A collocated finite volume method on unstructured meshes is introduced to simulate the viscoelastic flow of the polymer melt with viscous dissipation past a confined cylinder.The constitutive equation for the simulations is non-isothermal FENE-P model,which is derived from the molecular theories.The temperature effect on the macroscopic fields(e.g.,velocity,stress) and microscopic fields(e.g.,molecular orientation,deformation,stretch) is investigated by comparison of isothermal and non-isothermal situations.This investigation indicates that temperature rise caused by viscous dissipation should not be neglected since it has significant effect on the macroscopic and microscopic properties of the polymer melt.

A thermal model for a heat pipe with axially swallow-tailed microgrooves is developed and analyzed numerically to predict the heat transfer capacity and total thermal resistance.The effect of heat load on the axial distribution of capillary radius,and the effect of working temperature and wick structure on the maximum heat transfer capability,as well as the effect of the heat load and working temperature on the total thermal resistance are all investigated and discussed.It is indicated that the meniscus radius increases non-linearly and slowly at the evaporator and adiabatic section along the axial direction,while increasing drastically at the beginning of the condenser section.The pressure difference in the vapor phase along the axial direction is much smaller than that in the liquid phase.In addition,the heat transfer capacity is deeply affected by the working temperature and the size of the wick.A groove wick structure with a wider groove base width and higher groove depth can enhance the heat transfer capability.The effect of the working temperature on the total thermal resistance is insignificant;however,the total thermal resistance shows dependence upon the heat load.In addition,the accuracy of the model is also verified by the experiment in this paper.

A mass transfer model for devolatilization process of highly viscous media in rotating packed bed(RPB) was developed based on penetration theory and mass conservation.Before establishing the model,some mass transfer experiments of thin film were conducted in a designed diffusion cell including vacuum and feeding system. In this study,acetone was used as the volatile organic compound(VOC) and syrup as the highly viscous media.The thickness of thin film was changed by using different liquid distributor.It was found that bubbling played an important role in the devolatilization.The correlation of diffusion coefficient of acetone in highly viscous dilute solution was proposed.The relative error between predicted and experimental data was within the range of ± 30% for diffusion coefficient of acetone in syrup.A comparison of experimental data of RPB with model indicated that the relative error was within ± 30% for efficiency of acetone removal.

Capture of CO₂ by hydrate is one of the attractive technologies for reducing greenhouse effect.The primary challenges are the large energy consumption,low hydrate formation rate and separation efficiency.This work presents a new method for capture of CO₂ from simulated flue gasCO₂(16.60%,by mole)/N₂ binary mixture by formation of cyclopentane(CP) hydrates at initial temperature of 8.1℃ with the feed pressures from 2.49 to 3.95 MPa.The effect of cyclopentane and cyclopentane/water emulsion on the hydrate formation rate and CO₂ separation efficiency was studied in a 1000 ml stirred reactor.The results showed the hydrate formation rate could be increased remarkably with cyclopentane/water emulsion.CO₂ could be enriched to 43.97%(by mole) and 35.29%(by mole) from simulated flue gas with cyclopentane and cyclopentane/water(O/W) emulsion,respectively,by one stage hydrate separation under low feed pressure.CO₂ separation factor with cyclopentane was 6.18,higher than that with cyclopentane/water emulsion(4.01), in the range of the feed pressure.The results demonstrated that cyclopentane/water emulsion is a good additive for efficient hydrate capture of CO₂.

Hydrophilic poly(vinyl butyral)(PVB)/Pluronic F127(F127) blend hollow fiber membranes were prepared via thermally induced phase separation(TIPS), and the effects of blend composition on the performance of hydrophilic PVB/F127 blend hollow fiber membrane were investigated.The addition of F127 to PVB/polyethylene glycol(PEG) system decreases the cloud point temperature,while the cloud point temperature increases slightly with the addition of F127 to 20%(by mass) PVB/F127/PEG200 system when the concentration of F127 is not higher than 5%(by mass) .Light scattering results show that the initial inter-phase periodic distance formed from the phase separation of 20%(by mass) PVB/F127/PEG200 system decreases with the addition of F127,so does the growth rate during cooling process.The blend hollow fiber membrane prepared at air-gap 5mm,of which the water permeability increases and the rejection changes little with the increase of F127 concentration.For the membrane prepared at zero air-gap,both water permeability and rejection of the PVB/F127 blend membrane are greater than those of PVB membrane,while the tensile strength changes little.Elementary analysis shows that most F127 in the polymer solution can firmly exist in the polymer matrix,increasing the hydrophilicity of the blend membrane prepared at air-gap of 5mm.

A one-dimensional unsteady heterogeneous parallel mass transfer(ODUHPMT) model was developed for the absorption enhancement of volatile organic compounds(VOC) by the dispersed droplets.An analytical solution for enhancement factor was obtained based on surface renewal theory and the Laplace domain transformation. The absorption rate of propane into water at different stirring speeds with the added micro dodecane droplets was investigated experimentally in a thermostatic stirred tank.The mass transfer flux across the gas-liquid interface and the enhancement factor were measured.The results showed that the dodecane has an obvious enhancement effect on propane absorption into water,the maximum enhancement factor reached 11.The enhancement factor increased with increasing dodecane volume fraction and decreased with increasing stirring speed.The experiment data agreed well with the model predictions and showed high prediction accuracy of ODUHPMT model.

A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO₂ in flue gas by carbon adsorbents for flue gas purification.The change in adsorption capacity and adsorption rate with time at different water vapor concentrations and different SO₂ concentrations was studied.The model was in good agreement with experimental data.The surface reaction was probably the rate controlling step in the early stage for SO₂ adsorption by ZL50 activated carbon.The parameters m and n in the nth order adsorption kinetic model were related to the magnitude of the time compensation and adsorption driving force,respectively.The change of parameter n with water vapor concentrations and sulfur dioxide concentrations was studied and some physical implications were given.The sum of square errors was less than 1.0 and the average absolute percentage deviations ranged from 0.5 to 3.2.The kinetic model was compared with other models in the literature.

The carbonaceous adsorbent was prepared from mixtures of dewatered sludge and sawdust with enhanced ZnCl₂ chemical activation.Characteristics of the adsorbent were studied using scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), and adsorption of nitrogen.The surface analysis showed that the carbonaceous adsorbent had good specific surface and porosity(394 m 2·g^-1 of BET surface,0.12 and 0.10 ml·g^-1 of microporous and mesoporous volume,respectively) .The oxygen functional groups such as-OH,C-O and C=O were found on the surface by FTIR and XPS(X-ray photoelectron spectroscopy) .The adsorption of elemental mercury(Hg0) on the carbonaceous adsorbent was studied in a fixed bed reactor.The dynamic adsorption capacity of carbonaceous adsorbent increased with influent mercury concentration,from 23.6μg·g^-1 at 12.58μg·m^-3to 87.9μg·g^-1 at 72.50μg·m^-3,and decreased as the adsorption temperature increased,from 246 μg·g^-1 at 25℃ to 61.3μg·g^-1 at 140℃,when dry nitrogen was used as the carrier gas.The carbonaceous adsorbent presented higher dynamic adsorption capacity than activated carbon,which was 81.2μg·g^-1 and 53.8μg·g^-1 respectively.The adsorption data were fitted to the Langmuir adsorption model.The physical and chemical adsorption were identified on the adsorbent.

A new feeding mode for a simulated moving bed(SMB) is proposed.The outlet stream from zone Ⅱ is collected at regular intervals.The concentration of the solution is increased by dissolving raw materials and then fed to zone Ⅲ as the feed stream during the next collection interval.In this feeding mode,the concentration of the stream fed to zone Ⅲ is identical to that of original feed,while in a conventional SMB,the feed is diluted by mix-ing with the outlet stream of zone Ⅱ before feeding to zone III.The new feeding mode increases the inlet concentra-tion of zone Ⅲ.A modeling investigation shows that higher inlet concentration of zone Ⅲ increases the height of concentration band in SMB,improving the separation performance significantly.In comparison with the traditonal feeding mode,the new feeding mode increases the productivity by 23.52% and decreases the solvent consumption by 22.56%,so as to increase the raffinate and extract concentrations by 53.17% and 20.38%,respectively.The col-lection interval for the outlet stream from zone Ⅱ has no effect on the separation performance after reaching the steady state,so that the collection interval can be increased to make the operation more convenient.

Absorption of NO_x into nitric acid solutions was studied in the presence of ozone by using a rotating packed bed(RPB) contactor.The influences of operating parameters,such as high gravity number,amount of ozone,gas velocity,liquid spray density and inlet concentration of NO_x,on the removal efficiency of NO_x were investigated,among which the high gravity number and ozone amount are more important.Ozone was introduced to oxidize HNO₂ to HNO₃ to prevent the decomposition of HNO₂ in the liquid phase.The high gravity number presents the effective external force for enhancing the mass transfer of ozone from gas phase to liquid phase.Under the experimental condition,the removal efficiency of NO_x is higher than 90%and the concentration of nitric acid product exceeds 45%.

A mixing-precipitation model based on the modified coalescence-redispersion model was presented to describe the flow,mixing,nucleation and growth in a rotating packed bed(RPB).The model was coupled with population balance,mass balance and crystallization kinetics.It predicted well the influence of coalescence prob-ability,which represents the mixing intensity among droplets,on the particle number density,supersaturation and mean particle size of the produced precipitates.The effects of the radial thickness of packing,liquid flow rate and rotating speed on the product particle size were also investigated.The results indicate that the needed radial length of packing is short for sparingly soluble substance precipitation(about 40-50 mm in this work), and the mean parti-cle size of precipitates decreases with the increase of rotating speed and liquid flow rate,respectively.The validity of this model was verified by experiment on BaSO₄ precipitation in RPB.

On-line estimation of unmeasurable biological variables is important in fermentation processes,directly influencing the optimal control performance of the fermentation system as well as the quality and yield of the targeted product.In this study,a novel strategy for state estimation of fed-batch fermentation process is proposed.By combining a simple and reliable mechanistic dynamic model with the sample-based regressive measurement model,a state space model is developed.An improved algorithm,swarm energy conservation particle swarm optimization(SECPSO), is presented for the parameter identification in the mechanistic model,and the support vector machines(SVM) method is adopted to establish the nonlinear measurement model.The unscented Kalman filter(UKF) is designed for the state space model to reduce the disturbances of the noises in the fermentation process.The proposed on-line estimation method is demonstrated by the simulation experiments of a penicillin fed-batch fermentation process.

In the past 30 years,signed directed graph(SDG), one of the qualitative simulation technologies,has been widely applied for chemical fault diagnosis.However,SDG based fault diagnosis,as any other qualitative method,has poor diagnostic resolution.In this paper,a new method that combines SDG with qualitative trend analysis(QTA) is presented to improve the resolution.In the method,a bidirectional inference algorithm based on assumption and verification is used to find all the possible fault causes and their corresponding consistent paths in the SDG model.Then an improved QTA algorithm is used to extract and analyze the trends of nodes on the consis-tent paths found in the previous step.New consistency rules based on qualitative trends are used to find the real causes from the candidate causes.The resolution can be improved.This method combines the completeness feature of SDG with the good diagnostic resolution feature of QTA.The implementation of SDG-QTA based fault diagno-sis is done using the integrated SDG modeling,inference and post-processing software platform.Its application is illustrated on an atmospheric distillation tower unit of a simulation platform.The result shows its good applicability and efficiency.

In this paper,a multi-loop internal model control(IMC) scheme in conjunction with feed-forward strategy based on the dynamic partial least squares(DyPLS) framework is proposed.Unlike the traditional methods to decouple multi-input multi-output(MIMO) systems,the DyPLS framework automatically decomposes the MIMO process into a multi-loop system in the PLS subspace in the modeling stage.The dynamic filters with identical structure are used to build the dynamic PLS model,which retains the orthogonality among the latent variables.To address the model mismatch problem,an off-line least squares method is applied to obtain a set of optimal filter parameters in each latent space.Without losing the merits of model-based control,a simple and easy-tuned IMC structure is readily carried over to the dynamic PLS control framework.In addition,by projecting the measurable disturbance into the latent subspace,a multi-loop feed-forward control is yielded to achieve better performance for disturbance rejection.Simulation results of a distillation column are used to further demonstrate this new strategy outperforms conventional control schemes in servo behavior and disturbance rejection.

An extended liquid-liquid equilibrium(LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam.In this model,caprolactam is introduced as a new group.New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data.The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium,including quaternary systems containing the mixed solvent of an alcohol and an alkane.The model can be applied to predict caprolactam solubility in water and benzene accurately.Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model.Satisfactory prediction results are obtained.

An experimental device was set up to study the hydrate formation conditions.Effects of pore size,salinity,and gas composition on the formation and dissociation of hydrates were investigated.The result indicates that the induction time for the formation of hydrates in porous media is shorter than that in pure water.The decrease in pore size,by decreasing the size of glass beads,increases the equilibrium pressure when the salinity and temperature are kept constant.In addition,higher salinity causes higher equilibrium pressure when the pore size and temperature are kept constant.It is found that the effects of pore size and salinity on the hydrate equilibrium are quite different.At lower methane concentration,the hydrate equilibrium is achieved at lower pressure and higher temperature.

In our previous work,we calculated transport properties of pure gaseous polyatomic carbon tetrafluoride(CF4) and five equimolar binary gas mixtures of CF₄ with noble gases through inversion technique.The present work is a continuation of our studies on determining the transport properties of binary gas mixtures CF₄ with some gases including three diatomic molecules CO,N₂,and O₂,a linear polyatomic CO₂,and two non-linear polyatomic molecules SF₆ and CH₄.The Chapman-Enskog and Vesovic-Wakeham methods as well as inversion procedure are used to determine the viscosities,diffusivities,and thermal conductivities,which deviates from the literature values within 1%,4%,and 5%,respectively.

Density,ultrasonic velocity and viscosity of imidazolinone derivatives are studied in dimethyl formamide(DMF) at 308.15 K.From the experimental data,various acoustical parameters,such as specific impedance Z,isentropic compressibility k_s,Rao's molar sound function R_m,van der Waals constant b,relaxation strength r,intermolecular free length L_f,internal pressure π,solvation number S_n,relative association R_A,etc.are evaluated,which helps in understanding the molecular interactions occurring in these solutions.

Isothiocyanates(ITCs) extracts were prepared from fresh broccoli.Their antioxidant properties were evaluated by using the in vitro bioassays,including superoxide anion radical(O₂^-), hydroxyl radical(HO^-) and 2,2-diphenyl-1-picrylhydracyl(DPPH·) radical-scavenging methods,lipid peroxidation assay,and reducing power assay.The ITCs extracts exhibited significant dose-dependent antioxidant activities(P<0.01) .Its antioxidant-stability was affected by temperature and storage condition,although it was more stable than vitamin C(Vc) .GC-MS iden-tified sulforaphane in the ITCs extracts.The antioxidant activity of sulforaphane was approximately one tenth to one fifth of that of Vc.Sulforaphane was experimented to be one of dominating contributors to antioxidant capacity of ITCs extracts.However,there was no direct antioxidant activity found for benzyl isothiocyanate(BITC) in vitro. Therefore,it could be concluded that the general group(-N=C=S) was not the essential part for the antioxidant activity of sulforaphane.It is suggested that the ITCs extracts from broccoli can be developed into a promising food additive for healthy food.

The inexpensive and moisture-stable Lewis-acidic ionic liquids were prepared and applied for transesterification of soybean oil to biodiesel.The influences of molar ratio of methanol to soybean oil,reaction temperature and amount of ionic liquids were investigated.The transesterification of soybean oil to biodiesel catalyzed by choline chloride·xZnCl₂ ionic liquids showed many advantages such as mild conditions and lower cost.On the other hand,the non-ideal yield and complicated separation between biodiesel and soybean oil were also investigated and analyzed.The improvement on the systems of choline chloride·xZnCl₂ was proposed for further investigation.

Apatite-lanthanum silicate has attracted considerable interest in recent years due to its high oxide ion conductivity.In this paper,V-doped samples La_10-xV_x(SiO₄)₆O_3+x(0≤x≤1.5) were prepared by sol-gel method and the influences of V-dopant content on calcining temperature and conductivity were reported.The samples were characterized by thermal analysis(TG-DSC), X-ray diffraction(XRD) and scanning electron micrograph(SEM) . The apatite was obtained at 800℃,a relatively low temperature in comparison to 1500℃ with the conventional solid-state method.The ceramic pellets sintered at 1200℃ for 5 h showed a higher relative density than La_9.33Si₆O₂₆ pellets sintered at 1400℃ for 20 h.The conductivities of samples were measured by electrochemical impedance spectroscopy.The conductivity was improved with the increase of V-dopant content on La site.

In this paper a polyaluminum chloride solution with high Al₁₃ content was prepared and used as raw material for preparation of γ-Al₂O₃₃·H₂O and NaOH had little effect on the alumina sample formation.The impurities of NH₄Cl and NaCl in solution can be removed through repeated washing by EDX analysis.Calcination temperature had a significant effect on alumina crystal phase.The alumina sample can transform completely toγ-Al₂O₃ in the subsequent heating from 600℃ to 800℃.It is very interesting that Al₁₃ can be existed inγ-Al₂O₃ phase even after calcinations.The results indicate that polyaluminum chloride with high Al₁₃ content is an effective material to prepareγ-Al₂O₃.

The inhibiting effect of ciprofloxacin,norfloxacin and ofloxacin on the corrosion of mild steel in 1 mol·L^-1 HCl and the mechanism were studied at different temperatures using mass loss measurement,electrochemical method,and X-ray photoelectron spectroscopy(XPS) .Effective inhibition was shown by mass loss,potentiodynamic polarization and impedance spectroscopy measurement.The corrosion rate of the metal in the mass loss measurement,and the corrosion reaction on cathode and anode in the electrochemical measurement were accelerated when temperature was increased.XPS results showed that the inhibitors adsorbed effectively on the metal surface.

The extraction ability of organophosphorus extractant D2EHPA(di-2-ethylhexyl phosphoric acid) and hydroximic extractant Lix984N are investigated by the extraction equilibrium experiments.Effects of carrier concen-tration and organic/aqueous volume ratio on the mass transfer of hollow fiber renewal liquid membrane(HFRLM) are studied.Results show that,in the extracting process,kerosene and n-heptane are more suitable than methyl-isobutyl ketone,butylacetate and benzene as the diluents of D2EHPA or Lix984N.The favorable feed pH is 4.4 for D2EHPA and 2.6 for Lix984N.The mass transfer flux of HFRLM increases with carrier concentration and finally reaches a plateau.The mass transfer flux and the overall transfer coefficient increase with the organic/aqueous volume ratio,reach the maximum and then decrease.

A laboratory reactor was designed to test the effect of the interference instant of HY on the pyrolysis of pubescens.The time instant for intermediate species from pyrolysis to contact HY was controlled by varying the position of the catalyst bed relative to the pyrolytic cell.It was found that the effect of the interference instant was significant on the variation of different intermediate species,and the yield and quality of the products.The results also showed that,with the increase in the distance between the pyrolytic cell and the catalyst bed,the yield of liquid and relative content of the organics such as aldehyde,phenols,etc.,decreased,while the yield of residue and relative content of acetic acid increased.The deoxygenation of the intermediate species was favored when the catalyst exerted its performance on them immediately after their formation.