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05 October 2014, Volume 65 Issue 10
    CIESC Journal(HUAGONG XUEBAO)Vol.65 No.10 May 2014
    2014, 65(10):  0-0. 
    Abstract ( 232 )   PDF (1506KB) ( 317 )  
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    Solubility measurement and correlation in multicomponent systems related to separation process of liquid-phase oxidation of chromite
    JIANG Chunli, ZHANG Meixi, TAN Shiyu, DONG Lichun, ZHANG Hongjing
    2014, 65(10):  3747-3752.  doi:10.3969/j.issn.0438-1157.2014.10.001
    Abstract ( 577 )   PDF (516KB) ( 267 )  
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    The solubility of Na2CrO4, NaAlO2 and Na2SiO3 in the multicomponent systems related to the manufacture of chromium compounds by liquid-phase oxidation of chromite was measured by using the equilibrium analysis method at the atmospheric pressure and temperature ranging from 353.15 K to 403.15 K, which include ternary systems NaOH-H2O-Na2CrO4, NaOH-H2O-NaAlO2 and NaOH-Na2SiO3-H2O, quaternary systems NaOH-H2O- Na2CrO4-Na2SiO3, NaOH-H2O-Na2CrO4-NaAlO2 and NaOH-NaAlO2-Na2SiO3-H2O, and quinary systems NaOH-H2O-Na2CrO4-Na2SiO3-NaAlO2. Except the Na2CrO4 solubility in ternary system NaOH-H2O-Na2CrO4, in which NaOH concentration varied from 100 g·L-1 to 800 g·L-1, the NaOH concentration was constant at 500 g·L-1. The experimental data were correlated by the Antonie equation, λ-h equation, and Apelblat equation, demonstrating that the Apelblat equation can well predict the solubility of the systems. The results show that the presence of NaAlO2 and Na2SiO3 decreases Na2CrO4 solubility, while the coexistence of NaAlO2 and Na2SiO3 has less effect than the presence of single NaAlO2 and Na2SiO3.
    Numerical simulation of GSP gasifier based on double-mixture fractions PDF model
    BI Dapeng, GUAN Qingliang, XUAN Weiwei, ZHANG Jiansheng, YUE Guangxi
    2014, 65(10):  3753-3759.  doi:10.3969/j.issn.0438-1157.2014.10.002
    Abstract ( 456 )   PDF (1273KB) ( 323 )  
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    A comprehensive three dimensional numerical model has been developed for the GSP gasifier. Based on the assumption of chemical equilibrium, two mixture fractions, ffuel and psec, are used to describe the thermochemistry of the gasifier. Probability density function (PDF) is used to describe the coupling of turbulence-chemistry. Stochastic tracking technique is selected to describe the interaction of turbulence and particle motion. The predictions are in good agreement with experimental data and literature, proving the reliability of the model. The flow field of GSP gasifier can be divided into four regions: swirling jet region, internal recirculation region, external recirculation region and plug flow region. Oxidation reactions are mainly conducted in swirling jet region and internal recirculation region. Gasification reactions dominate the other regions. The high temperature flame impinge directly on the chamber wall of the 1/3 height of the gasifier, so more consideration should be taken on the protection of the refractory at that position.
    Visualization and quantitative analysis for Marangoni convection in process of gas-liquid mass transfer
    YU Hailu, ZENG Aiwu
    2014, 65(10):  3760-3768.  doi:10.3969/j.issn.0438-1157.2014.10.003
    Abstract ( 473 )   PDF (4939KB) ( 284 )  
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    A gas-liquid mass transfer apparatus and a Schlieren system were built to visualize the Marangoni convection patterns generated in the process of CO2 desorption from ethanol in a direction perpendicular to the interface. During the desorption, uniformly-distributed and gyrate convection patterns were observed, which tend to merge and develop with time. In addition, the information such as concentration distribution and interfacial tension gradient in the mass transfer process was studied through quantitative schlieren method. The results indicate that larger interfacial tension gradient locates at the edge and center of convectional cell, drives the movement of interfacial fluid and couples with the buoyancy effect, forming the circulating flow near interface. This circulating flow leads to a concentration distribution that has higher value at the edge and lower value inside the convectional cell. This accelerates the renewal rate of interfacial fluid element so that the mass transfer is enhanced.
    LDV experiment and characteristics of fluid flow in double wavy channel
    WANG Dan, WANG Ke, WANG Yongqing, LIU Minshan
    2014, 65(10):  3769-3775.  doi:10.3969/j.issn.0438-1157.2014.10.004
    Abstract ( 297 )   PDF (1235KB) ( 246 )  
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    A new special channel named as double wavy channel is presented. Based on the method of orthogonal experiments, 9 double wavy channels with different structural parameters were designed. In certain Reynolds number range (25≤Re≤200), the characteristics of fully developed laminar flow and heat transfer for the 9 double wavy channels were considered using computational fluid dynamics technology. The fluid flow experimental set for the channel was designed and manufactured, and flow velocities of special points in the channel were measured using laser Doppler velocimeter. It is concluded that the wave amplitude of the channel has significant effect on the characteristics. The numerical simulation results are in accordance with the experimental results and the maximum relative error of the main velocity is 28.7%. The validity and accuracy of the numerical simulation are verified.
    Triboelectrification characteristics of associated minerals in coal
    GUO Jian, DONG Kezeng, HUANG Zhengliang, WANG Jingdai, YANG Yongrong, WANG Fang
    2014, 65(10):  3776-3782.  doi:10.3969/j.issn.0438-1157.2014.10.005
    Abstract ( 466 )   PDF (513KB) ( 361 )  
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    Triboelectrification system should be designed based on the understanding of triboelectrification characteristics of coal and its associated minerals. Making minerals fully charged of different polarities is the key to strengthening triboelectrification process and enhancing separation efficiency. Pneumatic triboelectrostatic experiments were performed in a copper pipe, and a Faraday cup connected with an electrometer was used to measure the charge-to-mass ratios of particles at the pipe outlet. The effects of air velocity, solid feed rate and pipe length on the specific charge of quartz, kaolinite and calcite were investigated. Quartz, kaolinite and calcite were negative charged when rubbing against the copper pipe. The specific charge of each associated mineral increased with increasing air velocity and pipe length, but decreased with increasing solid feed rate. Under the same experimental condition, calcite acquired the largest specific charge, while quartz got the smallest, and kaolinite got the second place. The work function in order was calcite>kaolinite>quartz>Cu. Based on these results, a triboelectrification model of associated mineral particles during dilute phase pneumatic conveying in the pipe was developed. The correlation coefficient calculated from predicted results and experimental data were all larger than 0.95, and the average relative errors (ARE) were all less than 10%, which indicated that the model could accurately predict the specific charge of associated minerals during dilute phase pneumatic conveying. Therefore, the model can provide guidance for triboelectrification system design.
    Vacuum flash cooling mechanism and influence of spray flow rate
    CHEN Hua, CHENG Wenlong, ZHANG Weiwei
    2014, 65(10):  3783-3788.  doi:10.3969/j.issn.0438-1157.2014.10.006
    Abstract ( 294 )   PDF (633KB) ( 283 )  
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    In consideration of flash of water film, a model to predict the heat transfer in vacuum flash cooling was presented. The flash of water film was modeled based on the film penetration theory. The model was validated by the experimental results provided in this paper, and a favorable comparison was demonstrated with a deviation below 10%. Surface temperature and heat flux were obtained numerically and experimentally, and then analyzed. The heat transfer induced by flash of water film was dominant in high heat flux flash cooling. As spray flow rate increased, cooling performance was improved, but latent heat utilization decreased. The research result would lay theoretical foundation for application of vacuum flash cooling in the aerospace thermal control system.
    Characteristics of breakup of liquid sheet of axisymmetric opposed jets
    HUANG Guofeng, LI Weifeng, TU Gongyi, WANG Fuchen
    2014, 65(10):  3789-3797.  doi:10.3969/j.issn.0438-1157.2014.10.007
    Abstract ( 315 )   PDF (11861KB) ( 211 )  
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    The breakup process of liquid sheet formed by two axisymmetric opposed jets was experimentally studied with a high-speed camera. The breakup process, the generation and propagation process of surface wave of liquid sheet were analyzed. The influences of jet diameter, nozzle separation and jet Weber number on the breakup of liquid sheet were investigated. The frequency variation of surface wave and the size distribution of sheet disintegration were quantitatively analyzed. The propagation frequency of surface wave increased with increasing We, but decreased along the radial direction. The droplet shedding frequency of sheet edge increased with increasing We. At We>1000, a large number of droplet dots appeared at surface of liquid sheet, which promoted the breakup of liquid sheet. The non-dimensional drop size disintegrated from liquid sheet was mainly in the range of 0-1.
    Equal distribution of gas-liquid two-phase flow based on critical flow theory
    LIANG Fachun, YANG Guiyun, WANG Jinlong, YU Hao
    2014, 65(10):  3798-3804.  doi:10.3969/j.issn.0438-1157.2014.10.008
    Abstract ( 436 )   PDF (945KB) ( 372 )  
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    A novel distributor consisting of a swirl vane, nozzles and fluid splitting rooms was proposed to distribute gas-liquid two-phase flow evenly. The swirl van was used to change upstream flow patterns into annular flow with uniform film thickness to make sure all the nozzles have same inlet condition and the nozzles were used to accelerate the gas-liquid mixture to achieve critical flow. In order to investigate the distributor behavior under different extraction ratios, a 2-nozzle and a 4-nozzle distributor were designed. A numerical model was developed to simulate the gas and liquid velocity vector distribution in the distributor. The simulation results showed that all the nozzles had similar flow behavior if their outlet pressures were equal. Experiments were conducted in an air-water two-phase flow loop, with the distributor horizontally installed. Superficial gas velocity varied from 5.0 m·s-1 to 25.0 m·s-1, liquid superficial velocity was in the range of 0.012-0.14 m·s-1. The flow patterns observed during the tests included wavy flow, annular flow and slug flow. It was found that gas and liquid splitting ratio was determined by the number of the nozzles and was independent of flow patterns, gas and liquid superficial velocity and resistance characteristic of the downstream pipeline. The splitting ratios of the 2-nozzle and 4-nozzle distributors were 0.5 and 0.25 respectively.
    Migration behavior of bubble cluster emerging from micro-orifice with liquid cross flow in mini-channel
    ZHU Xun, XIE Jian, WANG Hong, LIAO Qiang, DING Yudong, FENG Hao
    2014, 65(10):  3805-3810.  doi:10.3969/j.issn.0438-1157.2014.10.009
    Abstract ( 346 )   PDF (4570KB) ( 275 )  
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    Visualization experiments were performed on migration behavior of bubble cluster emerging from a micro-orifice with liquid cross flow in a mini rectangular channel. Based on the self-developed image processing method, the influences of liquid flow rate and inclination angle of the channel on the size, velocity and trajectory of bubble cluster were discussed. Meanwhile, micro-bubbles accumulation at the top wall of the channel was observed and analyzed under different operating conditions. The bubbles size as well as the angle between bubble trajectory and channel bottom wall decreased with increasing liquid flow rate and inclination angle of the channel. Furthermore, the location and number of the micro-bubbles accumulated at the top wall were distinctly affected by liquid flow rate and channel inclination angle.
    Shell-side heat transfer and pressure drop of shell-and-tube heat exchanger with trefoil-hole baffles
    GUO Zhen, LANG Hongfang, ZHOU Guoyan, ZHU Lingyun, YANG Jinchun, ZHU Hui, ZHU Dongsheng
    2014, 65(10):  3811-3819.  doi:10.3969/j.issn.0438-1157.2014.10.010
    Abstract ( 299 )   PDF (596KB) ( 195 )  
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    Shell-and-tube heat exchanger with trefoil-hole baffles (STHX-TH) is a new type of longitudinal-flow heat exchanger which is widely used in nuclear industry due to its higher heat transfer efficiency, lower pressure, superior anti-vibration performance and many other advantages. In order to analyze the thermal-hydraulic performance of STHX-TH, an experimental test platform was established. Then four STHXs-TH with different baffle spaces were tested. The experimental data were reliable and accurate. Heat transfer coefficient and pressure drop decreased linearly with increasing Reynolds number in double logarithmic coordinates. Heat transfer coefficient and pressure drop decreased with increasing baffle space at the same Reynolds number. With the same mass flow, pressure gradient decreased with increasing baffle space. In order to comparatively understand the shell-side heat transfer and pressure drop performance of STHX-TH, a shell-and-tube heat exchanger with segmental baffles (STHX-SB) with similar geometric parameters with STHX-TH (No.2) was designed. Shell-side heat transfer coefficient and pressure drop of STHX-SB were calculated with the Bell-Delaware method, and compared with those of STHX-TH. The comparative study showed that convective heat transfer coefficient of STHX-TH was 1.25 times of that of STHX-SB, pressure drop of STHX-TH was 0.77 time of that of STHX-SB, and Nusps of STHX-TH was 1.62 times of that of STHX-SB.
    Measurement of gas/solid two-phase plug flow velocity based on modified cross-correlation method
    XUE Qian, WANG Huaxiang, MA Min, CUI Ziqiang
    2014, 65(10):  3820-3828.  doi:10.3969/j.issn.0438-1157.2014.10.011
    Abstract ( 351 )   PDF (9468KB) ( 419 )  
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    In the application of twin-plane electrical capacitance tomography (ECT) system to velocity measurement of plug flow in pneumatic conveying process, the dynamic lag correlation exponent was used to detect the average value abrupt changes of capacitance, and the detected abrupt change-points were used to determine the time windows for selecting proper upstream and downstream signals. The selected signals were thereafter mapped into binary images, which were then processed with mathematical morphology closed operation. Finally, the velocity of plug flow was estimated by implementing two dimensional cross correlation between the processed images. Experimental results demonstrated the effectiveness of the proposed method. Compared to the traditional cross-correlation method, the modified method could extract signals containing obvious fluctuations effectively, and improve the robustness of the cross correlation method by using two dimensional image correlation, enhancing the reliability of online measurement of two-phase flow using ECT.
    Heat transfer characteristics of high temperature heat pipe with triangular grooved wick under variable heat fluxes
    SHEN Yan, ZHANG Hong, XU Hui, YU Ping
    2014, 65(10):  3829-3837.  doi:10.3969/j.issn.0438-1157.2014.10.012
    Abstract ( 288 )   PDF (5218KB) ( 283 )  
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    Thermal performance of high temperature heat pipe with triangular grooved wick under variable heat fluxes has been investigated experimentally, and temperature, thermal resistance and response time have been analyzed by considering the periods and amplitudes of cyclical input power and inclination angles of heat pipe. The results show that: at start-up stage, in this experiment there is no evident difference in stable temperature and time under constant and variable power heating with the same average power. There are greater temperature fluctuations of the heat pipe with longer period or larger amplitude of the variable power. Triangular grooved heat pipe runs stably at variable heat fluxes, and can withstand harsh working conditions of 3000 W (760-3800 W) power changing in 6 min. This heat pipe has better temperature uniformity with 0° than with 45° inclination angle under variable heat fluxes. High temperature heat pipe with triangular grooved wick has good thermal response and thermal buffer under variable heat conditions, so it can further improve the system reliability.
    Fluid flow in rectangular helical channels with vortex generator
    ZHANG Li, LI Jiaqi, ZHANG Chunmei, WANG Cuihua, WU Jianhua
    2014, 65(10):  3838-3845.  doi:10.3969/j.issn.0438-1157.2014.10.013
    Abstract ( 394 )   PDF (1752KB) ( 271 )  
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    The flow field of rectangular helical channel with triangle winglet pair vortex generator was measured experimentally. The curvature of the helical channel was 0.05. The experimental data are in good agreement with the calculated data. The evolution of vorticity in the helical channel and the influence of Reynolds number and the curvature on the effective influence distance of vortex generator were investigated by numerical method. The results show that, two extra vortices in common-flow-down type emerge near the inner wall in the rectangular cross section of the helical channel with triangle winglet pair vortex generator. The values of extra vorticity are 2.0-2.8 times those of the original vorticity. The effective influence distance of the vortex generator increases with the decrease of curvature and the increase of Reynolds number. It can reach 79 times of the height of the vortex generator with the curvature of 0.05, attack angle of 10° and Reynolds number of 5370.
    Effect of particle morphology and concentration on density and viscosity of graphite nanolubricant
    LOU Jiangfeng, ZHANG Hua, WANG Ruixiang, LI Meng
    2014, 65(10):  3846-3851.  doi:10.3969/j.issn.0438-1157.2014.10.014
    Abstract ( 644 )   PDF (2995KB) ( 462 )  
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    Naphthenic base nanolubricants with good stability were prepared by modifying nano graphite in two forms with silane coupling agent KH570. An oscillating densitometer and a rotary viscometer were used to test the density and viscosity of graphite nanolubricants with mass fraction of 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, and 2% in a temperature range from 288 K to 343 K. The results show that the density and viscosity of graphite nanolubricants increase with the increase of nanoparticle mass fraction. The densities of nanolubricants adding plate-shape graphite are higher than those with spherical graphite at the same mass fraction, while the viscosity shows opposite trend. The viscosity increases obviously at the temperature higher than 313 K with spherical graphite added. Correlations for the density and viscosity are developed as a function of nanoparticle concentration, particle size and shape. The correlation for density agrees well with experimental results, with 90% of the viscosities predicted within ±5% deviation from the measurement.
    Heat transfer performance of pulsating heat pipe with ethanol-based binary mixtures
    CUI Xiaoyu, DUAN Weiwei, QIAO Tieliang, ZHU Yue
    2014, 65(10):  3852-3860.  doi:10.3969/j.issn.0438-1157.2014.10.015
    Abstract ( 326 )   PDF (794KB) ( 185 )  
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    The thermal resistance characteristics of ethanol-based binary mixture pulsating heat pipe was studied experimentally. The working fluids were ethanol mixed with water, acetone and methanol separately. Mixed ratio of volume was 2:1 and 4:1, heat power was from 10 W to 100 W, and filling ratio was 45%, 55%, 62%, 70% and 90%. Compared with the pure ethanol pulsating heat pipe at 45% filling ratio, mixed water with ethanol could delay the dry-out, and the thermal resistance of ethanol-water pulsating heat pipe was lower than that of pure water and ethanol. At 55% filling ratio, the thermal resistance of ethanol-acetone pulsating heat pipe is also lower, while at filling ratios of 62%, 70% and 90%, the thermal resistance of the binary mixture pulsating heat pipes was slightly higher than that of pure working fluids. The effect of the mixture on pulsating heat pipes is mainly related with the mixture properties, forces and momentum interchange among molecules, vapor-liquid phase equilibrium and phase change characteristics, and mass transfer resistance.
    Numerical simulation of topological chaos by Pseudo-Anosov map
    XU Baiping, FENG Yanhong, CHENG Jinwei, YU Huiwen, HE Liang
    2014, 65(10):  3861-3871.  doi:10.3969/j.issn.0438-1157.2014.10.016
    Abstract ( 308 )   PDF (2951KB) ( 228 )  
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    Numerical investigation was conducted to study the mixing behavior of Stokes flows in a rectangular cavity stirred by alternating motion of three square rods. The square loops of rod moved in two different ways that a Pseudo-Anosov map could be built in the flow domain in the augmented phase space. The finite volume method was used to solve the flow field with the periodic boundary conditions of the rod motion being imposed by the mesh supposition technique. The flow domain was meshed by staggered grids and the discretization schemes for control equations were accurate to the second-order resulting from the use of central differencing. Fluid particle tracking was conducted by a fourth-order Runge-Kutta scheme. The Poincaré section was obtained to reveal the size of the domain in which the Pseudo-Anosov map almost covered the whole cavity region except for four corner zones. The evolution patterns of tracers from different initial positions were computed to characterize the mixing process.Tracer interface stretches experienced exponential increases and had the larger power index than that predicted by the Pseudo-Anosov(pA)map matrix,which was due to the local secondary folding caused by the details of flow field, such as shapes of rods , rod trajectories and so on.
    Simulation of droplet deformation in uniform electric field with dissipative particle dynamics approach
    ZHANG Jun, HE Hongzhou, HUANG Guanxing
    2014, 65(10):  3872-3877.  doi:10.3969/j.issn.0438-1157.2014.10.017
    Abstract ( 378 )   PDF (1461KB) ( 269 )  
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    Based on DPD method, a particle mechanical model of the droplet in immiscible liquid in a uniform electric field was developed and the drop deformation process was simulated. There was better consistency in drop shape between simulation and experiment, and deviation was observed only in the case of large deformation. The simulated results also showed that at lower electric field strength drop deformation did not grow up with time, but was in an oscillation state. With increasing electric field strength, oscillation amplitude of droplet deformation increased while oscillation frequency decreased. When field strength increased to a specific value, oscillation could not be maintained and drop deformation sharply increased with time, leading to droplet breakup. The higher the field strength, the shorter the time required for drop breakup.
    A new method for measuring moisture distribution in fluidized bed
    ZHOU Yunlong, YANG Ning
    2014, 65(10):  3878-3883.  doi:10.3969/j.issn.0438-1157.2014.10.018
    Abstract ( 431 )   PDF (948KB) ( 240 )  
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    Mainly three groups exist in the fluidized bed: macro-agglomerates, micro-agglomerates, and free-particles. Agglomerates were generated by using TEB nozzles. Macro-agglomerates were distributed at the bottom of the fluidized bed, while micro-agglomerates and free-particles were uniformly distributed in the fluidized bed. The conductance signals measured by the self-developed multi-channel conductance electrical circuit experimental device showed linear relationship with moisture content inside the fluidized bed. Conductance signal was recovered under the influence of agglomerates breakup by continuous fluidization, so that measurement of moisture distribution could be implemented. Measurement of moisture distribution with TEB atomization nozzle gas liquid ratio in the range of 0-4% indicated that with the increase of gas liquid ratio, the moisture content in the micro-agglomerates and free-particles increased, while the moisture content in the macro-agglomerates decreased. But even when gas liquid ratio increased to 4%, most of the moisture content still existed in the macro-agglomerates.
    Analysis of experiments for steam condensation in presence of non-condensable gases with moderate wall subcooling
    SU Jiqiang, SUN Zhongning, GAO Li
    2014, 65(10):  3884-3890.  doi:10.3969/j.issn.0438-1157.2014.10.019
    Abstract ( 371 )   PDF (675KB) ( 305 )  
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    An experimental investigation was conducted to evaluate the steam heat removal capacity in the presence of non-condensable gases (e.g. air, helium) over a vertical tube external surface under moderate wall subcooling. Under steam/air condition, condensation heat transfer coefficients were obtained under wall subcooling ranging from 13℃ to 25℃, total pressure ranging from 0.4 MPa to 0.6 MPa and air mass fraction ranging from 0.07 to 0.52. The experiments for the influence of wall subcooling on steam condensation heat transfer with a fixed pressure and air mass fraction were made. Under the same pressure with the same non-condensable gases mass fraction, the effect of wall subcooling on condensation heat transfer coefficient with non-condensable gases was negative. An empirical correlation for heat transfer coefficient was developed, covering all data points within 15%. Under steam/air/helium (simulating hydrogen) condition, the effect of helium mole fraction in non-condensable gases on heat transfer coefficient was investigated under wall subcooling ranging from 18℃ to 27℃, total pressure ranging from 0.53 MPa to 0.6 MPa, steam mass fraction ranging from 0.6 to 0.92 and helium mole fraction in non-condensable gases 0.3. The condensation heat transfer coefficients obtained from steam/air/helium condition were lower than those obtained from steam/air case. Helium stratification was not found under the experimental conditions. With the same non-condensable gases mass fraction, presence of helium lowered condensation heat transfer coefficient by around 20%.
    Preparation of Pt nanowires as cathode catalyst for PEMFC and its application in stack
    CHANG Fengrui, HUANG Jianbiao, MA Jianxin, YANG Daijun, LI Bing, YAN Zeyu, GU Rongxin
    2014, 65(10):  3891-3898.  doi:10.3969/j.issn.0438-1157.2014.10.020
    Abstract ( 310 )   PDF (1797KB) ( 478 )  
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    Carbon supported platinum nanowires (Pt NWs/C), acting as cathode catalyst for proton exchange membrane fuel cell (PEMFC), were synthesized by reducing H2PtCl6 with HCOOH at room temperature without assistance of template. The catalyst microstructure and morphology were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Pt NWs/C had an average cross-sectional diameter of (4.0±0.2) nm and a length of 15-25 nm. Good electrocatalytic performance and oxygen reduction reaction (ORR) of the as-prepared catalyst was characterized by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). Two membrane electrode assemblies (MEAs) were fabricated, with Pt NWs/C and Pt/C as cathode catalyst respectively, and tested for comparison. The maximum power densities of Pt NWs/C and Pt/C, respectively were 705.6 mW·cm-2 and 674.4 mW·cm-2. Afterwards, an 18-cell stack with Pt NWs/C as cathode catalyst and a 20-cell stack with Pt/C as cathode catalyst were built for testing. Maximum power densities were 409.2 mW·cm-2 and 702.7 mW·cm-2, and coefficients of variation (Cv) of individual cell were 16.1% and 4.36% at the maximum power density, respectively. Data analysis indicated that Pt NWs/C for the cathode in a MEA exhibited good catalytic activity at a scale-up level, however, as compared with the commercial Pt/C catalyst, CV performance and uniformity should be improved. This work not only sheds light on the scale-up possibility of Pt NWs/C catalyst, but also provides a possibility for further durability test before its application in a fuel cell vehicle.
    Skeletal reaction mechanism for n-butane auto-ignition
    YU Yawei, ZHONG Beijing
    2014, 65(10):  3899-3905.  doi:10.3969/j.issn.0438-1157.2014.10.021
    Abstract ( 421 )   PDF (581KB) ( 300 )  
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    A reduced chemical kinetic mechanism for oxidation of n-butane was built through reaction rate analysis. The mechanism consisted of 80 species and 378 reactions and emphasized ignition progress. The reduced mechanism was used to simulate the consumption of fuel and oxygen, distribution of temperature and main products at pressure of 1 MPa, stoichiometric ratio of 1, temperature of 700 K and showed good agreement on ignition delay times with the detailed one in a wide range of pressure (0.1, 1, 2, 3 MPa), stoichiometric ratio (0.5, 1, 2) and temperature (650-1450 K), which reflected the accuracy of the reduced mechanism.
    Langmuir-Hinshelwood kinetic model of high temperature coal char gasification reaction
    REN Yizhou, WANG Yifei, ZHU Longchu, JIN Weilong, WANG Fuchen, YU Guangsuo
    2014, 65(10):  3906-3915.  doi:10.3969/j.issn.0438-1157.2014.10.022
    Abstract ( 529 )   PDF (701KB) ( 564 )  
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    When the Langmuir-Hinshelwood (L-H) kinetic model based on the theory of adsorption and desorption is used to describe the gasification reaction of coal char in the mixtures of H2O and CO2, there exist two controversial assumptions of separate active sites and common active sites. The gasification reaction characteristics of the Inner Mongolia coal char (NMJ) in the mixtures of H2O and CO2 were investigated using a tubular furnace experimental system at various reactant gas partial pressures and temperatures. The gasification reaction mechanisms of NMJ in the mixtures of H2O and CO2 were also investigated. The activation energies of NMJ-H2O and NMJ-CO2 were 214.78 kJ·mol-1 and 145.96 kJ·mol-1, respectively. H2 and CO had obvious inhibition effects on the reaction of NMJ-H2O and NMJ-CO2, and the inhibition effects of CO increased with the decrease of reaction temperature. The reaction rate curves calculated by the L-H kinetic model fitted the experimental results very well. For the gasification reaction of NMJ in the mixtures of H2O and CO2, the L-H model based on the common active sites assumption fitted the experimental results very well under atmospheric pressure, indicating that common active sites assumption was more applicable to the gasification mechanisms of NMJ in the mixtures of H2O and CO2.
    Effect of citric acid and phosphorus on properties and hydrodenitrogenation performance of MoW/Ni/Al2O3 catalysts
    LUO Yi, ZHOU Yasong, WEI Qiang, HAN Lu, LIU Xiao, ZHANG Chao
    2014, 65(10):  3916-3923.  doi:10.3969/j.issn.0438-1157.2014.10.023
    Abstract ( 405 )   PDF (6109KB) ( 646 )  
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    The trimetallic catalysts were prepared by the iso-volume impregnation method using nickel-molybdenum-tungsten as active metals and γ-Al2O3 as support. The properties of the catalysts modified by phosphorus, citric acid and phosphorus in cooperation with citric acid, as well as the catalytic performance of hydrodenitrogenation and denitrogenation selectivity were examined. The catalysts were characterized with NH3-TPD, Py-IR, H2-TPR, XPS and HRTEM. The results indicated that on the surface of the catalyst modified by phosphorus the amount of weak acid was increased. Also phosphorus promoted the sulfidation of active metals and improved the rate of removal of basic nitrogen and non-basic nitrogen. But phosphorus resulted in the increase of the stacked layers and decreased the dispersion of active metals. Citric acid added in the catalysts could lower the sulfuration temperature of the active metallic oxide, and improve the hydrogenation performance of catalysts; but it had no effect on hydrogenolysis activity, and focused on the removal of non-basic nitrogen. Phosphorus in cooperation with citric acid could not only improve the hydrogenolysis activity of catalysts, but also improve the hydrogenation performance of catalysts. As a result the rate of removal of basic nitrogen and non-basic nitrogen of the catalyst modified by phosphorus in cooperation with citric acid for coker gas oil was remarkably promoted, reaching 80.1% and 54.9% respectively.
    Preparation of CaO/HMCM-22 zeolite catalyst with acid-base bifunction with ultrasonic assistance
    WANG Junge, LIANG Jinhua, SUN Shoufei, ZHANG Wenfei, REN Xiaoqian, JIANG Min
    2014, 65(10):  3924-3930.  doi:10.3969/j.issn.0438-1157.2014.10.024
    Abstract ( 359 )   PDF (1940KB) ( 178 )  
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    CaO/HMCM-22 zeolite catalysts were prepared by ultrasonic impregnation and characterized by XRD, N2 physical adsorption-desorption, SEM, FT-IR, NH3-TPD and CO2-TPD. The structure of MCM-22 zeolite still remained after CaO modification with ultrasonic assistance. Ultrasonic cavitation could reduce the agglomeration between particles, improve the dispersion of CaO on the surface of zeolite and increase the accessible catalytic active sites. By increasing CaO loading, the strength and content of base increased, while the strength of strong acid decreased significantly and the amount of weak acidic sites increased slightly. Knoevenagel condensation reactions were conducted over the synthesized catalysts. The strategy developed here showed excellent catalytic performance for this reaction compared with the conventional impregnation method and the conversion of benzaldehyde reached 88.3% under optimal ultrasonic irradiation within 2 h reaction. The catalytic performance of CaO/HMCM-22 was better than that of HMCM-22 and CaO/NaMCM-22, resulting in good catalytic activity for Knoevenagel condensation reactions and obvious acid-base synergetic effects. The reusability of the synthesized catalysts with ultrasonic assistance was also investigated. Obvious improvment was achieved and conversion of benzaldehyde was above 65% after being reused 5 times.
    Separation and purification of anti-HER2 monoclonal antibody with hydrophobic charge-induction chromatography
    LI Jing, LIN Dongqiang, TONG Hongfei, YAO Shanjing, YE Shuaidong, CUI Jiayou
    2014, 65(10):  3931-3937.  doi:10.3969/j.issn.0438-1157.2014.10.025
    Abstract ( 304 )   PDF (3480KB) ( 271 )  
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    Hydrophobic charge-induction chromatography (HCIC) is a new technology for biomolecule separation. In the present work HCIC was used to separate monoclonal antibody (mAb) anti-HER2 from Chinese Hamster ovary (CHO) cell culture broth with typical HCIC resin, MEP HyperCel. The stability of anti-HER2 mAb in cell culture broth was investigated firstly, and the adsorption of anti-HER2 mAb onto MEP HyperCel at different pH was compared. The adsorption capacities were high at the range of pH 6-9, but decreased significantly under acidic condition. The dynamic binding capacity of anti-HER2 mAb was determined with a packed bed, and the loading and elution conditions were optimized. The suitable separation conditions were obtained, and the purity of mAb could reach 94.6% with the yield of 0.1 mg·(ml broth)-1. It is feasible to separate mAb from mammalian cell culture broth with HCIC.
    Separation of cytidine triphosphate from Saccharomyces cerevisiae broth by anion exchange poly(2-hydroxyethyl methacrylate) composite cryogel embedded with SiO2 nanoparticles
    LIU Jie, SHEN Shaochuan, CHEN Ping, XU Linhong, YUN Junxian, YAO Kejian
    2014, 65(10):  3938-3945.  doi:10.3969/j.issn.0438-1157.2014.10.026
    Abstract ( 404 )   PDF (2432KB) ( 288 )  
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    An anion exchange poly(2-hydroxyethyl methacrylate) composite cryogel embedded with SiO2 nanoparticles was prepared by cryo-polymerization followed by graft polymerization with monomer N,N-dimethylaminoethyl methacrylate. This cryogel was used to isolate cytidine triphosphate from Saccharomyces cerevisiae transformation broth. Chromatographic separation was performed with 0.01 mol·L-1 HCl as running buffer together with 0.02 mol·L-1 and 0.1 mol·L-1 NaCl solutions (prepared in running buffer) as two-step elution liquids. Cytidine triphosphate purity was analyzed by high performance liquid chromatography. Cytidine triphosphate with high purity of 97.2% and recovery of 82.5% was obtained. Compared with other conventional methods, the present separation process was simple and effective, and could be used in separation of nucleotides from microbial fermentation or transformation feedstocks.
    Adsorptive separation of 1,1,1,2-tetrafluoroethane/1,1-difluoro-2-chloroethylene over ion-exchanged Y zeolites
    ZHANG Chuang, ZHANG Bo, WEI Mingquan
    2014, 65(10):  3946-3952.  doi:10.3969/j.issn.0438-1157.2014.10.027
    Abstract ( 479 )   PDF (601KB) ( 249 )  
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    Using CaCl2, La(NO3)3 and Ce(NO3) 3 solutions, NaY was ion-exchanged to prepare CaY, LaY and CeY zeolites. Adsorptive removal of trace amount of 1,1-difluoro-2-chloroethylene (HCFC-1122) from 1,1,1,2-tetrafluoroethane product over NaY, CaY, LaY, and CeY zeolites were investigated. The structure and surface properties of fresh and regenerated adsorbents were characterized by X-ray diffraction, pyridine infrared spectra techniques and temperature programmed desorption of ammonia. Results show that the residual ratio of HCFC-1122 impurity in the eluate can be decreased to 1.0% over CaY,LaY and CeY zeolites via the formation of p-adsorption complexes between HCFC-1122 and Brønsted acid sites. The increase of intensity of Brønsted acid favors the formation of p-adsorption complexes, consequently decreasing adsorption temperature for complete removal of HCFC-1122 (CeY < LaY < CaY). Breakthrough adsorption capacity of HCFC-1122 at 220℃ increases in the order of CaY < LaY < CeY, since lower density of strong Brønsted and weak Lewis acid sites are favorable to lower degree polymerization initiated by p-adsorption complexes. The thermal regeneration of adsorbents is unsatisfactory, attributed to hardly removal of contaminant on the acid sites of saturated adsorbents during the thermal regeneration process.
    A new modified linear driving force model applied to activated carbon adsorption
    WANG Haihong, LIU Yingshu, LI Ziyi, YANG Xiong
    2014, 65(10):  3953-3959.  doi:10.3969/j.issn.0438-1157.2014.10.028
    Abstract ( 396 )   PDF (620KB) ( 338 )  
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    The relationship between adsorption rate and adsorbate quantity of a single particle, and the adsorbate concentration distribution changing with time inside the particle were studied based on the solid surface diffusion model. Referring to the assumption of LDF in literature, it was found that assuming a parabola distribution of adsorbate concentration inside the particle at the initial time was not suitable, because it caused a lower gradient of particle concentration distribution on the particle surface, and also a lower adsorption rate. A new improved LDF model was put forward, and was verified through the experimental curves of SO2 adsorption on activated carbon. The modified LDF model was more accurate in predictng the breakthrough curves compared with the LDF model.
    Crystallization behavior of AlCl3·6H2O in hydrochloric system
    GUO Yanxia, YANG Xi, CUI Huixia, CHENG Fangqin, YANG Fengling
    2014, 65(10):  3960-3967.  doi:10.3969/j.issn.0438-1157.2014.10.029
    Abstract ( 485 )   PDF (4981KB) ( 643 )  
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    AlCl3·6H2O, one of the most widely used inorganic compounds, is commonly prepared by leaching alumina from coal gangue and coal fly ash. Its quality depends strongly on the crystallization process. In this paper, the crystallization behavior of AlCl3·6H2O in hydrochloride system and the effect of impurities including Fe, Ca, Mg, K and Na on the crystallization were studied. The results showed that the crystallization efficiency of AlCl3·6H2O increased with the volume of concentrated HCl (36% by mass) added. The crystallization efficiency of AlCl3·6H2O reached 80% at 25℃ when the volume ratio of HCl to AlCl3 solution was 2.25. The presence of Fe improved the crystallization efficiency of AlCl3·6H2O slightly. The content of Fe in AlCl3·6H2O crystallized from 1.5 mol·kg-1 of AlCl3 solution was < 0.1% by mass when the molar ratio Al:Fe was less than 3:1. Little effects of K, Ca, Mg and Na on the crystallization of AlCl3·6H2O were observed. Furthermore, the effect of feeding speed of concentrated hydrochloride on the particle size distribution and morphology of AlCl3·6H2O crystallization was investigated by focused beam reflectance measurement and particle vision measurement. It is demonstrated that a fast feeding speed of hydrochloride results in the formation of agglomerated crystals with small size, while a slower feeding speed leads to the formation of dispersive single-crystals with larger sizes and improved morphologies.
    Fabrication of high flux polyethersulfone nanofiltration membrane for dye concentration and desalination
    HUANG Jian, SHU Zengnian, ZHANG Sihai
    2014, 65(10):  3968-3975.  doi:10.3969/j.issn.0438-1157.2014.10.030
    Abstract ( 483 )   PDF (1642KB) ( 606 )  
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    High flux of polyethersulfone (PES) nanofiltration (NF) membrane was fabricated with triblock copolymer Pluronic F127 as additive using a special casting machine by phase inversion method for dye concentration and desalination. The effects of additive content in the casting solution, solvent evaporation temperature and evaporation time during membrane fabrication on the structure and performance of the PES NF membrane were examined, and the separation performance of the PES NF membrane for dyes at different operation pressure and temperature was investigated. The scanning microscopy observation, contact angle test, porosity data and protein adsorption test show that the pore structure of the membrane is improved, its porosity and antifouling performance are enhanced with the addition of Pluronic F127. Pure water flux, rejection and membrane surface pore size characterization indicate that with the Pluronic F127 content in the caste solution at 3%, the solvent evaporation temperature at 90℃ and the solvent evaporation time at 18 s, the fabricated membrane presents the best separation performance. The rejection of the PES NF membrane for Eriochrome Black T is 99%, with a flux of 110.2 L·m-2·h-1, while the rejection for NaCl is only 5.5% at 0.6 MPa. The desalination and purification experiment exhibits that the rejection for the dye remains over 99% throughout the whole experiment, indicating that the PES NF membranes could be successfully applied in the dye purification and desalination process.
    Step-by-step retrofit of heat exchanger network with heat pump installation and multi-objective optimization strategies
    KANG Lixia, LIU Yongzhong
    2014, 65(10):  3976-3983.  doi:10.3969/j.issn.0438-1157.2014.10.031
    Abstract ( 731 )   PDF (658KB) ( 289 )  
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    In order to investigate the comprehensive effects of heat pump installation on energy saving and CO2 emission reduction in heat exchanger network (HEN) retrofit, a step-by-step multi-objective optimization model with combination of multiple strategies was proposed for HEN retrofit, in which the objective was to minimize the annual HEN retrofit cost and newly increased CO2 emissions. A HEN retrofit problem of a benzol-ketone dewaxing unit was taken to illustrate the effectiveness of the proposed method. The Pareto fronts that represented the trade-offs between economy and CO2 emission were presented. The location of heat pump installation in HEN was discussed. For the three retrofit strategies, the effects of economy, CO2 emission and energy saving were compared and analyzed. The proposed method would provide theoretical fundamentals for formulating schemes of energy conservation and CO2 emission control in process industries.
    Online optimization implementation on model predictive control in chemical process
    LUO Xionglin, YU Yang, XU Jun
    2014, 65(10):  3984-3992.  doi:10.3969/j.issn.0438-1157.2014.10.032
    Abstract ( 416 )   PDF (750KB) ( 298 )  
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    Multi-layer model predictive control has become the mainstream method in industrial process control. Based on this control structure, original steady-state optimization was embodied in two main situations according to different desired values obtained from the operator or upper process optimization. An optimization problem with a compound objective function was proposed to calculate the target for MPC, which could degenerate into linear or quadratic form or the combination of both due to diverse process requirements. In order to ensure that ultimate optimal target was feasible and critical variables were not saturated, adjustment measure was taken when it was infeasible. Aiming at ensuring the consistency of variables between optimization implementation and MPC, the optimal target was transformed into incremental form. Simulation results of the constrained CSTR system showed that the optimization implementation layer provided appropriate optimal target effectively for MPC towards various process requirements, which demonstrated feasibility of the proposed method.
    Steady state and dynamic control of divided-wall column for separating aromatics
    YANG Jian, SHEN Benqiang, LIN Xiyu, WU Hao, LING Hao
    2014, 65(10):  3993-4003.  doi:10.3969/j.issn.0438-1157.2014.10.033
    Abstract ( 491 )   PDF (2183KB) ( 350 )  
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    Divided-wall column (DWC) has many advantages over conventional columns, such as energy saving potential and low investment cost. A new DWC sequence for separating benzene, toluene, o-xylene and 1,3,5-trimethylbenzene quaternary mixture was proposed and simulated in this study. Rigorous distillation column models in Aspen Plus were employed in all simulations. Under the same targets of purity and yield, the energy consumed by DWC can be reduced by 18.9% and the total annual cost can be saved by 13.0% compared to that of conventional direct separation (DS) sequence. The reason for the energy saving is that DWC could prevent the remixing of intermediate compounds, which often happens in DS sequence. Using Aspen Dynamic, composition controlled structure for DWC is proposed, which controls the new DWC separation sequence and minimizes the energy consumption in DWC. The dynamic simulation shows that the composition controlled structure provides effective control of product purity for fluctuations of feed flow rate and composition.
    Dynamic soft sensor modeling and its application using leaky-integrator ESN
    LI Jun, YUE Wenqi
    2014, 65(10):  4004-4014.  doi:10.3969/j.issn.0438-1157.2014.10.034
    Abstract ( 624 )   PDF (967KB) ( 433 )  
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    Soft sensor dynamic modeling based on echo state networks (ESN) with leaky-integrator neurons was proposed, in which the off-line learning algorithm using ridge regression and on-line learning algorithm using recursive least squares (RLS) were given respectively. By adding a regularization coefficient, ridge regression algorithm could control large sizes of output weight matrix and improve the properties of ESN solution. On-line learning algorithm could allow on-line processing of large data sets and attain requirement of real time for process modeling. Leaky integrator ESN (LiESN) was used to estimate the butane(C4) concentration in the bottom flow of a debutanizer column and to compute sulfur recovery unit (SRU) tail gas composition for improving product quality monitoring and control in a refinery. Simultaneously, the modeling performance was evaluated by 4-plot analysis of model residuals. Compared with existing soft sensor modeling such as ESN, support vector machines (SVM) etc, under the same condition, experimental results confirmed that LiESN could achieve better performance and the accuracy of the model could meet practical need.
    Pt/WC-CNTs electrocatalyst for oxygen reduction reaction
    JIN Yanxian, SHI Meiqin, LIU Weiming, CHU Youqun, XU Yinghua, MA Chun'an, JIA Wenping, ZHAO Guojie, YU Jianqing
    2014, 65(10):  4015-4024.  doi:10.3969/j.issn.0438-1157.2014.10.035
    Abstract ( 359 )   PDF (9576KB) ( 652 )  
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    Tungsten carbide/carbon nanotubes composite (WC-CNTs) was prepared through surface decoration and in situ reduction and carbonization technology. Furthermore, its supported Pt electrocatalyst was prepared by the microwave-assisted polyol method. Compared to Pt/CNTs catalyst, Pt/WC-CNTs catalyst showed higher electrocatalytic activities for the oxygen reduction reaction (ORR), with lower overpotential, higher current density and higher exchange current density, lower charge transfer resistance and better selectivity towards ORR. XRD and TEM results indicated that Pt/WC-CNTs catalyst was mainly made of WC, Pt and CNTs. Fine Pt particles were dispersed on outside surfaces of WC-CNTs. Pt nanoparticles were in contact with WC nanopaticles, which was helpful to the synergistic effect between them. Thus, the enhancement in electrocatalytic properties of the novel Pt/WC-CNTs catalyst was attributed to this synergistic effect between Pt and WC. The rotating disk electrode measurements were performed to gain insight into ORR performance on Pt/WC-CNTs catalyst. This observation suggested that a four-electron reduction process took place on the catalyst surfaces. Tungsten carbide/carbon nanotube supported Pt electrocatalysts with low cost and unique activity for ORR have good prospect for development in the fuel cell cathode catalyst research applications.
    Influence of inorganic salts on sodium dodecyl benzene sulfonate microemulsion system
    YUAN Ying, LIU Hui'e, XU Mingming, DING Chuanqin, CHEN Shuang, QI Xuanliang
    2014, 65(10):  4025-4031.  doi:10.3969/j.issn.0438-1157.2014.10.036
    Abstract ( 640 )   PDF (1665KB) ( 475 )  
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    The influence of inorganic salts on sodium dodecyl benzene sulfonate (SDBS)/butanol/octane/water microemulsion system was investigated by changing the type of salts. Increasing cationic charge concentration of various salts in an anionic surfactant microemulsion system promoted changes in the microemulsion phase behavior from lower phase (Winsor Ⅰ) microemulsion through middle phase (Winsor Ⅲ) toward upper phase (Winsor Ⅱ) microemulsion. While for different inorganic salts, optimum salinities were different. Six groups of salt mixture systems were investigated. There was a linear relationship between efficiency parameter of salt mixtures and their composition, in other words, the influence of salt mixtures could be predicted by studying efficiency parameter of single inorganic salts. By using efficiency parameter as the medium, the relationship between optimum salinity of single salts and their mixtures was deduced, and could be used to predict the influence of salt mixtures. The prediction results coincided well with the experimental results.
    Electrochemical analysis of inhibition by silver sulfate for Alloy690 in chloride solution
    HU Jun, WANG Yun, YU Lijun, ZHENG Maosheng, ZHAO Yuan
    2014, 65(10):  4032-4038.  doi:10.3969/j.issn.0438-1157.2014.10.037
    Abstract ( 440 )   PDF (768KB) ( 257 )  
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    According to the self-catalytic effect of chloride ion in corrosion process, a new method based on Ag2SO4 as corrosion inhibitor was developed to reduce local corrosion. The corrosion inhibition effect of Ag2SO4 on Alloy690 was studied in 0.005 mol·L-1 NaCl solution by using Tafel polarization curves, electrochemical impedance spectroscopy(EIS) and X-ray photoelectron spectroscopy(XPS). The corrosion current density was greatly decreased. This indicated that (AgCl2)- or (AgCl3)2- between silver ion and chloride ion were formed to decrease activity of chlorine ion in corrosion solution. The adsorption of the complex compound would change the double-layer structure from two layers to three layers, inhibiting the anodic oxidation process of Alloy690. With the increase of concentration of Ag2SO4, equilibrium potential would rise, and capacitance of the solid/liquid interface would decrease. Better inhibition effect than other cases could be achieved when the concentration of silver sulfate and sodium chloride ratio equaled to 0.2. Therefore, silver sulfate is a good corrosion inhibition for Alloy690 in chloride solution.
    Corrosion inhibition and olecular structure of thiadiazole derivatives in sulfur-ethanol system
    LIU Lin, PAN Xiaona, ZHANG Qiang, QIAN Jianhua
    2014, 65(10):  4039-4048.  doi:10.3969/j.issn.0438-1157.2014.10.038
    Abstract ( 336 )   PDF (3975KB) ( 261 )  
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    The inhibition performances of thiadiazole derivatives, namely, 2-amino-1,3,4-thiadiazole (ATD), 5-metheyl-2-amino-1,3,4-thiadiazole (MATD), 5-phenyl-2-amino-1,3,4-thiadiazole (PATD), and 2,5-diphenyl- 1,3,4-thiadiazole (DPTD), on silver strip corrosion in 50 mg·L-1 sulfur solution was studied using electrochemical impedance spectroscopy (EIS), Tafel polarization techniques and atom force microscopy (AFM). These measurements showed that the addition inhibited silver strip corrosion, and the inhibitor formed a protected film on the silver strip surface. The inhibition efficiency decreased in the order of MATD > PATD > ATD > DPTD. The substitutes, which occupied 1 or 2 sites on the central five membered ring and had polar groups and non-polar groups properties and some active functional groups showed an important effect on the inhibition performance of thiadiazole derivatives. Compounds showed the best inhibitive efficiency when thiadiazole derivatives had the polar groups and the best inhibitive efficiency when non-polar groups were alkyl groups, because steric exclusion of aromatic groups decreased the adsorption. Kinetics analysis indicated that adsorption of the four inhibitors onto silver surface followed Langmuir adsorption isotherm. The adsorption belonged to mix-type adsorption mainly dominated by chemisorption. The inhibition mechanism of four corrosion inhibitors against sulfur corrosions was theoretically studied using molecular dynamics simulations. The results indicated that the ring thiadiazole and heteroatom of the polar group on the hydrophilic chain were preferentially adsorbed when the inhibitors reacted with metal surface, and the theoretical calculation accorded well with experimental results.
    Protection performance of silane pretreatment/Mγ-Al rich epoxy coating for aluminum alloy
    ZHANG Qian, ZUO Yu, TANG Yuming
    2014, 65(10):  4049-4055.  doi:10.3969/j.issn.0438-1157.2014.10.039
    Abstract ( 413 )   PDF (6887KB) ( 289 )  
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    A silane film was formed on LY12 aluminum alloy and the effect of silane pretreatment on the performance of a Mγ-Al rich primer on LY12 alloy were studied. After silane treatment, Si-O-Al covalent bonds were formed between aluminum alloy substrate and silane film and Si-O-Si structure was formed in silane film. In addition, silanol groups -OH in free form and epoxy groups from silane film might react with organic fractions in epoxy coating to form cross-linked bonding, and these two types of groups were bonded through van de Waals force, forming an interpenetrating polymer network (IPN) across the interface and providing improved adhesion between aluminum substrate and silane film. Machu test and electrochemical measurements indicated that silane pre-treatment significantly improved the performance of the Mγ-Al rich primer on LY12 alloy, which was attributed to strengthened barrier effect of the coating system.
    NO/NH3 adsorption properties on γ-Al2O3 (110) surface during SCR process
    CAO Fan, SU Sheng, XIANG Jun, WANG Pengying, HU Song, SUN Lushi, ZHANG Anchao
    2014, 65(10):  4056-4062.  doi:10.3969/j.issn.0438-1157.2014.10.040
    Abstract ( 495 )   PDF (2690KB) ( 600 )  
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    γ-Al2O3 is an outstanding catalyst carrier and has been widely used in the SCR (selective catalytic reduction) catalyst study. The adsorption and reaction properties of NO/NH3 on the bare and defective γ-Al2O3 (110) surface were studied by the DFT (density functional theory) method. The corresponding microscopic parameters, such as adsorption energies, bond length, changes of net charge and PDOS (partial density of states) were calculated. NO could be adsorbed on the bare (110) surface weakly, and it was more inclined to be adsorbed on the top sites of O2c. NH3 could be adsorbed strongly on top sites of Al. The rate-determining step of SCR reaction was the -NH2NO decomposition, while the largest energy barrier reached 235.75 kJ·mol-1. For the defective (110) surface with the oxygen vacancy, NO and NH3 could be both adsorbed strongly on the surface, and NH3 could also decompose into NH2 and H directly in this situation. The largest energy barrier of SCR reaction in this situation was much lower, indicating that the presence of oxygen vacancy could promote SCR reaction proceeding.
    Effects of key operating parameters on SCR performance of diesel engines
    TAN Piqiang, DU Jiazhen, HU Zhiyuan, LOU Diming
    2014, 65(10):  4063-4070.  doi:10.3969/j.issn.0438-1157.2014.10.041
    Abstract ( 415 )   PDF (796KB) ( 340 )  
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    A simulation model for selective catalytic reduction (SCR) of exhaust gas from diesel engine is established, and a concept of urea decomposition efficiency is proposed. Effects of exhaust gas temperature, NH3 storage, NO2/NOx ratio and NH3/NOx ratio on the NOx conversion efficiency are studied. The results show that the urea decomposition efficiency increases with decreasing exhaust gas flow rate and rising exhaust gas temperature. Special evaluating experiments for NOx conversion efficiency under various temperatures were performed. The data obtained by simulation show good agreement with the experimental results. The results show that the NOx conversion efficiency increases with the NH3 storage capacity rising. Similarly, the NOx conversion efficiency increases with rising exhaust gas temperature, and it gets stable when the exhaust gas temperature reaches a certain value. Increasing NO2/NOx ratio can also improve the NOx conversion efficiency, but the opposite phenomenon occurs when the NO2/NOx ratio is greater than 50%. With increase of NH3/NOx ratio, the NOx conversion efficiency ascends, and the influence is obvious when the exhaust gas temperature is high.
    Denitrification characteristics in oxygen-enriched continuous anoxic/aerobic biofilm system for municipal wastewater treatment
    HU Jiawei, LI Jun, BIAN Wei, ZHENG Linxue, WANG Meng
    2014, 65(10):  4071-4077.  doi:10.3969/j.issn.0438-1157.2014.10.042
    Abstract ( 342 )   PDF (1671KB) ( 223 )  
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    For municipal wastewater treatment, a continuous anoxic/aerobic system (A/O) combined with flow separate filler was developed to investigate nitrogen removal performance. A/O was running stably for 113 days under oxygen-enriched condition (dissolved oxygen, DO>1.5 mg·L-1). Removal of ammonia nitrogen and total nitrogen reached 50%, while nitrite and nitrate were not accumulating during the stable process. Simultaneous nitrification and denitrification was obvious in the aerobic zone. 16S rDNA results showed that functional bacterias were aerobic denitrifying bacteria (ADB) in the biofilm of the aerobic zone, and FISH results showed the activities of ADB along the aerobic zone. Aerobic denitrification was the main form of simultaneous nitrification and denitrification in the system, consuming nitrite and nitrate from nitrification. A nitrogen removal pathway model via simultaneous nitrification and denitrification in the biofilm under oxygen-rich water environment was established.
    Parametric optimization and performance analysis of subcritical organic Rankine cycle based on multi-objective function
    WU Shuangying, YI Tiantian, XIAO Lan
    2014, 65(10):  4078-4085.  doi:10.3969/j.issn.0438-1157.2014.10.043
    Abstract ( 602 )   PDF (523KB) ( 399 )  
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    A multi-objective optimization model is built, which incorporates the net power output Wnet, exergy drop of exhaust fluid from inlet to outlet ΔEg, total exergy destruction rate I, and total cost C2013 of system into one function, and solved with the method of linear weighted evaluation function. Taking single working fluids R600a, R245fa, R601a and Pentane, and non-azeotropic mixed working fluids R600a/R601a, R245fa/R601a, R245fa/Pentane, and R600a/R245fa as examples, the evaporation temperature Te and condensation temperature Tc of subcritical organic Rankie cycle (ORC) are optimized. The results reveal that sometimes the optimal point can not be obtained using single-objective function, while it always can with multi-objective function. Moreover, the multi-objective optimization of ORC seems superior to single-objective optimization, because the multi-objective optimization coordinates the relationships among various performance indicators, which makes each indicator reach the optimal point as possible. Additionally, there exists optimal evaporation temperature Te,opt and condensation temperature Tc,opt minimizing the multi-objectivefunction F(X) values, but they vary with working fluids. For multi-objective optimization at Te,opt and Tc,opt, the comparisons of different single-objective function values and F(X) between non-zeotropic mixed working fluids and single working fluids show that the ORC performance of mixed working fluids is not always better than that of single working fluids.
    Ammonia escape control in carbon dioxide capture using ammonia method
    MA Shuangchen, CHEN Gongda, MA Xiaoying, GUO Meng, HAN Tingting, SONG Huihui
    2014, 65(10):  4086-4093.  doi:10.3969/j.issn.0438-1157.2014.10.044
    Abstract ( 528 )   PDF (1265KB) ( 285 )  
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    This paper focuses on ammonia evaporation in ammonia-based CO2 capture. Based on our previous research, glycerol and Co(Ⅱ) with promising effect on controlling ammonia escape were studied. The mechanisms of controlling ammonia escape using glycerol and Co(Ⅱ) were analyzed with IR, UV, XRD and the impact on CO2 removal and desorption was investigated. Both glycerol and Co(Ⅱ) could control ammonia escape with average efficiency of above 40%. Glycerol and Co(Ⅱ) had no significant effect on absorption of carbon dioxide, while Co(Ⅱ) could promote desorption of CO2.
    Enhanced nutrient removal in improved A2N-IC-SBR process
    SHI Jing, LÜ Xiwu, XU Zhengwen, WU Qingqing, FANG Mengyuan
    2014, 65(10):  4094-4100.  doi:10.3969/j.issn.0438-1157.2014.10.045
    Abstract ( 443 )   PDF (4765KB) ( 246 )  
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    To solve the problem of the unsatisfactory effluent ammonia concentration in the A2N-IC-SBR (anaerobic/anoxic/nitration-induced crystallization-sequencing batch reactor) process, improvement measures were taken. Nutrient removal performance was investigated in the improved system. Ammonia removal rates increased significantly without any negative effect on phosphorus removal. After the improvement measures, effluent ammonia, total nitrogen and total phosphorus all reached the Chinese National Sewage Discharge Standard Class I (grade A) level. Compared with A2N-IC-continuous flow process, obvious advantage of enhancing phosphorus recovery was noticed. Calcium could be added continuously and evenly during the chemical phosphorus recovery reaction stage, benefiting heterogeneous precipitation. And plate-shaped crystallization product was formed on the seeds.
    Reaction mechanism of K2CO3/Al2O3 sorbents for CO2 absorption
    ZHANG Zhonglin, LIU Daoyin, DONG Wei, WU Ye, MENG Qingmin, CHEN Xiaoping
    2014, 65(10):  4101-4109.  doi:10.3969/j.issn.0438-1157.2014.10.046
    Abstract ( 460 )   PDF (3155KB) ( 406 )  
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    The carbonation characteristics of K2CO3 sorbents and K2CO3/Al2O3 supported sorbents for CO2 capture were investigated with thermogravimetric apparatus (TGA), scanning electron microscopy analysis (SEM) and N2 adsorption. The surface areas and porosities of the sorbents were greatly improved after loading, which led to increase of reaction rate and conversion percent. It meant that carbonation characteristics of sorbents were improved. The reaction rate and conversion percent decreased with increasing diameter of pure K2CO3 sorbents, and slightly increased with increasing diameter of K2CO3/Al2O3 sorbents. The influence of different diameters and reaction times on the particle micro structure was studied, and the result showed a steady micro structure of the particle. A supported particle model was used to describe the carbonation process of K2CO3/Al2O3 sorbents and the model results agreed well with experimental data. The influence of different CO2 concentrations on K2CO3/Al2O3 sorbents carbonation was computed by the model. The simulation result was reasonable and accurate, providing a foundation for further study.
    Extraction of valuable Si and Mg components from boron mud by roasting-leaching
    JIANG Tao, ZHANG Qiaoyi, JIANG Yujiao, XUE Xiangxin
    2014, 65(10):  4110-4117.  doi:10.3969/j.issn.0438-1157.2014.10.047
    Abstract ( 376 )   PDF (7172KB) ( 250 )  
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    Based on TG-DTA analysis, boron mud, the solid waste of boron chemical industry, was roasted in a muffle oven and a microwave furnace at different temperatures, and the roasted products were processed through alkaline leaching and acid leaching to extract separately valuable Si and Mg components. The effects of roasting methods and temperature on leaching rates of SiO2 and MgO were investigated. Chemical and phase compositions as well as micro-structures of the roasting products, obtained silica and magnesium oxide were analyzed and characterized by chemical analysis, XRD and SEM. The results indicate that the activity of the boron mud increases after both two types of roasting. The optimal process parameters are 600℃ and 30 min for the roasting in muffle oven and 500℃ and 10 min for doing in microwave furnace. At these conditions, the leaching rates of SiO2 and MgO reach 97.65% and 98.81% for former and 98.03% and 98.83% for later, respectively. The silica prepared, containing 92.20% SiO2, consists of nearly spherical grains with diameter ranges from 100 to 200 nm. And the magnesium oxide obtained, containing 93.05% MgO, makes of plate-like grains with diameter about 2 mm.
    Mechanism of removing arsenic and cadmium with ferric chloride
    GUO Li, ZHAO Yanpeng, DU Dongyun
    2014, 65(10):  4118-4122.  doi:10.3969/j.issn.0438-1157.2014.10.048
    Abstract ( 432 )   PDF (576KB) ( 528 )  
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    The mechanism of arsenic and cadmium removal withferric chloride was studied by analysis of residue samples with CD-MUSIC, XPS, FTIR and Zeta potential. There was interference between As and Cd by competing the active site on iron oxide in the range of pH at 3-7. Nevertheless, in the range of pH at 7-10, Cd(Ⅱ) was mainly removed by precipitation as Cd(OH)2, which could increase As removal by co-precipitation. According to the results simulated with CD-MUSIC, As(Ⅴ) was mainly removed by forming monodentate uninuclear surface complexes ( FeOAsO3H1.5- and FeOAsO(H2O)20.5-), with binding constants of 63.04 and 66.50 respectively. Besides, Cd(Ⅱ) was combined on the surface of ferriferrous oxide with the formation of FeOHCd1.5+ with binding constant of 31.05 and the amount of this complex decreased with rising pH.
    Properties and structure of rosin acid starch ester prepared by enzyme catalysis
    LI He, LIN Rihui, SU Jiating, WU Jia, WEI Chunyu, LI Xunbi
    2014, 65(10):  4123-4130.  doi:10.3969/j.issn.0438-1157.2014.10.049
    Abstract ( 281 )   PDF (2805KB) ( 255 )  
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    Rosin acid starch esters with degree of substitution (DS) ranging from 0.031 to 0.092 were prepared by enzymatic esterification reaction, using rosin acid and cassava starch as raw material, DMSO as solvent, and its physicochemical characters were also studied. The results showed that with the increase of DS, the swelling power and solubility of esterification products reduced, relative and intrinsic viscosity increased, and the molecular chain of esterified starches grew. The data from UV analysis on the starch-iodine complexes indicated that the maximum absorption wavelength moved to longer wavelength when the DS increases, together with the blue value declines. The rosin acid starch esters with different DS were characterized by FT-IR, 1H NMR, DSC, TGA and SEM. The results indicated that the esterified product exhibited a new absorption band at 1727 cm-1, which was assigned to the attribution of the symmetric deformation vibration of carbonyl C O. Compared with the pretreated starch, the gelatinization temperature and thermal stability of rosin acid starch esters were reduced, and the crystallinity also decreased.
    Experimental analysis of ice-making characteristics with adsorption in vacuum environment
    ZHANG Xuelai, ZHAO Qunzhi, MENG Xianglai, LI Chunlei, XU Bin
    2014, 65(10):  4131-4137.  doi:10.3969/j.issn.0438-1157.2014.10.050
    Abstract ( 329 )   PDF (2926KB) ( 276 )  
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    Based on the theory of vacuum flash of water, a flash device is designed for experiment of ice-making under the condition of adsorption. Vacuum preparation of binary ice makes use of the principle of the triple point of water. However, the water flash will inevitably increase the chamber pressure and the pressure will be higher than the triple point (611 Pa). This paper proposes a method using solid adsorbent to maintain the pressure. Based on the initial establishment of a low pressure environment, the flash vapor can be adsorbed by the solid zeolite adsorbent in the closed system. Due to the experimental conditions, only the effect of adsorption modules on the flash is analyzed. At certain preset pressure (400, 600, and 800 Pa), height of liquid film (20-50 mm) and initial temperature (32℃, 22℃), comparative experiments are carried out in the presence or absence of adsorption module. The results show that the flash chamber pressure and temperature of liquid film can be reduced faster with the adsorption. With the adsorption module, vacuum flash of water can be enhanced. With smaller height of liquid film, the flash chamber pressure decreases more quickly at the same initial temperature and preset pressure.
    Structure and performance of dye dispersant sodium lignosulfonate with different molecular weight
    YANG Dongjie, LI Huijing, BAI Mengxian, QIU Xueqing
    2014, 65(10):  4138-4144.  doi:10.3969/j.issn.0438-1157.2014.10.051
    Abstract ( 717 )   PDF (662KB) ( 463 )  
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    Three purified sodium lignosulfonate (SL) samples with various molecular weights were prepared by fractionation using ultrafiltration.The structural characteristics of SL samples and its effect on performance of dye are investigated by means of gel permeation chromatography, ultraviolet spectrophotometry, electrolytic titration and high temperature dying process. The results show that, with increase of molecular weight, the color of SL becomes darker, its purity increases, and the content of guaiacyl increases while phenolic hydroxyl, carboxyl and sulfonic decrease. The SL with high molecular weight is of good dispersibility and high temperature stability for dispersing dyestuff, and the dyeing rate of dyestuff increases also with increase of SL molecular weight. The staining of SL for fiber could be weakened when its molecular weight is larger and its concentration is higher. In addition, the reduction destruction of SL for dyestuff depends on molecular weights and the content of phenolic hydrophilic group. The SL fraction with molecular weight above 2.5?103 can make dyestuff the most excellent levelling property and the lowest reduction effect, the reduction and hydrolysis rate reduce from 26.0% of unpurified SL to 6.9%.
    Selective inhibition effect of free nitrous acid on ammonium oxidizing bacteria and nitrite oxidizing bacteria under anoxic condition
    WEI Yan, WANG Shuying, MA Bin, PENG Yongzhen
    2014, 65(10):  4145-4149.  doi:10.3969/j.issn.0438-1157.2014.10.052
    Abstract ( 514 )   PDF (479KB) ( 394 )  
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    In order to study the selective inhibition effect of free nitrous acid (FNA) (0.27 mg HNO2--N·L-1) on ammonium oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) under anoxic condition, both the variations of ammonium oxidation rate and nitrite oxidation rate and recovery of AOB reactivity and NOB reactivity were investigated by using the sludge treated by FNA for 6 h under anoxic condition. AOB and NOB reactivities decreased by 83.57% and 22.34% respectively after the sludge was subjected to treatment with FNA. NOB reactivity did not recover when the FNA-treated sludge was used under normal operation environment for 34 cycles. Especially, nitrite accumulation ratio increased gradually and remained over 90%. Moreover, concentrations of nitrogen compounds in the typical cycle showed that nitrite accumulation was not destroyed even if excessive aeration lasted for 2 h. Thus, the selective inhibition effect of FNA under anoxic condition could be used to establish stable nitritation in sewage treatment system, providing the foundation for achieving nitrogen removal from sewage via nitritation and Anammox.
    Hydrothermal liquefaction of waste meat for liquid fuel
    ZHENG Jilu, KONG Yongping
    2014, 65(10):  4150-4156.  doi:10.3969/j.issn.0438-1157.2014.10.053
    Abstract ( 511 )   PDF (590KB) ( 280 )  
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    This paper presents an investigation of hydrothermal liquefaction of waste meat for liquid fuel. Pork from diseased dead pigs was used as feed stock for liquid fuel production. The effects of process parameters (temperature and pressure) on the yields of liquid fuel and solid residue were determined. Heat value, viscosity, flash point, cold filter plugging point, elemental analysis and chemical composition of the liquid fuel were determined and analyzed. The obtained liquid fuel had calorific value of 39.31 MJ·kg-1, viscosity(20℃) of 20.5 mPa·s, flash point of 70℃ and cold filter plugging point of 8℃ under operating conditions (250℃, 4.0 MPa). The liquid fuel was a complicated mixture mainly consisting of aromatic hydrocarbon, ketones, ethers , esters, furan, and a few acids. The liquid fuel could be used as fuel in boiler or furnace for heat generation, and might be a potential resource of automotive fuel after refining.
    Molecular simulation: temperature responsiveness of block copolymer PEO-PPO-PEO and underpinned mechanism
    CHEN Gong, ZHU Jingying, GE Jun, LU Diannan, LIU Zheng
    2014, 65(10):  4157-4167.  doi:10.3969/j.issn.0438-1157.2014.10.054
    Abstract ( 475 )   PDF (9134KB) ( 660 )  
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    Molecular dynamics simulation at all atoms level was used to probe the temperature induced phase transition behavior of single-chain block copolymer PEO-PPO-PEO, represented by Pluronic P85, in different solutions. A negative temperature responsiveness of Pluronic P85 in polar solvent such as water and methanol was observed, in which the increase in temperature promoted the breakage of hydrogen bonds between the PPO and PEO respectively with the solvents and thus resulted in the desolvation of PPO and PEO. This thus led to collapse of the polymer as a result of enhanced intramolecular interaction and the release of solvent molecules. On the contrary, a positive temperature responsiveness of Pluronic P85 was shown in toluene, in which the increase in temperature weakened the intramolecular interaction and thus enabled conformational flexibilities. The temperature responsiveness of the solvation of PEO and PPO block was also simulated, which offered a theoretical basis for the molecular design and applications of these PEO-PPO-PEO block copolymers.
    Synthesis and characterization of block copolymers of poly(silane arylacetylene) and poly(siloxane arylacetylene)
    WANG Qiang, YANG Jianhui, YUAN Qiaolong, HUANG Farong, DU Lei
    2014, 65(10):  4168-4175.  doi:10.3969/j.issn.0438-1157.2014.10.055
    Abstract ( 336 )   PDF (602KB) ( 241 )  
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    A series of block copolymers of poly(silane arylacetylene) and poly(siloxane arylacetylene) (SiO-b-PSA) were synthesized by the condensation reactions of m-diethynylbenzene magnesium reagents with various a,w-bis(chloro)dimethylsiloxanes. Carbon fiber reinforced composites were prepared through compression molding. The structures and properties of the resins and composites were characterized by FT-IR, 1H NMR, GPC, DSC, TGA and mechanical tests. The copolymers had good heat resistance and toughness. The copolymers also showed excellent processability that could be cured at below 200℃. The cured resins possessed high thermal and thermooxidative stability. Their thermo-decomposition occurred at above 513℃ in N2. Impact strength of the composites arrived at as high as(30.92±0.44) kg·m-2.
    Influence of cross section of cavity on water penetration during overflow water-assisted injection molding process
    KUANG Tangqing, YU Chuncong, DENG Yang, ZHANG Kai
    2014, 65(10):  4176-4182.  doi:10.3969/j.issn.0438-1157.2014.10.056
    Abstract ( 504 )   PDF (3269KB) ( 357 )  
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    Experimental study on the influence of the cross section of cavity on water penetration during overflow water-assisted injection molding (OWAIM) process was conducted based on a lab-developed water-assisted injection molding system. The lab-developed water-assisted injection molding system consisted of a water injection unit, an injection machine, a mold with changeable inserts and control unit. Seven cross sections were used as characteristic sections. Circle ratio was introduced to characterize the shape of cross section. Area of cross-section (ACS), the maximum distance between inscribed circle center and wall (Max_D), radius of inscribed circle (RIC) of cross-section, and circle ratio were calculated as import geometry information of cross-sections. Hollow ratio was used to describe the relative void volume of water penetration. The influences of the shape and area size of cavity cross section on the shape of water penetration section and hollow ratio and residual wall thickness (RWT) were studied. In the OWAIM process, the shape of water penetration tended to approach the shape of mold cavity cross section. If the mold cavities had the same or similar cross section area, the mold cavity with a larger circle ratio would have a larger hollow ratio. If the mold cavities had the same or similar circle ratio, the area size of cavity cross section had little effect on hollow ratio. The size of water penetration section was relatively constant in a cavity with constant cross section. The residual wall thickness of a cavity with circular section was uniform. The larger the cross section, the thicker the RWT. For the cross sections with the same radius of inscribed circle (RIC), the maximum RWT increased proportionally as Max_D increased, while the minimum RWT decreased proportionally as Max_D increased. And the RWT inhomogeneity increased significantly as Max_D increased. For these cross sections with close Max_D, the higher the RIC, the thicker the maximum RWT and the minimum RWT.
    Influence of calcium/aluminum ratio on microstructure and leaching of 11.3CaO·7Al2O3
    WANG Bo, ZONG Shufeng, SUN Huilan, ZHANG Jianxin
    2014, 65(10):  4183-4190.  doi:10.3969/j.issn.0438-1157.2014.10.057
    Abstract ( 641 )   PDF (11502KB) ( 534 )  
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    Calcium aluminate clinkers with different calcium/aluminum ratios (C/A) were obtained by the high-temperature sintering method. Phase composition, phase semi-quantitative content and crystal constant of sinter were studied with different C/A by XRD. SEM and EDS were used to observe microstructure and element contents. The alumina leaching property of sinter was studied. When C/A was lower than 1.6, the products were CaO·Al2O3 and 11.3CaO·7Al2O3 (C11.3A7) and increase of calcium/aluminum ratio could lead to increase in the content of C11.3A7 and leaching ratio of alumina. When C/A was 1.6, the phase was almost completely C11.3A7 and the leaching rate of alumina reached a maximum. When C/A was higher than 1.6, the products were C11.3A7 and 3CaO·Al2O3, and the leaching rate of alumina decreased accordingly. The lack of CaO in C11.3A7 lattice improved the leaching reaction.
    Deposition of MgO film by pyrolysisof bischofite through RF thermal plasma process
    ZHANG Haibao, CAO Tengfei, CHENG Yi
    2014, 65(10):  4191-4196.  doi:10.3969/j.issn.0438-1157.2014.10.058
    Abstract ( 491 )   PDF (2444KB) ( 268 )  
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    Salt lake resources are rich in China, and the Qarham salt lake in Qinghai Province is the largest potash fertilizer manufacturing base. However, a large amount of byproduct bischofite (MgCl2·6H2O) of the potassium fertilizer industry cannot be utilized effectively and are discarded back into the salt lakes. This has become the primary problem after extraction of potassium from salt lake. This paper presents a thermal plasma process for pyrolysis of bischofite. Thermal plasma was used as an ultra-high heat source to intensify the pyrolysis process. At the same time, the high temperature pyrolysis products were deposited to obtain high value-added MgO film. The deposition efficiency of MgO film was high, up to 3.2 mm·min-1. The particle size on the film was between 10 and 60 nm, and the MgO film exhibited a strong ultraviolet-green photoluminescence emission under the excitation of 325 nm He-Ne laser. The thermal plasma technique is simple and suitable for large-scale continuous process.
    Properties of poly(lactic acid)/epoxidized soybean oil blends
    ZHAO Yongqing, CHEN Fuquan, FENG Yanhong, QU Jinping
    2014, 65(10):  4197-4202.  doi:10.3969/j.issn.0438-1157.2014.10.059
    Abstract ( 415 )   PDF (2369KB) ( 318 )  
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    Poly(lactic acid) (PLA) and epoxidized soybean oil (ESO) was melt blended to prepare the PLA/ESO blends with high toughness. The effects of ESO contents on the phase morphologies, mechanical and rheological properties of the prepared PLA/ESO blends were investigated. The introduction of ESO significantly decreased melt viscosity and improved toughness of PLA. The PLA/ESO blend with low ESO content (10%) was a partially miscible system, whereas that with high ESO content (20% and 30%) exhibited distinct phase separation. Elongation at break and impact strength of the blends increased firstly and then decreased with increasing ESO content. The former reached the maximum value (17 times that of PLA) at ESO content of 20%, and the latter reached the maximum value (2.9 times that of PLA) at ESO content of 15%. Tensile strength of the blends decreased with increasing ESO content.
    Numerical simulation of oil vapor leakage from external floating-roof tank
    ZHAO Chenlu, HUANG Weiqiu, ZHONG Jing, WANG Wenjie, XU Xianyang, WANG Yingxia
    2014, 65(10):  4203-4209.  doi:10.3969/j.issn.0438-1157.2014.10.060
    Abstract ( 455 )   PDF (907KB) ( 333 )  
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    It is important to investigate the oil vapor leakage and emission from external floating-roof tanks for the loss evaluation and potential danger control. The oil vapor leakage from the annular space between the rim and the tank shell is one of the major sources for the evaporation loss. The vapor leakages from the rim of the single-tray floating roof are simulated numerically using FLUENT and measured experimentally. The effects of tank diameter, roof level and wind speed v on the pressure distribution above the roof surface are investigated. The results are as follows. (1) Numerical results agree with the experimental data. (2) When the ratio of the distance h between floating-roof and tank top to the tank diameter D, h/D, is greater than 1/4, the vapor is more likely to leak from the two opposite sides of the annular space perpendicular to wind direction and the side of the annular space in the upwind. (3) Tank diameter has little effect on the pressure distribution above the roof surface, while h/D and v affect the pressure distribution. Larger h/D lowers the wind pressure of roof center, and smaller h/D lowers the upwind pressure above the roof. When h/D varies from 1/20 to 1/2, the upwind and downwind pressures are negative, and with the decrease of h/D, the differential pressure above the roof increases. API loss formula for external floating-roof tank is recommended to consider the effect of ratio h/D to improve the accuracy in loss evaluation.