CIESC Journal

Isobaric vapor-liquid equilibria for water+acetic acid+n-penyl acetate

CHANG Weixian, XU Xinrong, LI Xinli, GUAN Guofeng, YAO Huqing, SHI Jun

2005, 56(8): 1379-1384.

Abstract ( 630 )

PDF (389KB) ( 302 )

Related Articles | Metrics

Isobaric vapor-liquid equilibria(VLE) data for water-acetic acid, acetic acid-n-pentyl acetate, and water-acetic acid-n-pentyl acetate systems were measured at 101.33 kPa using an improved Rose still. The quality of the measured binary data was verified by using the thermodynamic consistency test.The association of acetic acid in vapor phase was considered.And the nonideality of vapor phase was corrected by Virial and Hayden-O’connell equations. The binary interaction parameters for the determination of liquid phase activity coefficients, expressed by the UNIQUAC and NRTL models, were obtained by applying the nonlinear least square method. The obtained NRTL model parameters from binary data were used to predict the ternary VLE data. For ternary system, the average absolute deviations(AAD) in vapor-phase mole fraction of water and acetic acid were independently 0.0230 and 0.0222 and AAD in the equilibrium temperature was 1.15 ℃.

Determination of critical temperatures and critical pressures of four thermally unstable substances

WANG Xinhong, JIA Qi, GAO Jin, XIA Shuqian, MA Peisheng

2005, 56(8): 1385-1388.

Abstract ( 812 )

PDF (463KB) ( 161 )

Related Articles | Metrics

Critical temperatures and critical pressures of four thermally unstable substances，including butyl acrylate, methyl methacrylate, allyl acetone and allyl alcohol，were measured for the first time via the quick-flow method. In the process，a small amount of sample was heated up to critical state in a very short time as it was passing through a capillary glass tube.The variation relationships of apparent critical properties with residence time were determined and the critical properties data were subsequently obtained by means of extrapolation. Polymerization reaction and other side reactions during the heating up process were minimized thanks to the short residence time less than 12 seconds.Therefore, this method is fit for measuring critical temperature and critical pressure of thermally unstable substance. The reliability of experimental apparatus was verified with 1-heptene as the standard substance whose accurate critical properties can be referred to in literatures.

Modeling and simulation of condensation and dehumidifying of high humidity industrial exhaust gases

YU Hui, ZHU Jiahua, DU Huaiming, XIA Sulan, GUAN Guoqiang, WANG Jiangping, GUO Shiwei, LU Qingguo, ZHANG Hongying

2005, 56(8): 1389-1396.

Abstract ( 753 )

PDF (1296KB) ( 237 )

Related Articles | Metrics

Modeling and simulation of the processes of condensation dehumidifying of high humidity industrial exhaust gases were made.An allocation factor, α, was introduced in the model to quantitatively express the effect of condensation on dehumidification with two existing mechanisms of fogging and film condensation.The profiles of temperature and steam fraction as well as their gradients (the driving forces for heat and mass transfer) were obtained numerically for turbulent flow of exhaust gases in the annular space outside a cooling tube with constant wall temperature.Dehumidification by fogging was mainly controlled by the mechanism of steam supersaturation produced from the cross interaction of heat and mass transfer driven by the temperature and humidity gradients near the cooling wall. While a much rapid heat and mass transfer would be seen in the bulk flow field when film condensation took place.It could be concluded that the actual dehumidification process should reach an inter mediate status between fogging and film condensation.From the pilot experiment of DAP tail gas cooling and dehumidification in the region of 34%—57% reduction of steam fraction, the experimental results obtained were considerably consistent with the simulation results for the allocation factor α=0.2.

Asymmetry of gas-phase flow field in cyclone separator

SONG Jianfei;WEI Yaodong;SHI Mingxian

2005, 56(8): 1397-1402.

Abstract ( 805 )

PDF (951KB) ( 475 )

Related Articles | Metrics

Based on Reynolds stress model(RSM)，the gas-phase flow field in the cyclone separator with volute inlet was numerically simulated and the asymmetric characteristics of the flow field were analyzed.The results indicated that the gas-phase flow field was asymmetric in tube space and cone space, especially in annular space.Because of the asymmetric inlet structure,the axial center of the gas flow vortex deviated from the geometric center of the cyclone.The deviation and direction in different axial positions were different, and the maximum deviation was approximately 0.07R.This caused remarkable asymmetry of radial velocity profiles of the gas-phase flow field.The above stated results were in fair agreement with the experimental data from literature.

Laminar heat transfer inside concentric annular duct in entrance region and effects of variable fluid properties

XIE Gongnan;WANG Qiuwang;TAO Wenquan

2005, 56(8): 1403-1408.

Abstract ( 875 )

PDF (996KB) ( 261 )

Related Articles | Metrics

Laminar flow and heat transfer characteristics of concentric annular duct in the entrance region were numerically investigated by solving two-dimensional steady-state incompressible Navier-Stokes equations. SIMPLER algorithm was used for computation under two boundary conditions. Variations of local Nusselt numbers along axial distance vs Prandtl numbers and radius ratios, as well as the variations due to the effects of variable fluid properties on flow and heat transfer were presented.The correlations of average Nusselt number with Reynolds number, Prandtl number and l/D were also obtained for different radius ratios. It was also found that the annular duct could be used to enhance heat transfer, especially at lower radius ratio. In addition, the higher heat transfer coefficients in the entrance region might also attribute to the higher radius velocity component in this region.

Heat transfer characteristics with impinging circular jet at curved surface

ZHANG Lixiang;HU Guoxin

2005, 56(8): 1409-1412.

Abstract ( 748 )

PDF (406KB) ( 279 )

Related Articles | Metrics

In this paper direct measurements were made to investigate the water jet impingement at the higher temperature curved surface. Heat transfer coefficient at the stagnation point and local area was obtained through the experimentation.The effects of jet impingement exit velocity,nozzle-to-surface spacing and other correlative parameters were investigated in detail.The result showed that the heat transfer coefficient at the stagnation point was higher than at other areas,and it decreased with increasing X/D, but increased with increasing exit velocity.The nozzle-to-surface spacing showed some effect on heat transfer coefficient at a lower exit velocity.

Effect of header configuration on thermal performance of plate-fin heat exchangers

WANG Jiang;LI Yanzhong;ZHANG Zhe;MA Yansong

2005, 56(8): 1413-1418.

Abstract ( 617 )

PDF (558KB) ( 501 )

Related Articles | Metrics

Based on the study of the flow maldistribution in plate-fin heat exchanger,the effect of header configuration on thermal performance and reduction of heat exchanger efficiency caused by the flow maldistribution in heat exchanger was experimentally studied.The experimental results showed that the effect of header configuration on the flow and temperature distribution in heat exchanger was significant.An improved header configuration not only could decrease the time from starting to steady working condition of heat exchanger，but also make the flow and temperature distribution more uniform in heat exchanger.At the same time，the correlation between heat exchanger efficiency and flow maldistribution characteristics was deduced from the experimental data.

Characteristic of gas film between spiral groove dry gas seal faces

JIANG Xiaowen;GU Boqin

2005, 56(8): 1419-1425.

Abstract ( 817 )

PDF (829KB) ( 491 )

Related Articles | Metrics

Spiral groove dry gas seal is a new type,non-contact mechanical seal, which has many advantages such as small leakage, little surface abrasion, low power loss, long service life and high reliability.Utilizing the finite element method, the flow of the gas between the spiral groove dry gas seal faces was investigated by numerical simulation.The pressure distribution of the gas film was obtained.The main seal performance parameters, such as open force, friction force of the face, frictional power loss, axial stiffness and leakage rate were calculated.The influence of the operation conditions and the spiral groove’s geometric parameters on seal performance was also analyzed.The research results provided valuable reference for design of the spiral groove dry gas seal.

Impact of CO₂ mass charge on trans-critical automotive air conditioning system

LIU Hongsheng;CHEN Jiangping;CHEN Zhijiu

2005, 56(8): 1426-1432.

Abstract ( 532 )

PDF (529KB) ( 376 )

Related Articles | Metrics

In this paper, an experiment was carried out to evaluate the impact of CO₂ mass charge on a CO₂ automotive air conditioner.The CO₂ air conditioner was designed to have heat exchanger dimensions nearly identical to conventional R134a systems.The heat exchanger was made of fin-tubes,the compressor was of swash plate design, and a manual expansion valve and an internal heat exchanger accumulator were used. The experimental results show that the coefficent of performance (COP)was strongly related to CO₂ mass charge and the formation of the trans-critical cycle depended on CO₂ mass charge greatly.The COP has a maximum value at a specific CO₂ mass charge. Undercharged CO₂ systems could result in a fast decrease of the cooling capacity and COP;however, overcharged CO₂ systems could cause an abrupt increase of compressor power consumption.The refrigerating cycle displayed different characteristics with different CO2 mass charges.The optimum CO₂ mass charge could be determined according to four state parameters.

Numerical simulation of flow field in cyclone with electrostatic excitation

LI Jiwu;CAI Weijian

2005, 56(8): 1433-1438.

Abstract ( 574 )

PDF (844KB) ( 221 )

Related Articles | Metrics

A one phase,two dimensional turbulent flow model—K-ε model of flow field in ayclone, which consideres the effect of the high-voltage electrostatic fields was developed.K-ε model was dispersed by the control-volume method and solved by the SIMPLE algorithm. Three dimensional velocity profiles in electrostatic cyclone were obtained by numerical simulation, and verified. It was concluded that the shape of velocity profile in flow field had little changed while the values of three dimensional velocities had distinctly changed in the electrostatic field. Three dimensional velocities decreased with increasing diameter of cylinder at the same inlet gas rate.

Modeling of membrane-based absorption of CO₂ into complex solution

LU Jiangang, WANG Lianjun, LIU Xiaodong, SUN Xiuyun, LI Jiansheng

2005, 56(8): 1439-1444.

Abstract ( 658 )

PDF (961KB) ( 503 )

Related Articles | Metrics

A model of differential equations for membrane-based absorption of CO₂ into complex solutions was presented and, interaction between methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) in reactions with CO2 and wetting of the solutions on membrane pores were taken into account in the model.The effects of various factors such as interaction, wetting, modules, liquid and gas velocities, on mass transfer were simulated.Additionally,the effect of the solutions on membrane configuration was analyzed by SEM images.Interaction and wetting were significant non-negligible factors in mass transfer.Overall enhancement factor of complex solution was not summation of that of MDEA and AMP.Membrane resistance rapidly increased and became dominant with partial membrane pores being wetted.Membrane pores were easily wetted at high liquid velocity.SEM images displayed that aqueous solutions of both MDEA and MDEA+AMP made pores bigger and hydrophilic.By taking account of interaction and wetting into model, simulation value was in better agreement with experimental one.

Shape optimization of transversely-ridged tube by orthogonal numerical simulation test

HUANG Weijun;DENG Xianhe;HUANG Debin

2005, 56(8): 1445-1450.

Abstract ( 669 )

PDF (501KB) ( 365 )

Related Articles | Metrics

The experimental scheme of shape optimization of transversely-ridged tube was planned by orthogonal test.The turbulent flow and heat transfer inside every experimental tube were numerically simulated by considering constant property, periodically developed flow and uniform wall temperature. Simulation was conducted by the standard K-ε turbulent model and velocity two-layer zonal model. The numerical results were validated with experimental data or classical data for transversely-ridged tube and smooth tube respectively.η, Nu/Nu_s and f/f_s were presented for every experimental case.The effects of the shape parameters—e/d，p/d, a/e of transversely-ridged tube and the flow parameter—Reynolds number on the thermal-hydraulic performance were analyzed.The results showed that pitch—p/d and rib shape——a/e were the predominant configuration factors and rib height——e/d was not as important as the former ones within the experimental range. The heat transfer efficiency index was found to be strongly influenced by Reynolds number,decreasing sharply with increasing Reynolds number.The optimum configuration was brought forward by analyzing the results of orthogonal test.

Enhanced heat transfer investigation on high viscosity fluid in shell-and-tube exchanger

ZHU Dongsheng;JIANG Xiang

2005, 56(8): 1451-1455.

Abstract ( 902 )

PDF (430KB) ( 346 )

Related Articles | Metrics

It is a key factor to increase heat transfer coefficient of high viscosity fluid in the shell side for making a high performance cooler.The heat transfer and flow resistance performance of trapezoid fin tube high viscosity fluid cooler with helical or segmental baffles were studied, and compared with the heat transfer coefficient of low-fin-tube cooler with segmental baffles. Experimental results indicated that heat transfer film coefficient in the shell side of trapezoid fin tube cooler with entire helical baffles was 60% more higher than that of low-fin-tube cooler with segmental baffles，and pressure drop was lower by 40%. Heat transfer film coefficient in the shell side of trapezoid fin tube cooler with entire helical baffles was 20% more higher than that of trapezoid-fin tube cooler with segmental baffles, and pressure drop was lower by 50%.Heat transfer film coefficient in the shell side of trapezoid fin tube cooler with entire helical baffles was 10% higher than that of trapezoid fin tube cooler with sectional helical baffles, and pressure drop was lower by 19%.Heat transfer film coefficient in the shell side of trapezoid fin tube cooler with segmental baffles was 30% more higher than that of low-fin-tube cooler with segmental baffles, and pressure drop remained unchanged.

Analysis of phase structure of high-density gas-solids downflow

CHEN Hengzhi;LI Hongzhong

2005, 56(8): 1456-1461.

Abstract ( 715 )

PDF (558KB) ( 290 )

Related Articles | Metrics

Experimental study of phase characteristics in a high-density downer (5.6 m tall, 80 mm ID)is presented in this work.Phase time fractions was essentially uniform in the central region, and then increased with increasing(1-ε_av).Dense phase time fraction varied from 10% to 20%,and approximated to dilute phase time fraction.The axial size of dense phase in downer was about 10—15 mm, which was as large as tens times to one hundred times of particles diameter.The averaged solids concentration in the dense phase was as 1.7 times as the local solids concentration, while that in dilute phase was about 40%.The transformation from dense phase to dilute phase in the riser was a sharp transition, while for the downer such transition was gradual.Dense phase in downer was much more difficult to observe than in riser due to its shorter duration time, smaller size and lower density.

Droplet size of two-fluid airblast atomizer with large water/air mass flux ratio

LIU Haifeng, LI Weifeng, CHEN Mouzhi, QIN Jun, XU Jianliang, CAO Xiankui, YU Zunhong

2005, 56(8): 1462-1466.

Abstract ( 764 )

PDF (425KB) ( 473 )

Related Articles | Metrics

Based on the finite stochastic breakup model (FSBM) of the airblast atomization process presented,the atomization process of coaxial two-fluid airblast atomizer with a large water/air mass flux ratio was investigated by using droplet breakup time and motion characteristics of droplet in air streams.The equation of Sauter mean diameter (SMD) with air jet velocity, water jet velocity and diameter, and water/air mass flux ratio was obtained.The experimental results of six coaxial two-fluid airblast atomizers with air and water were obtained by Malvern laser particle sizer of type 3600 measurement.The parameters in the equation of SMD were estimated according to the experimental results.The results showed that the theoretical analysis was reasonable and the relationship of SMD could be used to predict the SMD of coaxial two-fluid airblast atomizer with a large water/air mass flux ratio.

Soft-sphere simulation with unequal particle diameters in gas-solid fluidized beds

WANG Fang;OUYANG Jie

2005, 56(8): 1467-1473.

Abstract ( 914 )

PDF (2070KB) ( 376 )

Related Articles | Metrics

Based on the particle-motion discrete model, a soft-sphere method used for the simulation of fluidization was established in which particle diameters were unequal.The particles motion obeyed the Newton’s second law, and fluid motion was described by the Navier-Stokes equation.The above-mentioned model was used for simulating bubbling and slugging behavior in the fluidized beds.Then the distribution of solids velocities was studied at different gas superficial velocities, stiffness and distributions of particle diameters.Simulation results indicated that the structure of distributor and gas superficial velocity showed some influence on the bubbling phenomena, and the formation, rise and break of bubbles were accelerated with increasing gas superficial velocity.The bigger the stiffness,the quicker the decay of axial solids velocities with increasing time.At the same time, axial solids velocities of wide distribution of particle diameters were bigger than that of narrow distribution.

Frequency analysis of acoustic emission and application in gas-solid fluidized bed

HOU Linxi, WANG Jingdai, YANG Yongrong, HU Xiaoping

2005, 56(8): 1474-1478.

Abstract ( 739 )

PDF (495KB) ( 324 )

Related Articles | Metrics

A model of signal main-frequency measurement was presented for the gas-solid fluidized bed to represent the quantitative relation of main-frequency and particle size,temperature, Young’s modulus and density. The acoustic emission（AE） measurement was completely non-intrusive and not affected by the background noises, and caused to human harm.The experiment based on AE measurement was performed by using a fast Fourier transform (FFT) analyzer in this study. It was found the signals main-frequency decreased with the increasing particle size, temperature, Young〖DK〗’s modulus and density. The experiment in the fluidized bed with i.d. of 150 mm showed that satisfactory agreement was obtained between calculated and experimental data with respect of the main-frequency (LLDPE, HDPE and bimodal polyethylene), and the average errors were all less than 8.3%. The scale-up feasibility of the technical process was discussed by adjusting the elastic partameter. When the AE signals main-frequency model was applied to the industrial fluidized bed of LLDPE, HDPE, bimodal polyethylene, the mean errors between calculated and experimental data were 3.9%，8.2% and 8.8% respectively. By the criterion of the sharp decrease of main-frequency and the sharp increase of amplitude, a novel approach could be developed to judge whether the fluidization runs stably, and it could replace the γ-ray measurement in the future.

Interphase mass transfer of liquid-liquid-solid system in stirred tank

FANG Jing, YANG Chao, YU Gengzhi, MAO Zaisha

2005, 56(8): 1479-1483.

Abstract ( 886 )

PDF (449KB) ( 330 )

Related Articles | Metrics

Volumetric liquid-liquid mass transfer coefficients (k_La) were determined for liquid-liquid-solid dispersion in a mechanically agitated baffled tank by using a conductivity probe.The effects of agitation speed, inert glass bead or PET particle diameter, type of impeller, impeller-to-bottom clearance, and the solids mass fraction on the mass transfer of the typical liquid-liquid extraction system (n-butanol-deionized water-succinic acid) were studied. The experimental results indicated that k_La increased in liquid-liquid and liquid-liquid-solid systems when agitation speed increased. The addition of glass beads enhanced the liquid-liquid mass transfer coefficients, but PET particles decreased the mass transfer rate. In both liquid-liquid and liquid-liquid-solid systems, the Rushton impeller is the most efficient one for mass transfer. The mass transfer coefficient showed a maximum in glass beads systems but decreased slightly in PET systems as the fraction of solid phase increased.For the Rushton impeller, kLa showed a minimum for glass beads systems and increased linearly with the increase of clearance for PET particles.

Distribution of active silver species of Ag/TS-1 catalyst on direct gas-phase epoxidation of propylene

WANG Ruipu, GUO Xinwen, WANG Xiangsheng, WANG Chuanfu, HAO Jingquan

2005, 56(8): 1484-1491.

Abstract ( 610 )

PDF (856KB) ( 184 )

Related Articles | Metrics

The effects of silylation treatment and the template of TS-1 on the catalytic properties of Ag/TS-1 were investigated in a fixed bed, quartz reactor at ambient pressure, using the gas-phase epoxidation of propylene with hydrogen and oxygen as a probe. Moreover, the catalysts were characterized by UV-Vis, ICP and TEM.The results showed that, during the direct gas-phase epoxidation of propylene, the catalytic properties of Ag/TS-1 could be improved when TS-1 was silylanized.When 2%SiO₂ was loaded on TS-1, 2.1% propylene conversion with 98.4% selectivity to propylene oxide (PO) was obtained over Ag/TS-1. The Ag/TS-1 did not show any catalytic selectivity to PO,when the TS-1 powder (with template) was used as the support. Both inner and outer silver species of Ag/TS-1 showed catalytic properties, however, the inner ones were the key active species in the gas-phase epoxidation of propylene.

Novel fixed-bed Raney nickel catalysts(Ⅰ) Compositions and calcination conditions of alloy extrudates

ZHAO Huiji, BAI Rui, SHANG Hongyan, XU Yongqiang, YIN Changlong, ZHAO Ruiyu, LIU Chenguang

2005, 56(8): 1492-1497.

Abstract ( 689 )

PDF (1907KB) ( 275 )

Related Articles | Metrics

A novel activated fixed-bed Raney nickel catalyst for hydrogenation of unsaturated organic compounds was prepared by extruding the Ni-Al alloy powder with pseudoboehmite as binding material, calcining the extrudates in air at a high temperature and leaching out the aluminum with caustic solution.The effects of binding material contents and calcination conditions (calcination temperature and calcination time) on catalyst properties and catalytic activity were studied with TG-DTA,XRD,BET,SEM analyses and model reaction of benzene hydrogenation.The experimental results showed that the recommended pseudo-boehmite contents was 20%, and that the novel fixed-bed Raney nickel catalyst might acquire lower resultant α-Al₂O₃ content, higher particle compressive strength and higher benzene hydrogenation activity by calcining the alloy extrudates at 860 ℃ for 1—2 h in air.SEM and BET results showed that the catalysts possessed abundant porous structures.

Novel fixed-bed Raney nickel catalysts(Ⅱ) Leaching procedures of alloy extrudates

ZHAO Huiji, BAI Rui, XU Yongqiang, SHANG Hongyan, ZHAO Ruiyu, YIN Changlong, LIU Chenguang

2005, 56(8): 1498-1503.

Abstract ( 783 )

PDF (456KB) ( 244 )

Related Articles | Metrics

A novel activated fixed-bed Raney nickel catalyst was prepared by extruding Ni-Al alloy powder with 20% pseudo-boehmite as binding material. Appropriate leaching conditions of calcined alloy extrudates were studied by using of benzene hydrogenation activity as the main evaluation factor.Leaching procedures of such calcined alloy extrudates were also tested by contrast with alloy powder,in which released hydrogen and dissolved aluminum in caustic solution were determined.The experimental results showed that the fixed-bed Raney nickel catalyst could achieve higher benzene hydrogenation activity by leaching the alloy extrudates calcined at 860℃ for 2 h with 10%—20% NaOH solution at 80—90℃ for 3—4 h, and that the leaching procedures had significant effect on catalyst compressive strength. The metallic aluminum in calcined alloy extrudates could almost dissolve completely in caustic solution within 1—4 h, and microporous structures appeared on the surface of leached catalysts appear. The results of benzene hydrogenation suggested that the novel fixed-bed Raney nickel catalysts showed higher hydrogenation activity and stability, and that benzene could be hydrogenated to cyclohexane completely at mild conditions of reaction temperature 120 ℃, hydrogen pressure 0.5 MPa and space velocity 2 h^-1.

Reaction/crystallization/distillation coupling model for PX oxidation process

WANG Lijun;LI Xi;WANG Qinbo;ZHANG Hongjian

2005, 56(8): 1504-1510.

Abstract ( 759 )

PDF (522KB) ( 365 )

Related Articles | Metrics

p-Xylene oxidation is a complicated gas-liquid-solid three phases process, involving such physical and chemical phenomena as reaction,absorption, distillation and crystallization,etc.A complete reactor model was built to take into account reaction/distillation/crystallization coupling effects.The related basic model parameters were computed based on reaction kinetics,phase equilibria, transport model and crystallization dynamics. The proposed model was solved by the Newton-Raphson method.The model was verified by comparison with commercial unit data and was proved to be enough to simulate the existing commercial units.On the basis of the model, the effects of temperature,residence time and feed mixture ratio and distillation plate number for the oxidation process was further investigated.The simulation results provided directions and means to improve existing units.

Development of naphtha dry point soft sensor by adaptive partial least square regression

YAN Xuefeng;YU Juan;QIAN Feng

2005, 56(8): 1511-1515.

Abstract ( 753 )

PDF (675KB) ( 517 )

Related Articles | Metrics

A novel adapting partial least square regression (APLSR) approach was proposed to develop the naphtha dry point soft sensor of the primary distillation tower.Many operation conditions were related to naphtha dry point and there existed a significant correlation among them.In order to obtain a naphtha dry point soft sensor with high predicting correctness, the different predicting contribution ratios of modeling samples were taken into account by APLSR and the optimal number of the latent variables was obtained according to the predicting ability of the soft sensor.When APLSR was used for the predicting sample, each modeling sample was weighted according to its ratio of predicting contribution for the predicting sample and satisfactory results were obtained.Further, the previous analysis value of the naphtha dry point was regarded as a new independent variable for the soft sensor and the predicting correctness of the soft sensor was enhanced remarkably.

Discussion about dynamic soft-sensing modeling

MA Yong;HUANG Dexian;JIN Yihui

2005, 56(8): 1516-1519.

Abstract ( 694 )

PDF (388KB) ( 675 )

Related Articles | Metrics

After more than ten years of development, great achievements of soft-sensing technology have been made not only in theory but also in practice.Up until now, however, most research work in the soft-sensing field have been essentially concentrated on static soft-sensing models.The relations and distinctions between dynamic soft-sensing models and static soft-sensing models are discussed. Using the impulse response model, a dynamic soft-sensing method based on least squares is developed. Some improvements to the method are also presented. A simulation example is given to validate the effectiveness of the method and its improvements.

Simulation on rule of shrinkage of large CPUE based on neural network

JIANG Kaiyu;SU Tongyi;WANG Minjie;YU Tongmin

2005, 56(8): 1520-1525.

Abstract ( 641 )

PDF (443KB) ( 319 )

Related Articles | Metrics

The selection of shrinkage is one of the critical factors in successful design for large casting polyurethane elastomer(CPUE) mold.Based on experiments, the influence of process parameters on shrinkage of large CPUE products was systematically studied.The structural model of the products and the neutral network based on BP were estabilished.Through the learning of experimental data,the neutral network model could be used to predict the shrinkage of large CPUE by taking the process parameters as input and product shinkage as output.The comparison of prediction results and experiment data indicated that the shrinkage of CPUE at different process parameters could be predicted.Thus the number of mold repairing and production cost could be reduced.

Anodic polarization behavior of carbon steel in Na₂CO₃-NaHCO₃ solution

ZHAO Jingmao;ZUO Yu

2005, 56(8): 1526-1529.

Abstract ( 734 )

PDF (845KB) ( 297 )

Related Articles | Metrics

The anodic polarization curves of mild steel were measured potentiodynamically in sodium carbonate solution containing different concentrations of sodium bicarbonate, and the surface products of steel were analyzed with XPS. The potentiodynamical studies showed two anodic peaks and two passive zones present in all the polarization curves. Compared to those obtained in NaHCO₃ solutions, the first passive zones of the polarization curves in Na₂CO₃-NaHCO₃ solutions became wider and clearer. Both of the potentials at two peaks shifted to positive direction after adding bicarbonate in carbonate solution, which meaned bicarbonate ions could weaken the passivation of iron in carbonate solutions. A good linear relationship was found between the potential at the second peak and the logarithm of the concentration of bicarbonate ions. According to the electrochemical thermodynamics of iron in Na₂CO₃-NaHCO₃ solution, the following reaction might take place at the second peak:3FeCO₃+4H₂O---Fe₃O₄+3HCO^-₃+5H⁺+2e.The results with XPS showed that the iron surface consisted mainly of ferrous and ferric oxides, which further supported the above reaction.

Effect of aggregated protein on membrane fouling process

ZHAN Jin;LIU Zheng

2005, 56(8): 1530-1535.

Abstract ( 765 )

PDF (1105KB) ( 643 )

Related Articles | Metrics

Bovine serum albumin (BSA) forms dimer or oligomer in its aqueous solution, which has a significant effect on its chromatographic behavior and the adsorption of BSA on membrane surface.The experimental results obtained by the present study demonstrated the formation of BSA aggregate via intermolecular disulfide bonds. Addition of low concentration of DTT (dithiothreitol)effectively reduced the formation of BSA aggregate, and thus enhanced the filtration process. Modification of membrane by acrylic acid showed that electrostatic interaction also played an important role in the membrane fouling caused by BSA adsorption.The results described above provided important insights into the physical and chemical interactions governing membrane fouling by protein adsorption, which might inspire new approaches to reducing membrane fouling.

Synthesis of etodolac

DAI Liyan;WANG Xiaozhong;CHEN Yingqi

2005, 56(8): 1536-1540.

Abstract ( 1712 )

PDF (469KB) ( 1081 )

Related Articles | Metrics

Synthesis of etodolac,a non-steroidal anti-inflammatory agent, was studied.In the study o-nitroethylbenzene as raw material was reduced by Fe / hydrochloric acid.The intermediate o-ethylaniline could be diazotized and reduced by sodium sulfite to give o-ethylphenylhydrazine,and 7-ethyltryptophol was obtained by condensation of o-ethylphenylhydrazine and 2,3-dihydrofuran in isobutanol as solvent.Finally 7-ethyltryptophol without separation reacted with methyl 3-oxopentanoate and was hydrolyzed to give the title compound.The optimal reaction conditions(temperature, time,molar yield) were as follows.Reduction of nitro group：reflux，3 h，96.2%;diazotization：0 ℃，0.5 h;reduction of diazonium salt：70—75 ℃，3 h，92.5%(two steps);synthesis of 7-ethyltryptophol：reflux，3 h;preparation of etodolac methyl ester：0 ℃，1.5 h，63.0%(two steps);hydrolysis：reflux，2.5 h，95.0%.The structures of etodolac and its methyl ester were the same as those reported in literature.

Refolding of denatured carbonic anhydrase assisted by amide and refolding kinetics

LU Chenxing;XIAO Qingmin;DONG Xiaoyan

2005, 56(8): 1541-1546.

Abstract ( 663 )

PDF (484KB) ( 156 )

Related Articles | Metrics

The effect of various amides on the refolding of denatured carbonic anhydrase B (CAB) was investigated at low guanidine hydrochloride (GdmCl) concentration.The competitive model of first-order folding and third-order aggregation was found to well describe the dynamic refolding process in the presence of the additives. The results indicated that the denatured CAB could be properly refolded in the presence of the amides, and the effect of the amides on assisting CAB refolding was found kinetically similar to that of GdmCl. The refolding rate constant k_N decreased with increasing additive concentration, while there was an optimum additive concentration where a minimum aggregation rate constant k_A was obtained. At this additive concentration, the value of the ratio of k_N to k_A was maximum, leading to the maximal refolding yield of CAB.

Preparation of monodispersed calcium alginate gel beads in high voltage electrostatic field

QU Beibei, YU Weiting, LIU Xiudong, BAO Decai, SONG Xiaoyan, QI Wentao, MA Xiaojun

2005, 56(8): 1547-1551.

Abstract ( 654 )

PDF (604KB) ( 277 )

Related Articles | Metrics

In this paper, the effect of operation parameters on the monodispersity of calcium-alginate gel beads prepared in high-voltage electrostatic field were analyzed.The parameters included the applied potential (U)，the distribution of electrostatic field, the frequency and the flow rate of solution through the capillary. Furthermore, the process is analyzed with the theory of jet break-up in electrostatic field. The result showed that the modified symmetrical electrostatic field was more advantageous in preparing the monodispersed gel beads than the traditional method. Meanwhile,gel beads with good monodispersity(CV<20%) and stability without aggregation were produced under a range of applied potential (U), frequency and flow rate of solution through the capillary.

Electrochemical treatment of simulated anthraquinone dye wastewater with in situ electrogenerated active chlorine at constant potential

YANG Yunzhe, YANG Weishen, YANG Fenglin, ZHANG Xingwen

2005, 56(8): 1552-1558.

Abstract ( 768 )

PDF (2320KB) ( 400 )

Related Articles | Metrics

The electrochemical oxidation of C.I.Reactive Blue 19 with in situ electrogenerated active chlorine was carried out in a divided flow-by cell using metallic oxide coatings as anode.At a constant potential,measurements of the absorbance at 592 nm and 255 nm were used to follow the discoloration of the dye and degradation of its aromatic ring.The experimental results suggested that the discoloration and degradation were strongly affected by electrode potential,initial pH,concentration of dye and NaCl,while slightly affected by supporting electrolyte concentration and temperature.After 4 h electrolysis at an electrode potential of 1.13 V(vs SCE), for a simulated wastewater composed of 0.5 mol•L^-1 NaCl, 0.1 mol•L^-1 Na₂SO₄, 0.1 mmol•L^-1 dye, the diseoloration of the dye and degradation efficiencies of its aromatic ring were 100%,ca.40%,respectively,while no obvious change of TOC was observed. Indirect electrooxidation by using electrogenerated active chlorine was predominant in the electrochemical oxidation.

Effects of humidifying level of cathode and anode gas on mass transfer in PEMFC

HE Guangli, DING Xinwei, YOU Hongxin, ABUDULA Abuliti

2005, 56(8): 1559-1564.

Abstract ( 817 )

PDF (1151KB) ( 356 )

Related Articles | Metrics

A two-dimensional model of PEMFC with conventional flow field was established and the partial differential equations were solved based on the control-volume method. The effects of humidifying level on membrane conductivity and mass transfer were investigated.The numerical results indicated that total water drag coefficient increased when humidification in anode increased, and membrane conductivity was largely improved when humidification in anode was enhanced.Total water drag coefficient reduced when humidifying level in cathode increased.Humidification in anode was more important than that in cathode where the humidification effect was limited only to relatively low current density.The anode gas should be humidified as much as possible,when PEMFC operated at low current density.It is advisable to decrease the humidifying level of anode gas when operating at high current density to avoid two-phase flow in cathode so as to improve mass transfer.

Anoxic biological phosphorus removal and effect of excessive aeration on biological phosphorus removal in A²O process

WANG Xiaolian, WANG Shuying, MA Yong, PENG Yongzhen

2005, 56(8): 1565-1570.

Abstract ( 796 )

PDF (1273KB) ( 812 )

Related Articles | Metrics

A pilot-scale nutrient removal activated sludge system, based on the A²O configuration, was used to treat brewery wastewater.In the experiment, the existence of denitrifying phosphorus removing bacteria (DPB) and the contribution of DPB to phosphorus removal was observed.The tests showed the average total amount of anoxic P uptake accounted for 70% of the total amount of P uptake of the system at steady state, oxygen requirement could be decreased significantly(about 25%).Denitrifying phosphate removal resolved the competition for organic substrates between Poly-P organisms and denitrifiers under lower organic loading.Effluent total-P concentration could achieve less than 0.30 mg•L^-1 and average effluent total-N was less than 10 mg•L^-1.It is clearly demonstrated that the phosphorus uptake almost stopped in an over-aerated system, the released phosphorus could not be taken up fully again.Consequently, incomplete phosphorus uptake led to temporary reduction of biological phosphorous removal efficiency.It took about the time of one sludge age to eliminate that disturbance.

Co-pyrolysis of waste tires and biomass under plasma condition

CAO Qing, LV Yongkang, ZHU Suyu, XIE Kechang

2005, 56(8): 1571-1574.

Abstract ( 665 )

PDF (728KB) ( 586 )

Related Articles | Metrics

The gaseous products of co-pyrolysis of waste tires and biomass under DC arc plasma condition were investigated.The results showed that the volumetric concentration of acetylene in carbon-containing gases obtained when waste tires, biomass and coal were separately pyrolyzed was 14.6%,13.7% and 10.6% respectively when the parameters experimental run were 150 A of electric current, 310 V of voltage,2.0 m³•h^-1 of flux of argon, 0.65 m³•h^-1 of flux of main hydrogen, 0.4 m³•h^-1 of flux of auxiliary hydrogen and 5.0×10^-4kg•s^-1 of feed rate.Under the same condition, the volumetric concentration of acetylene in carbon-containing gases produced from the mixtures of biomass and waste tires when the mass ratio of biomass and waste tire was 1/2 increased obviously,nearly 2—3 times that of tires or biomass pyrolyzed separately.The concentration of acetylene was closely related to the volatile matter and the amount of oxygen.In addition, the possible mechanism of the pyrolysis occurred under plasma condition was proposed.

Penetrating properties of novel organic-inorganic hybrid nanocapsules

NI Kefan;SHAN Guorong;WENG Zhixue

2005, 56(8): 1575-1579.

Abstract ( 596 )

PDF (848KB) ( 207 )

Related Articles | Metrics

A novel organic-inorganic hybrid nanocapsule was synthesized by mini-emulsion copolymerization of styrene and 3-trimethoxysilyl propyl methacrylate (MPS) on the well dispersed octane droplet templates.The morphology was characterized by transmission electron microscopy(TEM) and atom force microscopy(AFM).The microstructure parameters were characterized by gas adsorption instrument.The wall of the capsules was found to have microporous structures.According to these characteristics, a penetration model was established by using the percolation theory.The penetration diffusion coefficient was dependent on porosity and tortuosity.The kinetics of the penetration process was studied with ultraviolet-spectrophotometer and diffusion coefficient and tortuosity were calculated.Diffusion velocity increased with the increase of MPS content in capsules due to larger porosity;tortuosity was less in the cresol red-methanol system than in the anthracene-tetrahydrofuran system; and tortuosity nearly did not change with the MPS content in capsules. All these results were consistent with the percolation theory. The loading of the anthracene was also proved by infrared spectrometry, and the release diffusion coefficient was much smaller than that of loading, but did not change with the MPS content in capsules.

Controlling elementary reaction of bulk ring-opening copolymerization of octamethylcyclotetrasiloxane with N-β-aminoethyl-γ-aminopropylmethyldimethyoxysilane

LUO Zhenghong, CAO Zhikai, ZHAN Xiaoli, CHEN Fengqiu, YANG Yongrong

2005, 56(8): 1580-1584.

Abstract ( 751 )

PDF (669KB) ( 168 )

Related Articles | Metrics

The bulk ring-opening copolymerization mechanism of octamethylcyclotetrasiloxane (D₄) with N-β-aminoethyl-γ-aminopropylmethyldimethyoxysilane (APAEDMS) and its key controlling elementary reactions were firstly investigated and demonstrated by means of the Monte Carlo method in this paper.With consideration of the cost of computation as well as the precision of simulated results, a new computational model was developed to simulate the reaction system based on the free volume theory and the chemical reaction kinetic theory.The intrinsic reaction rate constants were obtained by simulating the main elementary reactions of copolymerization. This paper indicates from microscopic level: (1) The bulk copolymerization mechanism of D₄ with APAEDMS is an anion chain-reaction mechanism with the characteristics of the step polymerization.(2) The chain-condensation reaction and its reversible reaction are the key controlling elementary reactions of the copolymerization mechanism for the studied system,while the chain initiation elementary reactions are not the key controlling elementary reactions of the copolymerization mechanism for the studied system.

Synthesis of monodisperse crosslinked St-PEG200DMAcopolymeric microspheres

WANG Juan;LIANG Tongxiang;YAN Yinghui

2005, 56(8): 1585-1589.

Abstract ( 710 )

PDF (2110KB) ( 293 )

Related Articles | Metrics

Dispersion copolymerization of styrene with polyethelyene glycol 200-dimethacrylae as crosslinking agent was carried out by using poly (N-vinylpy rrolidone), 2,2-azo-bisisobutyronitrile as the stabilizer and initiator, respectively. Highly monodisperse microspheres were prepared by the one-step method of dispersion copolymerization.The effects of the concentration of crosslinking agent on the microsphere morphology and copolymerization rate were studied.It was found that the crosslinking agent played an important role on the particle morphology and system stability.When the concentration of crosslinking agent was below 2.0%(mass) of styrene, all the microspheres were spherical with smooth surface. However, after the concentration reached 2.5%(mass) or higher, monodisperse microspheres with flower-liked wrinkles on the surface were obtained.

Preparation and characterization of ternary Pb-Sn-Cd alloy nanoparticles

CHEN Hongjie, LI Zhiwei, WU Zhishen, ZHANG Zhijun

2005, 56(8): 1590-1593.

Abstract ( 712 )

PDF (1097KB) ( 236 )

Related Articles | Metrics

Ternary Pb-Sn-Cd alloy nanoparticles were prepared by the sonochemical dispersion method. The nanoparticles were found to be about 40—60 nm and coated with an amorphous layer of surfactant dioctadecyldithiophosphate(DDP).The formation and constituent of the as-prepared nanoalloy were characterized by transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), differential thermal analysis and thermogravimetry (DTA-TG), and Fourier transform infrared (FT-IR) spectrophotometer.It was also found that the powder showed excellent antiwear property by tribological test results.