulation of temperature field in filling stage of injection molding using three-dimensional model

    GENG Tie;LI Dequn;ZHOU Huamin;SHAO Yujie

    2005, 56(9):  1612-1617. 
    Abstract ( 659 )   PDF (1901KB) ( 465 )  
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    The variation of the temperature of polymer would have important influence on the injection molding process.So predicting exactly the temperature field during filling is very meaningful.3D numerical analysis of temperature field in filling stage of injection molding is investigated with the FEM method.Without the use of the Hele-Shaw approximation, the three-dimensional theoretical model and numerical scheme for temperature field were established by considering the influence of convection items in three dimensions.The energy equation was discretized using the Galerkin method.In order to keep numerical stability, the upwind method was used to handle the convection item and viscous heat item.The temperature field of the non-Newtonian and nonisothermal fluid within cavities with arbitrary thickness could be pridicted with the model.A wider range of parts was possible and the prediction results were better than the 2D or 2.5D model.The validity of the model was tested through the analysis of two cavities.
    Flow and heat transfer in comby fractal microchannel network
    DONG Tao, CHEN Yunsheng, YANG Zhaochu, BI Qincheng, WU Huilong, ZHENG Guoping
    2005, 56(9):  1618-1625. 
    Abstract ( 723 )   PDF (689KB) ( 541 )  
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    Enlightened by the fractal character of natural honeycomb, a novel biomimetic comby fractal microchannel (BCFM) network was designed and fabricated by micromachining.Optimized parameters were presented by the use of the microchannel heat sinks porous medium model. Provided the channel cross-section, convection heat transfer coefficient, and temperature difference were same, the heat removal capacity of BCFM was over 5 times as that of traditional parallel microchannels.Given the total quantity of heat transfer, the pump power required in BCFM network was as low as one tenth of that in traditional parallel microchannels, neglecting the bifurcate and confluent flow effects.Experimental results of deionized water laminar convective heat transfer showed that,the BCFM network had higher mean Nusselt number and lower pressure drop than traditional parallel microchannels. The BCFM network could be used not only in electronics cooling, but also in micro structure designs, e.g., polar plate of micro PEM, micro mixer, and micro chemical reactor.
    传递现象

    Dropwise condensation heat transfer model with liquid-solid surface free energy difference effect

    LAN Zhong;MA Xuehu;ZHANG Yu;ZHOU Xingdong;CHEN Jiabin

    2005, 56(9):  1626-1632. 
    Abstract ( 840 )   PDF (485KB) ( 322 )  
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    Dropwise condensation heat transfer performance depends on not only the condensing conditions, but also the interfacial interaction between liquid and solid. Compared to the well-established Rose’s model, a new model of dropwise condensation heat transfer was proposed by considering the interfacial interaction between liquid and solid, and was established by rebuilding the space conformation of drop distribution into time conformation.The simulation results indicated that heat transfer coefficient increased with increasing surface free energy difference and decreasing contact angle hysteresis. A larger contact angle and the smaller departure drop size resulted in higher heat transfer coefficient. Different interfacial effects gave rise to different heat transfer curves. For the identical solid-liquid-vapor system, the simulation results agreed well with the present experimental data and those reported by Rose.The disagreement between experimental results in literature might be well explained with the concept of the present paper.
    3D numerical simulation of fluid flow and heat transfer in self-rotating twisted-tape-inserted tube
    ZHANG Lin, QIAN Hongwei, XUAN Yimin, YU Xiumin
    2005, 56(9):  1633-1638. 
    Abstract ( 721 )   PDF (1096KB) ( 477 )  
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    A three-dimensional fluid flow model for a self-rotating twisted-tape-inserted tube was presented.The RNG k-ε turbulent model was used to simulate the fluid flow and heat transfer in the self-rotating twisted-tape-inserted tube.The characteristics of fluid flow and heat transfer in the self-rotating twisted-tape-inserted tube were determined.Numerical simulation results showed that the fluid flow was a complex three-dimensional helix flow in the self-rotating twisted-tape-inserted tube.Axial velocity was higher in the annular area near the tube wall than that in the smooth tube; the tangential velocity in the diameter area corresponding to the width of twisted tape increased with the radius.The tangential motion in the annular area between the twisted tape and tube wall was obvious, but the tangential velocity decreased with the radius. However, the tangential motion of the fluid in the smooth tube was only stochastic, and the tangential velocity was smaller by two orders of magnitude.The radial velocity and turbulence intensity were also larger than those in the smooth tube.Due to increase of the axial velocity,tangential velocity,radial velocity and turbulence intensity, the convection heat transfer of the fluid was strengthened and the surface heat transfer coefficient for the self-rotating twisted-tape-inserted tube was larger than that of the smooth tube.In addition, numerical simulation results of the velocity field were compared with the experimental data measured by Laser Doppler Velocimeter (LDV) system.The numerical simulation results showed reasonably good agreement with the experimental data.
    传递现象

    Numerical simulation and experimental study of miniature heat pipe heat exchanger in enclosed space

    SUN Shimei;ZHANG Hong

    2005, 56(9):  1639-1643. 
    Abstract ( 626 )   PDF (1425KB) ( 605 )  
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    In recent years,miniature heat pipe heat exchanger has been used widely in machinical-electronic systems.Numerical simulation of heat pipe heat exchanger in an enclosed space was presented for the design of such a challenging device.Experimental study was made to verify numerical simulation and design,which are in fairly good agreement with experimental data.Engineering basis was provided for volume-productirity of heat pipe heat exchanger in an enclosed space.
    多相流

    Two-scale second-order moment two-phase turbulence model and simulation of gas-particle channel flows

    ZENG Zhuoxiong;ZHOU Lixing;ZHANG Jian

    2005, 56(9):  1644-1648. 
    Abstract ( 661 )   PDF (874KB) ( 291 )  
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    For simulating gas-particle flows with particle-particle collision,the second-order moment two-phase turbulence model is composed of a particle turbulence model superposed with the kinetic theory of inter-particle collision. Theoretically this is not well justified. Based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to particle-particle collision, a two-scale second-order moment two-phase turbulence model accounting for inter-particle collision was developed. The proposed model was used to simulate gas-particle channel flows. The simulation results were in agreement with the experimental results reported in references and were near to the results obtained by using the USM-Θmodel.The large-scale Reynolds stresses were found to be larger than the small-scale Reynolds stresses in each direction.

    Oil-water flow patterns and transition characteristics in horizontal pipes

    YAO Haiyuan;GONG Jing

    2005, 56(9):  1649-1653. 
    Abstract ( 740 )   PDF (716KB) ( 352 )  
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    Flow patterns and their transition characteristics for horizontal oil-water two-phase flow in a stainless steel pipe loop (25.7 mm inner diameter,30 m long)were studied.The viscosity and density of oil were 620 mPa•s and 872.17 kg•m-3 respectively at 30 ℃, 180 mPa•s and 858.68 kg•m-3 respectively at 50 ℃.Visual observation,the local sampling method and the analysis of the pressure drop signals were used jointly,and different flow patterns were defined and distinguished.A new classification for oil-water flow patterns was proposed.The flow pattern maps were obtained from the experimental data, and the factors affecting the transition mechanism of different flow regimes were discussed.In addition, some semi-theoretical criteria for the transition between different flow patterns were proposed.Especially, an accurate model was developed to predict the critical conditions for phase inversion.Comparisons of the proposed criteria with other experimental data showed reasonable agreement.
    催化、动力学与反应器

    Simulation of suspension catalytic distillation columnfor alkylation of benzene with C12 olefins

    WANG Jian;WANG Erqiang;CHEN Biaohua;LI Chengyue

    2005, 56(9):  1654-1659. 
    Abstract ( 649 )   PDF (469KB) ( 233 )  
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    A dynamic equilibrium stage model of the suspension catalytic distillation process for alkylation of benzene with C12 olefins is developed.The prediction for steady-state based on the proposed mathematical model agrees with the steady-state experimental data and simulation results well.The stationary and dynamic models developed are used to simulate the influence of the location of benzene feed stream, disturbances of benzene and mixed hydrocarbon feed flow rates upon the suspension catalytic distillation system.Only one steady-state can exist in the system for the given conditions,and the last stage in reaction section is the optimal location of benzene feed stream.The system is stable for the imposed disturbances,and its anti-disturbance ability is very strong.

    CoO/CaTiO3 Catalyst for photocatalytic decomposition of water to hydrogen——preparation method and investigation of photocatalysis mechanism

    WANG Guiyun;WANG Yanji;QIN Ya;SONG Baojun

    2005, 56(9):  1660-1665. 
    Abstract ( 742 )   PDF (927KB) ( 452 )  
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    CaTiO3 powder was synthesized by solid-state reaction of calcium nitrate with TiO(OH)2 formed by hydrolysis of tetrabutyl titanate.The effect of supported promoters on the photocatalytic activity of CaTiO3 for the decomposition of water to hydrogen was studied, and the results showed that the photocatalytic activity of CaTiO3 could be promoted by CoO, NiO and Ag, and that the effect of CoO was the best.The influence of the treatment method for the supported samples on photocatalytic activity of CaTiO3 was investigated and the samples were characterized by means of XRD, XPS and SEM.The results showed that the structure of Co-covering CoO distributing uniformly over the surface of CaTiO3 was obtained after Co(NO3)2-impregnated CaTiO3 sample underwent thermal decomposition, reduction by hydrogen at 500 ℃,and then oxidation by oxygen at 200 ℃, and the catalyst with this structure showed higher activity.The photocatalysis mechanism of CoO/CaTiO3 was discussed.

    Effcts of Fe3+ and Ce3+ doping on photocatalytic performance of TiO2 photocatalysts

    XIA Qibin;LI Zhong;XI Hongxia;ZHAO Zhenxia

    2005, 56(9):  1666-1672. 
    Abstract ( 602 )   PDF (883KB) ( 432 )  
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    TiO2 catalysts on glass fibres were prepared by the sol-gel method, and then 0.2% Fe3+ and Ce3+ were doped to modify the TiO2 photocatalysts.Experiments of the batch photocatalytic degradation of benzene were carried out, and the results indicated that Fe3+ and Ce3+ doping could improve the photocatalytic activity of the TiO2 catalysts, of which the 0.2% Fe3+/TiO2 photocatalyst was the best.XRD, SEM and XPS were used to analyze physical and chemical variation of TiO2 catalyst surfaces after Fe3+ and Ce3+ doping.The results showed that 40—60 nm size TiO2 anatase particles were deposited on glass fibre, the concentration of Ti3+was increased and the concentration of hydroxyl was decreased on the surface of photocatalysts which were doped 0.2% Fe3+ and Ce3+.Ti3+ could adsorb oxygen and react with oxygen to produce Ti4+ and O-2 simultaneously on the surface of photocatalysts.Oxidant O-2 plays an important role in the photocatalytic degradation process of benzene.

    Aerobic one-pot oxidation of 1-octanol to octanoic acid

    JI Hongbing; QIAN Yu;HE Dugui;WANG Lefu

    2005, 56(9):  1673-1678. 
    Abstract ( 748 )   PDF (509KB) ( 374 )  
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    Highly efficient heterogeneous one-pot oxidation from 1-octanol to octanoic acid using molecular oxygen as a sole oxidant with Ru-Co(OH)2-CeO2 catalyst was developed.XRD and XPS characterizations were used to analyze the catalyst structure influenced by aging temperature.Two species of crystallines including CeO2 and Co(OH)2 existing in this catalyst were evidenced. Ru was in high oxidation state of quadravalence and well dispersed. The synergism among Ru, Co and Ce components exhibited highly catalytic activity towards one-pot conversion from 1-octanol to octanoic acid under mild condition.Firstly β elimination from 1-octanol to octanal and later radical process from octanal to octanoic acid were plausible reaction mechanism.
    Numerical simulation of flow distribution uniformity in TWC and optimal design of catalyst in CNG vehicle
    ZHANG Li, YAN Yunfei, RAN Jingyu, XIU Hengxu
    2005, 56(9):  1679-1684. 
    Abstract ( 705 )   PDF (694KB) ( 411 )  
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    A new structure of three-way catalysts(TWC) with combined flow guide device was presented and the simulated results of its influence on the flow distribution uniformity were given.A new kind of catalyst adapted to compressed natural gas(CNG) vehicle was developed.The preparation, composition and processing technology of the catalyst were put introduced.The investigation showed that due to the improvement of the combined flow guide device,the catalyst composition and the processing technology, the uniformity of flow distribution in TWC could be improved by more than 5% and the life-span of TWC could be prolonged.The dosage of noble metals in TWC of CNG vehicle was greatly decreased,and higher purification efficiency for the exhaust was obtained.
    催化、动力学与反应器

    Mechanism and influence factors of scaling phenomenon in liquid-phase oxidation of toluene by air

    TANG Shengwei;ZHANG Quanzhong;LIU Fang;LIANG Bin

    2005, 56(9):  1685-1689. 
    Abstract ( 588 )   PDF (552KB) ( 268 )  
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    Liquid-phase oxidation of toluene by air is an environment friendly technology to produce benzoic acid.In SNIA benzoic acid process, two heat exchangers are used to remove the reaction heat.However, severe scaling often occurs, especially on the tube surface of the exchangers.In the present study the scale was detected to be precipitates of CoC2O4&#8226;2H2O, which was formed from the catalyst Co ion and the by-product oxalic acid.In the oxidation intermediate products of toluene, oxalic acid, maleic acid and hydroquinone were detected by HPLC.According to the research results,oxalic acid was formed through the deep oxidation of toluene or its derivates.Reaction temperature, pressure, air flow and the contents of benzene, water, benzoic acid, as well as the catalyst amount all affected scaling significantly.It was observed that the factors which inhibited the oxidation to benzoic acid enhanced scale formation.Aeration rate influenced the scaling reversely.Impurities, such as benzene or water, increased the scaling amount.Scale decreased with increasing Co content(<100 μg&#8226;g-1).Less effect of reaction pressure was observed.
    Oxidative esterification of methacrolein to methyl methacrylate
    ZHAO Wei, LI Zengxi, ZHANG Suojiang, PANG Haijian, DONG Haifeng, ZHANG Xiangping
    2005, 56(9):  1690-1693. 
    Abstract ( 855 )   PDF (410KB) ( 520 )  
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    Supported multi-metal catalyst was prepared by impregnation.A variety of factors such as reaction temperature, feedstock ratio, alkali concentration, catalyst concentration and antipolymerizer concentration were systematically investigated in terms of their effects on the oxidative esterification reaction for methyl methacrylate production from methacrolein.The experimental results showed that under the condition of temperature 333 K,methanol/methacrolein ratio 97∶1(molar ratio),NaOH concentration 0.001 g&#8226;ml-1 and catalyst concentration 0.02 g&#8226;ml-1, methacrolein conversion and methyl methacrylate selectivity were about 100% and 71.4% respectively, after 30 min reaction.
    催化、动力学与反应器

    Enhancement of catalyst activity in isopropylation of naphthalene in hydrogen atmosphere

    ZHAO Guili;TIAN Zhenghua;WANG Pei;JIA Hongmin;LI Ben

    2005, 56(9):  1694-1698. 
    Abstract ( 637 )   PDF (438KB) ( 174 )  
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    Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene (2,6-DIPN) is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite (SDHM) as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH3-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H2 atmosphere.
    Omeprazole resolution by simulated moving bed chromatography
    WEI Feng, SHEN Bo, CHEN Mingjie, ZHOU Xianbo, WU Pingdong
    2005, 56(9):  1699-1702. 
    Abstract ( 611 )   PDF (368KB) ( 320 )  
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    The enantiomers of omeprazole were resolved by simulated moving bed chromatography on the coated cellulose triphenylcarbamate chiral stationary phase using ethanol as mobile phase.The effects of columns switching time and recycling flow rate on separation were investigated.Under the experimental conditions, as the switching time was increased, the concentration, productivity and recovery of S-omeprazole were increased, while the consumption of eluent and the purity of enantiomer were decreased.Decreasing recycling flow rate could improve separation, and the highest purity of the two enantiomers was 96.4%(S) and 88.4%(R) respectively.
    分离工程

    Conceptual design of clean separation of ternary mixture of acetone-tetrahydrofuran-water

    XIAO Jian;LIU Qinglin;XIONG Jin

    2005, 56(9):  1703-1707. 
    Abstract ( 1488 )   PDF (870KB) ( 682 )  
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    Based on the thermodynamics analysis of the mixture of acetone, tetrahydrofuran (THF) and water, the conceptual design of a clean separation process for this mixture was developed. Extractive distillation was used to separate water from the other two components. Different extractive solvents were compared through simulation with Aspen plus and it was found that triethylene glycol (TEG) was a highly selective and energy saving solvent.The extracted water could be separated from extractive solvent by ordinary distillation.The simulation results from Aspen plus showed that the separation of THF and acetone could be achieved by azeotropic distillation using cyclohexane or carbon bisulfide (CS2) as azeotropic solvent according to different end requirements. When CS2 was used as azeotropic solvent, high purity THF could be obtained while accompanied by with high energy cost due to low CS2 content in the binary azeotropic mixture of CS2 and acetone.If cyclohexane was used as azeotropic solvent, a great deal of energy could be saved at the sacrifice of reduced purity THF.The separation of an azeotropic solvent and acetone could be realized through a liquid-liquid extraction process using water as extractive solvent. No waste water and other waste liquid were produced during the whole separation process thanks to the recycling of extractive solvent and azeotropic solvent.Therefore the separation process developed here could be considered as a clean separation process.
    过程系统工程

    Constrained ant colony system and its application in process optimization of butene alkylation

    HE Yijun;CHEN Dezhao

    2005, 56(9):  1708-1713. 
    Abstract ( 594 )   PDF (613KB) ( 298 )  
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    The standard ant system is suitable for the discrete optimization problem, but it lacks special mechanism for dealing with constraints.In this paper, a constrained ant colony system(CACS) for solving constraint-handling optimization problem was proposed, which was based on the biology behavior of ant colony foraging and the heuristic rules for estimating the quality of food source.The mechanism of group recruitment and mass recruitment, which were used to guide the ant colony to search the best solution in the feasible region, were embedded to the ant colony system.To illustrate the effectiveness of proposed algorithm, two benchmark functions were used, the results demonstrated better performance of CACS for achieving global optimal.Furthermore, CACS was applied to the process optimization of butene alkylation.The satisfactory result demonstrated the effectiveness of CACS.

    Simulation of industrial catalytic reforming process by developing user’s module on ASPEN PLUS platform

    HOU Weifeng;SU Hongye;HU Yongyou;CHU Jian

    2005, 56(9):  1714-1720. 
    Abstract ( 1303 )   PDF (502KB) ( 548 )  
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    The industrial catalytic reforming process is simulated by developing the seventeen lumped kinetics model as a user module on ASPEN PLUS platform.The technique of user’s module utilizes the strong databases, complete sets of modules, and flexible simulations tools of the ASPEN PLUS system and retains the characteristics of the self-developed model.Eighteen lumped components (including hydrogen) are defined for more than three hundred compounds in the flowsheet, and special property methods suitable for the petroleum system are selected for the simulation.The developed simulation software is applied to a commercial continuous catalytic reforming process successfully.The simulation results show that fair agreements between the calculated and actual operating data are obtained.
    Numerical Simulation and Performance Optimization of Carbon Dioxide Microchannel Gas Cooler

    RAO Zhenghua;LIAO Shengming

    2005, 56(9):  1721-1726. 
    Abstract ( 642 )   PDF (460KB) ( 401 )  
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    A model was developed for micro-channel gas coolers in trans-critical carbon dioxide refrigeration systems.Fluid flow and heat transfer processes in both refrigerant and air sides were analyzed with the latest physical properties database and the corresponding correlations. The model was validated by the comparison between simulation results and experimental data under various conditions.Furthermore, the influences of major parameters on gas cooler performance were analyzed and discussed.The results indicated that the exit enthalpy of gas cooler could be reduced by increasing refrigerant pressure, increasing pass number or decreasing port diameter, but with the side effects of greater input power or pressure drop.So the above parameters should be considered comprehensively in the optimal design of gas cooler.The model developed in this paper could be used for the optimal design of gas coolers.
    生物化学工程、制药、食品和天然产物加工

    Synthesis of biodiesel from waste oil by immobilized lipase

    GAO Jing;WANG Fang;TAN Tianwei;DENG Li

    2005, 56(9):  1727-1730. 
    Abstract ( 738 )   PDF (878KB) ( 694 )  
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    Immobilized lipase from Candida sp.99-125 was used for the synthesis of biodiesel from waste oil in organic solvent system. The effect of various factors on the reaction was studied, including the inhibition of short chain alcohols on enzymatic reaction, the nature of solvents, substrate concentration, water content, mode of adding methanol and so on. As can be seen from the results, the conversion rate reached 92% under the optimum conditions, and the life span of the immobilized lipase reached more than 7 batches.
    Regulation of sodium citrate on metabolic flux distribution ofinosine fermentation process
    CHEN Shuangxi, HUANG Mingzhi, CHU Ju, ZHUANG Yingping, ZHANG Siliang
    2005, 56(9):  1731-1737. 
    Abstract ( 830 )   PDF (856KB) ( 586 )  
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    Metabolic flux analysis was used to understand macroscopical characteristics of fermentation process and cellular metabolic regulation.Based on the law of mass conservation and the assumption of pseudo-steady-state for the intermediates in the metabolic pathways,the effect of sodium citrate on the fluxes distribution of inosine fermentation process was quantitatively analyzed.It was revealed that carbon overflow between EMP pathways and TCA cycle could be restrained with the medium supplemented with sodium citrate. After 24 hours, the flux of EMP pathway decreased by 33% averagely, the flux of HMP pathway increased by 76% averagely, and the flux of inosine synthesis pathway increased by 77% on average.The final inosine yield was improved from 17.44 g&#8226;L-1 to 24 g&#8226;L-1,by an increase of 37.6%.
    Relationship between site of sulfate groups in cellulose sulfate and their anticoagulation activity
    WANG Zhaomei, LI Lin, CHEN Ling, LI Bing, GUO Siyuan
    2005, 56(9):  1738-1742. 
    Abstract ( 733 )   PDF (909KB) ( 212 )  
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    Three cellulose sulfates (CS) with their sulfate groups only at C-6 position (CSC6), only at C-2position (CSC2), and at some C-6 & C-2 positions (CSC6,2) were prepared respectively by the direct sulfation method and the regioselective sulfation method. To reveal the structure-activity relationship between sulfate groups and anticoagulation activities of CS, their anticoagulation activities were investigated by measurement of coagulation time and coagulation factor activity assays. It was indicated that CSC6,2 could significantly prolong thrombin time (tTT) and inhibit the activity of coagulation factor Ⅱa, also CSC2 had a pronounced activity of prolongation of activated partial thromboplastin time (tAPTT) and inhibition of the coagulation factorⅩa. Comparatively the anticoagulation activity and the inhibition of the coagulation factors of CSC6 were weaker than those of CSC6,2 or CSC2. The site of the sulfate groups in CS influnced the flexibility and conformation of the glycan chains, resulting in the different affinity of CS and antithrombin Ⅲ (AT Ⅲ).Thus, the prolongation of tAPTT& tTT and the inhibition of Ⅱa & Ⅹa of CS was associated with the site of the sulfate groups in CS.
    生物化学工程、制药、食品和天然产物加工

    Model of multiphase transport behavior in bio-filter for waste gas treatment

    LIAO Qiang;ZHU Shouli;ZHU Xun

    2005, 56(9):  1743-1749. 
    Abstract ( 713 )   PDF (545KB) ( 251 )  
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    In the trickling bio-filter for waste gas treatment, there exists a series of complicated transport phenomena such as gas and liquid two-phase flow, pollutant transport, and biodegradation reaction in packed bed with bio-film.A multiphase mixture model was established for studying the transport behavior in the porous packed bed with multiphase flow of multi-component fluid of trickling bio-filter for gas waste treatment. The two-phase multi-component fluids were treated as a compound fluid in this model. The momentum equation and mass component equation were given for the compound fluid based on the transport theory for multiphase flow in porous medium. The source term in the mass component equation was derived from a pore-level model to reflect the relationship of the pollutant biodegrading rate with local pollutant concentration, liquid saturation, structure of packed bed, and biochemical reaction kinetics in trickling bio-filter. To take account of the effect of packed bed clogging on the purification efficiency of trickling bio-filter with smaller particles, a bio-film coverage rate was introduced into the calculation of effective mass transfer area. The purification efficiency of trickling bio-filter for low concentration toluene waste gas was predicted theoretically from the present model for packed bed with 25 mm particles or 8 mm particles in co-current flow or reflux flow, respectively.As compared with experimental results, the discrepancy between theoretically predicted values and experimental data was within ±21.9%.
    Enhanced intracellular glutathione synthesis and export capability of Candida utilis by using low pH-stress strategy
    NIE Wei, WEI Gongyuan, LI Yin, DU Guocheng, CHEN Jian
    2005, 56(9):  1750-1756. 
    Abstract ( 834 )   PDF (629KB) ( 265 )  
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    When Candida utilis WSH 02-08 was cultivated in a glucose-ammonium sulfate medium without pH control, glutathione leakage occurred when the pH of the medium decreased to 1.5. However, analysis of the cell viability indicated that the cells were not lysed. To further study the effect of low pH stress on glutathione production, pH-controlled batch cultures were conducted, where the pH was switched from 5.5 to 1.2 at 24 h and stood at 1.2 for 6 h.Nearly all intracellular glutathione leaked into the medium and the cell viability decreased dramatically, conceiving the idea that a long-term exposure of strain WSH 02-08 at low pH environment led to a complete cell lysis. A critical point (treated at pH 1.2 for 3 h) was experimentally determined, where most cells were alive but suffering a low pH stress. Low pH-stressed C. utilis cells displayed an increased intracellular glutathione synthesis and export capability, which protected cells against short-term low pH treatment. This is the first report of glutathione secretion of C. utilis at low pH. Using this knowledge, a low pH-stress strategy was developed and applied to fed-batch production of glutathione.A 197.3 mg&#8226;L-1 of glutathione was secreted into the medium.The total glucose concentration reached 737.1 mg&#8226;L-1,increasing by 24.9% and 20.0% respectively than two control cases,and the glutathione content reached 2.67 %(mass),as compared to two control cases of 2.28%(mass)and 2.11%(mass).This study demonstrated the importance of a physiology-based fermentation strategy in the production of useful compounds.
    能源和环境工程

    Elimination of arsenic from ground water by bead cellulose adsorbent loaded with Fe hydroxide

    GUO Xuejun;CHEN Fuhua

    2005, 56(9):  1757-1764. 
    Abstract ( 772 )   PDF (560KB) ( 343 )  
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    A new adsorbent, bead cellulose loaded with Fe hydroxide (β-FeOOH) was prepared and used for the removal of arsenic from groundwater.Column experiments indicated that the adsorbent had higher efficiency of eliminating both arsenite and arsenate than other adsorbents reported in literature.High bed volumes of 2200 BV and 5000 BV up to a breakthrough concentration of 10 μg&#8226;L-1 were achieved for the arsenite and arsenate removal in the studies with groundwater arsenic concentration of 500 μg&#8226;L-1 while the empty bed contact time were 4.2 min and 5.9 min respectively.While 250 μg&#8226;L-1 of arsenite and 250 μg&#8226;L-1 of arsenate were spiked together in the groundwater and the empty bed contact time was 5.0—5.2 min, the breakthrough volumes up to 50 μg&#8226;L-1 were 7000 BV,6000 BV and 6700 BV respectively for three column recycles.The adsorbent could be regenerated with 2 mol&#8226;L-1 NaOH solutions efficiently.
    Effects of feed water C/P ratio on performance of anaerobic-anoxic-oxic process
    WANG Xiaolian, WANG Shuying, PENG Yongzhen
    2005, 56(9):  1765-1770. 
    Abstract ( 971 )   PDF (698KB) ( 212 )  
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    With the deterioration of eutrophication in China, nitrogen and phosphorus removal from wastewater have caught more and more attention, while influent C/P ratio is one of the most important influence factors. To investigate the effects of feed water C/P ratio on the performance of anaerobic-anoxic-oxic process, four different feed water C/P ratios were designed, that is 55, 45, 34,23, so as to study the variations of COD, TN, PO3-4-P and sludge characteristics with the C/P ratio. The results showed that when the C/P ratio was lower than 32, P removal efficiency increased as C/P ratio increased linearly, while the C/P ratio was higher than 32, the P removal efficiency maintained at 90%~98%, and effluent P concentration was lower than 0.5 mg&#8226;L-1.In contrast, regardless of the C/P ratio, excellent COD (90%) and good total nitrogen removal (75%~84%) were maintained throughout the experiments.However, P percentage in the wasted activated sludge (WAS) increased as the C/P ratio decreased. It was also found that denitrifying P removal existed under different C/P ratios by controlling the operation, and nitrogen and phosphorus removal efficiency could be improved.
    Mechanical properties and flame retardancy of CG-ATH/LDPE/EVA
    CHANG Zhihong, GUO Fen, CHEN Jianfeng, WANG Guoquan, LI Zhengang, ZHAO Chaofan
    2005, 56(9):  1771-1776. 
    Abstract ( 754 )   PDF (3229KB) ( 367 )  
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    The performances of LDPE/EVA (low density polyethylene/ethylene vinyl acetate copolymer) multiphase polymer blend filled with different amount of nano-aluminum trihydrate (CG-ATH) was investigated in this paper.The mass amount of CG-ATH filled into LDPE/EVA composites ranged from 10% to 70%.Tests results of mechanical properties showed that the elongation at break dropped sharply and the tensile strength dropped at first and went up later. The tensile strength of the composites of CG-ATH/LDPE/EVA reached 12.5 MPa when the amount of CG-ATH got to 60%. Through analysis of SEM photos, the consistent property between CG-ATH and LDPE/EVA multiphase polymer blend can be seen. Results also showed that although CG-ATH was not consistent to the blend, nanoparticles added could strengthen the blend.Tests of flame retardancy and analysis of TG and DSC showed that the addition of CG-ATH increased decomposition temperature of the composite,from 221.6 ℃ to 267.8 ℃.At the same time coking rate and limiting oxygen index(LOI) increased.Optimum mechanical properties and flame retardancy of the composites could be obtained at the CG-ATH’s amount of 60%.
    Factors affecting performance of polyurethane-acrylate hybrid emulsion
    ZHANG Hui, SHEN Huifang, ZHANG Xinya, HUANG Hong, CHEN Huanqin
    2005, 56(9):  1777-1782. 
    Abstract ( 637 )   PDF (827KB) ( 317 )  
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    Because of the excellent properties and wide application, the water borne polyurethane emulsion modified by acrylate has become the research hot spot in coating industries.First, the water borne polyurethane prepolymer(PU) was prepared with the method of emulsion polymerization in situ, then through the free-radical emulsion polymerization, polyurethane-acrylate(PUA) hybrid emulsion was synthesized by adding initiator and methyl methacrylate(MMA).The hybrid emulsion was characterized by FT-IR, gel permeation chromatography(GPC) and Malvern particle size analyzer.Such factors as:NCO/OH ratio, the amounts of dimethylol propionic acid (DMPA) and methyl methacrylate, and triethylamine(TEA)/DMPA mole ratio, which affected the properties and appearance of the PUA emulsion were discussed.Prepared with the technology parameters 1.3—1.4 of NCO/OH ratio, about 2.6% of —COOH content, 20%—30% of MMA content, and 90%—100% of mole ratio of TEA/DMPA, the PUA emulsion showed good overall properties.
    Synthesis and swelling behavior of NVP grafted chitosan hydrogel
    YI Guobin, CUI Yingde, YANG Shaohua, KANG Zheng, CUI Yihua, GUO Jianwei
    2005, 56(9):  1783-1789. 
    Abstract ( 575 )   PDF (629KB) ( 296 )  
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    N-vinyl pyrrolidone(NVP) grafted chitosan(CHI) hydrogels were prepared.The influences of main factors such as mass ratio of NVP∶CHI, initiator content, crosslinking agent content, polymerization temperature and acetic acid concentration on the grafting ratio and swelling property of hydrogels were discussed.Grafting ratio was up to above 300% when mass ratio of NVP to CHI was about 6.The swelling behavior of the hydrogels was studied at different temperatures, pH values and NaCl concentration of swelling mediums.It was found that the swelling ratio of the hydrogels was high when pH value was about 7.Some hydrogels showed temperature sensitivity,had ultimate equilibrium swelling ratio at about 40 ℃ and the first grade phase transition was observed. NVP grafted CHI hydrogels showed anti-polyelectrolyte effect in NaCl solution.The swelling kinetics of hydrogels was investigated with the Fick model.It was suggested from the results that swelling belonged to the non-Fick model when CHI content was above 30% and it was influenced greatly by some other factors such as relaxation, contraction of hydrogel net, interaction between solute molecular and some groups on the polymer net, interaction between polymer chain,except free diffusion of water molecules while swelling belonged to the Fick model when CHI content was lower.
    Conductivity property of polyaniline synthesized by emulsion polymerization
    FU Heqing, ZHANG Xinya, HUANG Hong, SHEN Huifang, LAN Renhua, CHEN Huanqin
    2005, 56(9):  1790-1793. 
    Abstract ( 611 )   PDF (376KB) ( 648 )  
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    The transmiting electric polyaniline was synthesized by emulsion polymerization which was carried out by using dodecylbenzene sulfonic acid as emulsifier, hexadecanol as cosurfactant,hydrochloric acid and dodecylbenzene sulfonic acid as doping agent, ammonium persulfate as initiator. The influences of reaction temperature,reaction time and ratios of aniline, dodecylbenzenzsulfonic, hexadecanol, chlorhydric and ammonium persulfate on the conductivity of polyaniline were studied.The experimental results showed the optimized technologic conditions as follows: reaction temperature 7 ℃,reaction time 6 h,the mole ratios of aniline∶dodecylbenzenzsulfonic∶hexadecanol∶chlorhydric∶ammonium persulfate were 0.05∶0.028∶0.04∶0.01∶0.05.The conductivity of polyaniline was improved by using hexadecanol as co-surfactant and hydrochloric acid and dodecylbenzenzsulfonic as dopant.At the same time the conduction mechanism of polyaniline was analyzed.
    Polysiloxane/acrylates core-shell composite emulsion(Ⅰ)Effect of emulsifiers on emulsion polymerization, particle size distribution and its morphology
    MENG Yong, WENG Zhixue, SHAN Guorong, HUANG Zhiming, PAN Zuren
    2005, 56(9):  1794-1799. 
    Abstract ( 909 )   PDF (1260KB) ( 360 )  
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    The high organosilicone content polysiloxane/acrylates composite latex with core-shell structure was prepared in the semi-batch emulsion polymerization of methyl methacrylate (MMA) in the presence of polysiloxane latex as seed.The seed was polymerized by octamethylcyclotetrasiloxane (D4) and vinyl methylcyclotetrasiloxane (Vi- D4), and methyl triethoxysilane (MTES) as crosslinking reagent.The effects of the type, compounding ratio and the weight concentration of emulsifiers on the properties of the emulsion and the average particle size, its distribution, and the morphology of the obtained latex particles were studied. The particle diameter increased in the order of three anionic emulsifiers: sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDS-2) and sodium dodecyl benzenesulfonate(SDBS).With decreasing compounding ratio of SDS/OP-10, the rate of polymerization and conversion of monomer reduced and the chemical stability of latex increased, while the latex particle size and its distribution increased.Considering all-around factors of emulsion, the best compounding ratio of SDS/OP-10 was 5∶1.Furthermore, a higher concentration of emulsifiers would cause smaller particle size, narrower particle size distribution, and faster rate of polymerization and higher conversion of monomer.The particle size distribution could be narrowed by changing the mode of adding emulsifier.In order to reduce the generation of new shell polymer particles the concentration of emulsifier must be strictly controlled to keep MMA in a “starvd”state.The polymerization of shell monomer would be restricted on the “transition area” on the surface of polysiloxane seeds to form core-shell structure composite particles.
    Preparation of exfoliated polypropylene/montmorillonite nanocomposites by two-step method(Ⅱ)Melt behavior and rheological properties
    SHI Tiejun, WU Defeng, WANG Hualin, XU Nai, ZHOU Yabin
    2005, 56(9):  1800-1804. 
    Abstract ( 659 )   PDF (967KB) ( 309 )  
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    The crystallization and melt behavior of polypropylene/montmorillonite nanocomposites (PMN) were investigated with DSC and XRD.The results showed that PMN presented higher melt point but lower relative crystallinity compared with that of pure PP.Moreover, more β crystal was found in PMN due to the existence of MMT as nucleation agent.At the same time, the appearance of β crystal restrained the growth of α crystal,decreasing its dimension.The effects of different contents, temperatures and shear speeds upon the shear viscosity of PMN were studied.The results showed that the system exhibited shear-thinning non-Newtonian behavior.As the content of MMT increased, the viscosity of the system decreased apparently.The processibility of PMN became better than pure PP.
    现代化工技术

    Synthesis of 3,3′,4,4′-biphenyltetracarboxylic anhydride

    XIE Kailin;WANG Xiaozhong;DAI Liyan;CHEN Yingqi

    2005, 56(9):  1805-1808. 
    Abstract ( 765 )   PDF (504KB) ( 638 )  
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    The laboratory preparation of 3,3′,4,4′-biphenyltetracarboxylic anhydride, which is an important monomer of polyimide, was investigated.The improvement of the synthesis method was on the halogenating reaction of o-phthalic anhydride and the dehalogenation-dimerization of monosodium 4-bromo-o-phthalate.The circulation of the catalyst was discussed.The optimal reaction conditions (solvent,temperature, time, yield)were as follows, brominating: water, 75 ℃,4 h, 78%; dehalogenation-dimerization: water, 100 ℃, 3 h, 90.4%; cyclization: acetic anhydride, reflux, 2 h, 97%.High purity product was obtained with overall yield of 68.4%.
    其他

    Relationship of emulsifier content to desensitization of emulsion explosives

    WANG Yinjun;WANG Xuguang;YAN Shilong

    2005, 56(9):  1809-1815. 
    Abstract ( 816 )   PDF (1003KB) ( 264 )  
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    Desensitization of emulsion explosives was quantified by means of measuring its explosion shock waves in water, and a concept of desensitization degree was used to express the extent of desensitization which could compare and analyze the anti-pressing performance of explosives quantitatively.The relationship of Span-80 content to pressure desensitization of emulsion explosives was studied with the method.Emulsifier content showed strong influence on pressure desensitization of emulsion explosives and desensitization degree decreased with the increase of Span-80 content.While the Span-80 content reached 4%, the desensitization degree became the least.The anti-pressing performance of the explosive was the best, but the anti-pressing performance would decrease if the Span-80 content further increased.