The Marangoni effect induced by mass transfer at the interface between two immiscible liquids displays important influence on laboratory and industrial operation of solvent extraction. A systematic numerical study of the two-dimensional Marangoni effect in a two liquid layer system was conducted. The linear relationship of the interfacial tension versus the solute concentration was incorporated into a mathematical model accounting for liquid flow and mass transfer in both phases. The typical cases analyzed by Sternling & Scriven (AIChE J., 1959) using the linear instability theory were simulated by the finite difference method and good agreement between the theory and the numerical simulation was observed. The simulation suggests that the Marangoni convection needs certain time to develop sufficiently in strength and scale to enhance the interphase mass transfer, the Marangoni effect is dynamic and transient, and remains at some stabilized level as long as the mass transfer driving force is kept constant. When certain level of shear is imposed at the interface as in most cases of practical significance, the Maran-goni effect is suppressed slightly but progressively as the shear is increased gradually. The present two-dimensional simulation of the Marangoni effect provides some insight into the underlying mechanism and also the basis for further theoretical study of the three-dimensional Marangoni effect in the real world and in chemical engineering applications.

Slug initiation and subsequent evolution along a 5.0 cm ID,16m long horizontal pipe are experimentally studied.The transient characteristics of interfacial structures are described by using simultaneous measurements of the liquid height at multiple locations along the pipe.Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated.It is found that the slug is initiated by a deterministic process with replenishment and depletion of liquid near the inlet for the superficial gas velocity U_SG<3.0 m·s^-1 and by a stochastic process with wave coalescence along the pipe for U_SG>3.0 m·s^-1.The evolution of the slugs is strongly affected by superficial gas and liquid velocities for U_SG<3.0 m·s^-1 but weakly affected by the superficial gas velocity for U_SG>3.0 m·s^-1.The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging,with slugs forming postponed further downstream.The slug frequency at the outlet is,however,not affected by the variation in the pressure oscillation.

The investigation on bubble behavior in electric field helps to analyze the mechanism of electric enhancement of boiling heat transfer. Experiments were performed to investigate the bubble deformation in direct current (DC) electric field with bubbles attached to the orifice. The air bubbles were slowly generated in the transformer oil pool at different orifices, so that the effect of flow on bubble shape was eliminated. The results showed that the bubbles were elongated and the departure volume decreased when the electric field was intensified. The major and minor axes, aspect ratio and departure volume increased with increasing the orifice diameter. Both the electric field and orifice size have great influence on bubble behavior. The bubble deformation was also simulated to compare with the experimental results. The numerical and experimental data qualitatively agree with each other.

The segregated flow pattern, which occurs in a 26.1 mm diameter, horizontal, stainless steel test section, is investigated. Pressure gradient and in situ phase distribution data were obtained for different combinations of phase superficial velocities ranging from 0.05 m·s^-1 to 0.96 m·s^-1. For the current small Eötvös number liquid-liquid system (E_oD=4.77), the dominant effect of interfacial tension and wall-wetting properties of the liquids over the gravity is considered. The approach introduces the closure relationship for the case of turbulent flow in a rough pipe, and attempts to modify the two-fluid model to account for the curved interface. In present flow rates range, wave amplitudes were found small, while interfacial mixing was observed. An adjustable definition for hydraulic diameters of two fluids and interfacial friction factor is adopted. The predicted pressure gradient and in situ phase distri-bution data have been compared with present experimental data and those reported in the literature.

The kinematical characteristics and thermophoretic deposition of inhalable particles with the diameters of 0-2.5μm (hereafter referred to as PM2.5) suspended in turbulent air flow in a rectangular duct with temperature distribution were experimentally studied. Particle dynamics analyzer (PDA) was used for the on-line measurement of particle motion and particle concentration distribution in the cross-sections of the duct. The influences of the parameters such as the ratio of the bulk air temperature to the cold wall temperature and the air flow rate in the duct on the kinematical characteristics and the deposition efficiencies of PM2.5 were investigated. The experimental results show that the deposition efficiencies of PM2.5 mainly depend on the temperature difference between the air and the cold wall, while the air flow rate and the particle concentration almost affect hardly the deposition efficiency. The radial force thermophoresis to push PM2.5 to the cold wall is found the key factor for PM2.5 deposition. Based on the experimental results, an empirical modified Romay correlation for the calculation of thermophoretic deposition efficiency of PM2.5 is presented. The empirical correlation agrees reasonably well with the experimental data.

Effect of configuration(structure of electrode,interelectrode gap,positions of inlet and outlet,volume of the cell and additional nets)on mass transfer characteristic of a filter-press type electrochemical cell has been studied.The mass transfer coefficients on the electrodes were obtained by using the well-known technique based on the determination of limiting diffusion current.It is found that mass transfer coefficients with mesh electrode are greater than that of with plate electrode.Mass transfer coefficient is decreased with interelectrode gap.While interelectrode gap achieved a certain value(7 mm),mass transfer coefficient is steady,no more declining.Mass transfer characteristic for different positions of inlet and outlet are different and dimensionless number groups correlated equations are obtained by experiment.Mass transfer characteristic is the best when inlet located on the top and outlet on the bottom of the cell respectively.While magnified the volume of the cell to eight times,mass transfer characteristic changes little.Mass transfer characteristic without nets is lower than that of with additional nets in the exit region,but higher than that of with additional nets in the entry region.

The adsorption of dibenzofuran(DBF)on three commercial granular activated carbons(GAC)was investigated to correlate the adsorption equilibrium and kinetics with the morphological characteristics of activated carbons.Breakthrough experiment was conducted to determine the isotherm and kinetics of dibenzofuran on the activated carbons.All the experiment runs were performed in a fixed bed with a process temperature of 368 K.The effects of adsorbent morphological properties on the kinetics of the adsorption process were studied.The equilibrium data are found satisfactory fitted to the Langmuir isotherm.An intraparticle diffusion model based on the obtained Langmuir isotherm was developed for predicting the fixed bed adsorption of dibenzofuran.The result indicated that this model fit all the breakthrough curves well.The surface diffusion coefficients of dibenzofuran on the activated carbon are calculated,and a relationship with the microporosity is found.As it was expected,the dibenzofuran molecule finds more kinetic restrictions for the diffusion in those carbons with narrower pore diameter.

N,O-carboxymethyl chitosan(NOCC)composite nanofiltration(NF)membranes were prepared by coating and cross-linking.The fermentation effluent from a wine factory was treated with the resulting NOCC/polysulfone(PSF)composite NF membranes.The permeate flux and the removal efficiencies of the resulting NF membranes for the color,chemical oxygen demand(COD_Cr),total organic carbon(TOC),and conductivity of the fermentation effluent were investigated in relation to the driving pressure,the feed flow,and the operation time.The permeate flux and the removal efficiencies were found to increase with the increase of the driving pressure or the feed flow.At 0.40 MPa and ambient temperature the removal efficiencies were 95.5%,70.7%,72.6%, and 31.6%for color,COD_Cr,TOC,and conductivity,respectively.The membrane was found to be stable over a 10h operation for the fermentation effluent treatment.

Cake filtration has been widely used in many chemical processes with more non-Newtonian,highly viscous and compressible materials involved.Neither traditional nor modern filtration theory can be applied in practice."Equivalent cake filtration model"is a recently developed mathematical model to describe cake filtration for both Newtonian and non-Newtonian fluids,in either steady or unsteady filtration stages.This model has two strengths:(1)It can be used to determine equivalent capillary radii and predict filtration quality based on the properties of solid/liquid system and operation parameters;and(2)to calculate cake specific resistance and its variations with time at various cake thickness locations.

The oxidation of polyunsaturated fatty acids(PUFA)in emulsion with stirring and limited oxygen compensation was studied.A mathematical model of diffusion-oxidation was developed considering the mass transfer resistance of a gasliquid boundary,the resistance of the boundary layer from the emulsifier membrane,and the autocatalytictype autoxidation reaction of PUFA.The dynamic mass transfer coefficient of the emulsifier membrane,k₀,was introduced.The model was verified by comparing the predictions of the model with the experimental data.The results indicated that the model was in good agreement with the oxygen diffusion and linoleic acid oxidation in the emulsion,and showed good applicability in the prediction of the effect of the emulsifier type on the oxidation of PUFA in the emulsion.It indicated that the oxidation of PUFA in emulsions,with stirring and limited oxygen compensation from the atmosphere,was controlled mostly by mass transfer resistance from the emulsifier membrane.

The support of catalyst for the direct synthesis of diphenyl carbonate(DPC)by heterogeneous catalytic reaction was prepared by the sol-gel method.Compared with activated charcoal,molecular sieve,porous ceramics, hopcalite,the support prepared by the sol-gel method has higher activity.The characterization of the support by X-ray diffraction(XRD)and transmission electron microscope(TEM)show that the main crystal phase is Co₂MnO₄ and the average particle diameter is about 40 nm.The optimum conditions for synthesis of the support were determined by orthogonal experiments,which indicate that the proportion of Cu,Mn,and Co is the first important factor influencing the yield and selectivity of DPC.Temperature of calcination is the second one.The optimum conditions are:molar proportion of Cu,Mn,and Co being 1:1:1,temperature of calcination 700℃,drying at 100℃,temperature of water bath 85℃.The yield and selectivity of DPC in the process can reach 38% and 99% in the batch operation,respectively.The copper cobalt manganese mixed oxides chosen as the support contribute more to the high catalytic activity than the sol-gel method.

Differential evolution(DE)is an evolutionary optimization method,which has been successfully used in many practical cases.However,DE involves large computation time,especially,when used to optimize the computationally expensive objective function.To overcome this difficulty,the concept of immunity based on vaccination is used to help proliferate excellent schemata and to restrain the degenerate phenomenon.To improve the effectiveness of vaccines,a new vaccine autonomous obtaining method,and a method of deciding the probability of vaccination are proposed.In addition,a method for modifying the search space dynamically is proposed to enhance the possibility of converging to the true global optimum.Experiments showed that the improved DE performs better than the classical DE significantly.

A batch-to-batch optimal iterative learning control(ILC)strategy for the tracking control of product quality in batch processes is presented.The linear time-varying perturbation(LTVP)model is built for product quality around the nominal trajectories.To address problems of model-plant mismatches,model prediction errors in the previous batch run are added to the model predictions for the current batch run.Then tracking error transition models can be built,and the ILC law with direct error feedback is explicitly obtained.A rigorous theorem is proposed,to prove the convergence of tracking error under ILC.The proposed methodology is illustrated on a typical batch reactor and the results show that the performance of trajectory tracking is gradually improved by the ILC.

Production planning under uncertainty is considered as one of the most important problems in plant-wide optimization.In this article,first,a stochastic programming model with uniform distribution assumption is developed for refinery production planning under demand uncertainty,and then a hybrid programming model incorporating the linear programming model with the stochastic programming one by a weight factor is proposed. Subsequently,piecewise linear approximation functions are derived and applied to solve the hybrid programming model under uniform distribution assumption.Case studies show that the linear approximation algorithm is effective to solve the hybrid programming model,along with an error≤0.5% when the deviation/mean≤20%.The simulation results indicate that the hybrid programming model with an appropriate weight factor(0.1-0.2)can effectively improve the optimal operational strategies under demand uncertainty,achieving higher profit than the lin-ear programming model and the stochastic programming one with about 1.5% and 0.4% enhancement,respectively.

A new apparatus was designed with a thick-walled glass capillary,electric heater tube with red copper and heat preservation.The thick-walled glass capillary was used for its advantages of resistance to acid corrosion and pressure,and ease of observation.The experimental densities over the entire range of mole fraction for the binary mixture of p-xylene+acetic acid and o-xylene+acetic acid were measured using the new apparatus at temperatures ranging from 313.15K to 473.15K and pressure ranging from 0.20 to 2.0 MPa.The density values were used in the determination of excess molar volumes,V^E.The Redlich-Kister equation was used to fit the excess molar volume values,and the coefficients and estimate of the standard error values were presented.The experimental results prove that the density measurement apparatus is successful.

Viscosities and densities for 1-butyl-3-methylimidazolium hexafluorophosphate([C₄mim][PF₆])+N,N-dimethylformamide(DMF)binary mixtures have been measured at the temperature range from 293.15 K to 318.15 K.It is shown that the viscosities and densities decrease monotonously with temperature and the content of DMF.Various correlation methods including Arrhenius-like equation,Seddon et al.'s equation,Redlich-Kister equation with four parameters,and other empirical equations were applied to evaluate these experimental data.A model based on an equation of state for estimating the viscosity of mixtures containing ionic liquids were proposed by coupling with the excess Gibbs free energy model of viscosity,which can synchronously calculate the viscosity and the molar volume.The results show that the model gives a deviation of 8.29% for the viscosity,and a deviation of 1.05% for the molar volume when only one temperature-independent adjustable parameter is adopted.The correlation accuracy is further improved when two parameters or one temperature-dependent parameter is used.

The production of acrylates from biomass-originated lactic acid is of extraordinary importance,to overcome the increasing worldwide shortage of petroleum.In this study,the catalytic dehydration of methyl lactate over a calcium sulfate catalyst,with various promoters,has been carried out to identify potential catalyst/promoter com-binations for acrylate production.The best catalyst for methyl acrylate formation in this study has been calcium sulfate,with cupric sulfate and phosphates as promoters.The optimal mass ratio of m(CaSO₄):m(CuSO₄):m(Na₂HPO₄):m(KH₂PO₄)is 150.0:13.8:2.5:1.2.Effects of carrier gas,reaction temperature,feed concentration as well as contact time on the dehydration of methyl lactate have been investigated.With nitrogen as a carrier gas,a combined yield of acrylic acid and methyl acrylate is 63.9% from 60%(by mass)methyl lactate at 400℃ with 7.7 seconds contact time.

The textural properties of acid-activated bentonite(AAB),which were prepared using four different concentrations of sulfuric acid,were analyzed by adsorption-desorption isotherm of nitrogen using an automated specific surface area and porosity analyzer.The total pore volume,specific surface area and average pore diameter of these four kinds of AAB show a regular changing trend,increasing first and then decreasing,the optimum of which can be achieved at a sulfuric acid concentration of 25%(sample A25).The kinetic analysis of the adsorption of β-carotene and chlorophyll in model oil solutions,namely,xylene and edible oil solution,has been investigated by using AAB.Experimental results indicated that the adsorption data fit the pseudo-second-order model well.The whole adsorption process of the two pigments on AAB was divided basically into two parts:the initial adsorption of pigments was rapid in the first 10 min,followed by a slower adsorption process till equilibrium was attained at 60 min.In addition,the amount and rate of adsorption on A25 increase synchronously with the initial pigment concentration and temperature.The results showed that the adsorption kinetics behavior of AAB with respect to the pigments is not influence by the xylene and edible oil solution.

A new Thiele's modulus,φ_F,was developed to provide a gradual transition between zero and the first order of kinetics,and to accurately calculate the mass transfer flux and the effectiveness factor for the Monod biofilm.Values of the effectiveness factor,calculated using the new Thiele's modulus,were compared with those obtained from numerical solutions and from other published moduli and empirical formulae.The comparison indicated that the new Thiele's modulus was the best modulus for the Monod biofilm model.In addition,another Thiele's modulus,φ_G,was developed for a Monod biofilm,covered with an external water layer.The overall effectiveness factor can also be calculated by using both moduli φ_F and φ_G.The criteria that were proposed for identification were based on the values of φ_F andφ_G,the limiting processes for biomass growth,and substrate conversion. Developed from φ_F,a new parameterψwas related uniquely to such features as the depth and shallowness of the generalized substrate concentration profiles inside a Monod biofilm.Criteria were developed to identify the types of concentration distribution inside a Monod biofilm.These methods were used to estimate the substrate flux and the concentration distribution of the biofilms defined in the first benchmark problem(BM1),by a task group of the International Water Association on Biofilm Modeling.

The microemulsified acid system composed by diesel oil,hydrochloric acid and emulsifier was investigated in this paper.The stability of microemulsified acid and the phase behavior of the microemulsified system were studied.The size distribution and the corrosion inhibition performance were also observed.The results showed that the diesel oil microemulsified acid system possessed small size and good stability under different temperature. The tolerance to CaCl₂ reached 80 g·L^-1. Compared with the same concentration hydrochloric acid solution,the corrosion inhibition performance of the diesel oil microemulsified acid system was remarkable.

Computational fluid dynamics(CFD)combined with detailed chemical kinetics was employed to model the filtration combustion of a mixture of methane/air in a packed bed of uniform 3 mm diameter alumina spherical particles.The standard k-ε turbulence model and a methane oxidation mechanism with 23 species and 39 elemental reactions were used.Various equivalence ratios(1.47,1.88,2.12 and 2.35)were studied.The numerical results showed good agreement with the experimental data.For ultra-rich mixtures,the combustion temperature exceeds the adiabatic value by hundreds of centigrade degrees.Syngas(hydrogen and carbon monoxide)can be obtained up to a mole fraction of 23%.The numerical results also showed that the combination of CFD with detailed chemical kinetics gives good performance for modeling the pseudo-homogeneous flames of methane in porous media.

The corrosion behaviors of simulated archaeological iron in solution(0.06 mol·L^-1 NaCl+0.03 mol·L^-1 Na₂SO₄+0.01 mol·L^-1 NaHCO₃)simulating soil water composition was investigated by potentialdynamic polariza-tion,constant potential polarization,and simulated occluded cell(O.C.)galvanostatic tests.X-ray diffraction(XRD), energy dispersive spectrometry(EDS),and scanning electron microscope(SEM)were used to study the corrosion morphology and the evolution of corrosion product.The objective was to discover the transformation process of archaeological iron,and determine the distribution of chlorinated corrosion products.The results showed that the presence of crevice,cavities,and channels facilitates the localized corrosion under rusts;the autocatalytic effect in-creases the concentration of Fe²⁺,Cl^-,and SO₄^2-,and promotes local acidification within the crevices and cavities. Meanwhile,the phase transformation of corrosion products is concluded to proceed by means of two ways.One is that the ferrous ions are transformed into different kinds of FeOOH via the intermediate Fe(II)-Fe(III)hydroxyl-salt (i.e.Green Rusts);the other is that the Fe²⁺ ions are transformed into FeCl₂,FeCl₃,and orange powders akaganeite at the crevices and cavities.

The experimental study was carried out to optimize the nozzle shape and dimension for the pulse clean-ing of a ceramic filter candle.A bench scale unit of ceramic filter consisting of four commercial filter elements was used to measure the traces of the transient pressure around the nozzle and the overpressure in the filter cavity during the pulse-jet injection of pulse gas.Overpressure in the filter cavity is related to the pulse cleaning force.Nozzle design is concerned to increase the overpressure at the open end of filter element of pulse cleaning inlet,as well as to minimize the consumption of pulse gas.Convergent nozzle induces more secondary flow and generates higher pulse cleaning effect than straight nozzle.Nozzles of different convergent ratio(ratio of outlet to inlet diameter of nozzle)by changing the convergent angle and height were tested.The outlet diameter of convergent nozzle seri-ously influences the cleaning effect.The optimum convergent ratio increases with the increase of pulse gas pressure. The nozzle position(distance of nozzle tip from the open end of filter inlet)is also important to decide the nozzle dimension.Nozzle of large outlet diameter accepts high pressure of pulse gas to provide large overpressure in the filter cavity of top position by applying long distance.

The effects of strain and chloride concentration on pitting susceptibility for type 304 stainless steel were studied in situ using the electrochemical technology under constant strain.The impact factor f_ε was brought forward to value the effect of strain on pitting.The pitting behaviors of type 304 stainless steel in various chloride concentrations under the strain levels 0%,10%,and 30%were investigated.Potentiostatic polarization technology was used to study how the chloride concentration affected corrosion current density.The results indicated that f_ε increased substantially and pitting potential varied remarkably when chloride concentration was over 90 mg·L^-1. Un-der the three levels of strain mentioned above,when chloride concentration was below 463 mg·L^-1,121 mg·L^-1,and 98 mg·L^-1,respectively,the pitting potential shifted towards positivity and,the passive film became more stable. When the strain was below 10%,the pitting susceptibility of type 304 stainless steel varied greatly as strain increased,whereas the susceptibility only changed a little when the strain was over 10%

The performance of a Venturi tube used in wet gas flow have been explored mainly under higher-pressure condition,but very often,low-pressure test exists in some oil and gas fields in Tianjin Dagang Oil and Gas Field in China.In this study,the performance of horizontally mounted Venturi meters in low-pressure wet gas flow is discussed.Three 50 mm Venturi meters were tested systematically,withβvalues of 0.4048,0.55 and 0.70,the operation pressure of 0.15 MPa,0.20 MPa,0.25 MPa,the gas densiometric Froude number from 0.6 to 2.0,the modified Lockhart-Maretinelli parameter from 0.0022 to 0.06,and the ratio of the gas liquid mass flow rate from 0.5 to 0.99. The effects of modified Lockhart-Maretinelli parameter,pressure,gas densiometric Froude number,diameter ratio, and gas-liquid mass flow rate ratio to the Venturi tube are analyzed with new independent data.Furthermore, low-pressure performance was compared with that under high pressure.

The monodispersed Co nanoparticles were successfully prepared by means of hydrogen plasma method in inert atmosphere.The particle size,specific surface area,crystal structure and morphology of the samples were characterized by transmission electron microscopy(TEM),BET equation,X-ray diffraction(XRD),and the corre-sponding selected area electron diffraction(SAED).The catalytic effect of Co nanoparticles on the decomposition of ammonium perchlorate(AP)was investigated by differential thermal analyzer(DTA).Compared with the ther-mal decomposition of pure AP,the addition of Co nanoparticles(2%-10%,by mass)decreases the decomposition temperature of AP by 145.01-155.72℃.Compared with Co₃O₄ nanoparticles and microsized Co particles,the catalytic effect of Co nanoparticles for AP is stronger.Such effect is attributed to the large specific surface area and its interaction of Co with decomposition intermediate gases.The present work provides useful information for the application of Co nanoparticles in the AP-based propellant.

Energy recovery device(ERD)is an important part of the seawater reverse osmosis(SWRO)desalination system.There are principally two kinds of ERDs,the centrifugal type and the positive displacement(PD)type. The PD type is of extensive concern and is preferred in large-scale plants.In this article,an innovative fluid switcher was presented and a two-cylinder hydraulic energy recovery unit with a labscale fluid switcher was set up. Tap water was used as the working medium instead of the actual seawater and brine in SWRO desalination plants. Under steady state operating conditions,the experimental results were obtained on the variations of the pressure and flow rate to and from the energy recovery unit.The hydraulic recovery efficiency(E_H)of the energy recovery unit with the fluid switcher reached up to 76.83%.