In this paper, the ionic hydration of five ions Li~+, Na~+, K~+, F~-, Cl~- is investigated by molecular dynamics simulation at 298.15K. A clear microscopic configuration of ions in aqueous solution is obtained. The cations are surrounded by water molecules with oxygen atoms approaching them, while the anions are surrounded by water molecules with hydrogen atoms approaching them. A new hydration factor is proposed to quanti tativelycharacterize the strength of ionic hydration. The order of hydration strength for cations is Li~+>Na~+>K~+, whereas for anions F~->Cl~-. For Li~+, although there is a second coordination shell, no second hydration shell exists. These are valuable information for further establishment of molecular thermodynamic models for electrolyte solutions.

The NVT ensemble Monte Carlo method is used for the simulation of aqueous solutions of benzene in supercritical conditions for obtaining microscopic structures and the radial distribution functions(RDFs). The simple point charge(SPC) model and the LJ model with the optimized parameters by liquid simulations (OPLS) are adopted for the description of interactions between water and benzene molecules, respectively, in which the long range correction of Ewald is considered. RDFs for 10 cases are obtained to explain the behavior of benzene molecules changing from hydrophobic to hydrophilic,that takes place in the supercritical conditions. The effects of the variables, including temperature, concentration and density, on the microstructures of the aqueous sol-utionsare investigated. As a result, an appropriate condition for benzene molecules dissolving homogeneously in supercritical water is recommended.

In this paper, an experiment is conducted to investigate the effects of oscillation on transient and time average heat transfer characteristics for fully developed turbulent flow in a uniformly heated helical coiled tube. The phase lag of transient coefficient of local heat transfer relative to the phase feature of flow rate oscillations is also studied. The experimental range of parameters is as follows: Re=25000～125000, oscillations frequency f=0.05～0.003, which corresponds to the thermal hydrodynamic oscillations encountered in a helical coiled tube boiling channel. A correlation for predicting the time-averaged heat transfer coefficient of single-phase turbulent flow under unsteady or oscillatory condition is proposed. The secondary flow mechanisms and the effects of interaction between the flow rate oscillation and secondary flow are analyzed on the basis of experimented data. Some new phenomena are observed and explained.

On a new experimental set-up of filter with three ceramic filter elements, the transient velocity outside the filter element is measured by hot-wire anemometer during pulse-jet cleaning process. The influences of reservoir pressure and pulse duration on instantaneous velocity are investigated. The experimental results show that there exists a remarkable back-flow between the pulse-jet cleaning and normal filtration process. It is shown that the pulse-jet cleaning velocity and back-flow velocity increase with rising reservoir pressure. The back-flow velocity peak is several times of filtration velocity and makes fine particles redeposit on the filter element surface and even penetrate the filter element wall.

Experiments were conducted in a riser of 186 mm ID and 9 m height. The different flow patterns, including turbulent, fast and pneumatic fluidized beds, were obtained by changing the superficial gas velocity from 0.95 to 10.0 m·s~-1. An optical fiber density probe was used to measure local transient signals at different radii and at different axial cross-sections for each flow regime in order to show the varied flow structures both in the axial and radial directions. Deterministic chaos theory was used to analyze the time series and consequently Kolmogorov entropy was calculated to describe the dynamic characteristics of signals. The results showed that the local Kolmogorov entropy can describe the flow structure of gas/solids two phase flow in different regimes. At the same time the entropy was strongly related with the local solids fraction in three types of flow regimes: when 1-ε is greater than 0.05, the K_mlkeeps almost constant; when 1-ε is smaller than 0.05, the K_mlincreasesdramatically with the decrease of 1-ε. This implies that the solids fraction is a dominant factor that influences the turbulent structure of two-phase flow.

Based on the theoretical analysis on a growing bubble,a technique for measuring surface dilational viscosity is proposed. The growing process of the bubble is captured by videoimage technique. An edge-tracing algorithm using a local threshold and a method for profile optimization are used applied to determine the shape of the growing bubble. A device for measuring the dynamic surface tension from the profile of a growing bubble is set up,so that the dynamic surface tension can be determined directly as a function of time. The surface dilational viscosity of the solutions is determined through the rate of change of dynamic surface tension with respect to the rate of surface expansion. The surface dilational viscosity of sodium dodecyl sulfate (SDS) solution is measured. The data and those with different rates of surface deformation from the literature indicate that the surface exhibits surface reological property.

The close relationship between activity coefficient and internal pressure is noticed. The van Laars theory is modified by substituting the internal pressure of van der waals fluid with Franks relation. An excess Gibbs free energy equation which is very similar to Wohls equation is derived and the famous van Laar equation, solubility parameter equation, Margules equation and Scatchard-Hamer equation etc. are all its special examples. The corresponding activity coefficient equation is established by further taking account of the contribution of excess entropy. It was proved that this equation is general, namely it is applicable not only to various small molecular liquid mixtures, but also to various polymer solutions, and has more extensive applicability than local-composition activity coefficient equations. In addition, a new definition of solubility parameter, which is more generalized than that proposed by Hildebrand, is obtained from this Gibbs free energy model.

On the basis of Pitzer model(1973), ionic strength is introduced to express the interaction parametersbetween two kinds of electrolyte and those between electrolyte and non-electrolyte at a high temperature of 100 ℃.The solubilities of H_3BO_3-Na_2SO_4-NaCl-H_2O system at 25 ℃ and 100 ℃ are calculated,the calculated values agree with experimental results well. With this quarternary system phase diagram, the technology of producingboric acid from natural borax ore in Xizang China is discussed.

The protection of immobilized cellulase by trehalose during drying and storage is investigated. It is found that trehalose can reduce the activity losts of immobilized cellulase efficiently during its drying, and the mass ratio of trehalose and enzyme is about 0.25 at 58 ℃. The stability of immobilized cellulase increases with increase of trehalose or decrease of storage temperature. By mean of infrared spectrometry and DSC, the mechanismof protection of immobilized cellulase by trehalose is studied. Increase of stability of immobilized enzymes is not only because of the interaction between trehalose and enzyme, but also because of the formation of a glassy state in and around enzyme moleculars, especially near active sites of enzymes, so that the structure of enzymes is restricted, and activities of enzyme can be preserved at a high temperature.

The technological characteristics of pretreatment in purification process of antibiotic fermentation broth are studied in this paper.The effects of some factors on filtration rate and on concentration are discussed.Spiramycin (SPM) and Penicillin (Pn)are studied in details as examples. It is discovered in the experimentsthat the concentration of SPM or Pn in the filtrate varied with the pH value. The concentration reaches a maximum when pH=5.5.At the same time, a solution equilibrium of protein is present. The protein will denature on the condition of excess acid or base, and its concentration in solution reaches a minimum when pH=6.0—6.5. There is also an adsorption equilibrium of SPM on protein precipitate and other solids.The recoveryof filtrate is influenced by many extraneous materials because of rivalry between them.A rational explanationis given by application of modified Langmuir adsorption theory based on the experimental results.The theoretical model is developed and mathematical formulas are derived.

In this paper the intrinsic kinetics of TS-1 catalyzed epoxidation of propylene with hydrogen peroxide inmethanol/water is studied. The kinetic reaction is carried out in a semi-batch stirred-tank reactor at T=303.15～333.15 K,p=0.4～0.7 MPa.Four models from proposed mechanisms are regressed.The results obtainedshow that the Eley-Rideal mechanism fits the experimental data best.The Eley-Rideal mechanism Supported by the National Natural Science Foundation of China(No.29792070). To whom correspondence should be addressed.proposes that hydrogen peroxide molecule adsorbs on the catalytic sites and reacts with dissociated propylene molecule, and surface reaction is the rate-controlling step.Propylene oxide and propylene can also adsorb on the catalytic sites and compete with hydrogen peroxide, which hindes the epoxidation.Then, it is advisable to take propylene oxide out of the reactor to improve the reaction rate of epoxidation and prevent the side reaction of propylene oxide with the solvent(methanol).The adsorption of solvent methanol and water on the catalytic sites is complete under the reaction condition, so it does not affect the epoxidation rate.After parameter estimation and model discrimination, a rational model, which gives a good agreement with the experimental data, is obtained.The average relative deviation between experimental and calculated reaction rates is 12.5 %.roposesthathydrogenperox

Pervaporation is unique among membrane separations, involving a change of phase to achieve separation. Its most potential application is the use of pervaporation process to drive an equilibrated reaction, such as esterification, etherification, synthesis of methyl isobutyl ketone. In a membrane reactor, pervaporation has been applied to the continuous removal of water from esterification reaction mixture. For a special reaction system, if the kinetic model is established,the relationship between reagent conversion, product yield and water concentration can all be described by it at the same time. It can provide the theoretical basis for process economic evaluation,defining the optimum reaction conditions and for predicting the reaction system status. For the esterification coupled pervaporation membrane reactor, many studies have been done concerning the coupled membrane process kinetic model. But, some important factors, such as reaction-separation temperature and feed water concentration which are always unavoidable in industries were not taken into consideration in these kinetic models. On the other hand,a standard method for defining water permeance has not been established yet. So, in these studies, the established kinetic models can only simulate the coupled membrane process under limited conditions. In this study, pervaporation separation of ethanol-water azeotropic mixture and the experiments of pervaporation coupled esterification are carried out in a batch reactor with the membrane area of 19.2 cm~2. PPVA/PAN composite membrane is prepared and used in the coupled membrane reactor. Through combining the kinetic equation of esterification and the kinetic equation of pervaporation, a kinetic model for esterification-pervaporation coupled composite membrane process is established:dXdt=n_0kV-1.8×10~-5n_0 (X-Y)(1-X)(R_1-X)-XK(Y+R_2) dYdt=dXdt-pS(X+R_2)V-1.8×10~-5n_0 (X-Y)exp-E_aRT All the factors that may influence the shift of esterification chemical equilibrium are all taken into consideration in this kinetic model. At the same time, the method for defining the modeling parameter, p, is determined. The above equations can be solved numerically by using a personal computer and the Runge-Kutta method to yield the concentrations of different species in the reactor under different reaction conditions and times. The studying results showed that the experimental data and the simulation data obtained from the same reaction condition are in good agreement. Therefore we can be concluded that the established kinetic model of pervaporation-esterification coupled composite membrane reactor can predict the reaction-separation process exactly.

Traditional optimization strategy for crude distillation units is generally based on the feasible path method,which has low optimizing efficiency because of complexity of distillation model.Direct infeasible path method for the units has very high dimensions which cause difficulty in converging.According to the properties of crude distillation model,an IOIPO(Inside-Out Infeasible Path Optimization) algorithm is proposed by combining of inside-out simulation method of distillation column and infeasible path method of optimization.In this algorithm,residual equations of energy balance converge within optimization layer,which means simulation convergence in each optimization is not required,meanwhile in optimization layer only a few constraint equations are added in,so that the IOIPO method can greatly raise converging speed and reduce computational time.It will be very useful for on-line optimization of crude distillation units.

Many synthesis problems of chemical processes are attributed to combinatorial optimization problems which are diffcult to solve. Line-up Competition Algorithm (LCA) presented in part Ⅰ is applied to the structural and parameter optimization for process synthesis in this paper. The expression of competition driving force and the algorithmic framework are given for solving combinatorial optimization problems. The wto principles of determining mutation adjacent regions are proposed which are helpful to balance local search and global search. The algorithm is applied to the optimization of a large scale pressure relief header network and a heat exchanger network synthesis problem,respectively, and the results show that LCA algorithm can discover a very good near-optimum solution after examining an extremely small fraction of possible solutions. The solution is superior to those obtained with simulated annealing algorithms and genetic algorithms in literature. Examples demonstrate that LCA algorithm has great potential for solving combinatorial optimization problems.

In the present paper a theoretical description of thermal explosion (spontaneous ignition),which occurs in exothermically reacting systems, in provided. The steady-state criterion for thermal explosion to occur is described. By means of perturbation theory, functional forms are analysed for the most generalized circumstances in which the Biot number (Bi) is arbitrary and in which the reaction rate is generally represented by f (θ).Asymptotic solutions are derived for the limit of large activation energies where the dimensionless activation energy ε is small (i.e.ε0).Corresponding critical values for the Frank-Kamenetskii parameters, reduced reaction rate, δ and reduced central temperature-excess,θ_0 given by using these asymptotic equations, are used for obtaining critical temperatures T_m and T_0,cr,where T_m is critical ignition temperature and T_0,cris the critical (maximum ) central temperature, for some typical samples. These results are provided in Tables 5 and 6.

Numerical analyses are conducted for combined free and forced laminar convection in the thermal entrance region of inclined pipes with buoyancy-aided flow. The effects of buoyancy force, pipe inclination angle and axial conduction on the hydrodynamic and heat transfer characteristics are investigated, and numerical res-ults of velocity and temperature profiles, distributions of the Nusselt numbers and wall shear stress are obtained. The velocity and temperature profiles are distorted and become asymmetric, and a reverse flow occurs near the pipe top as the buoyancy effect becomes significant. The wall shear stress varies from minimum at the top pipe wall to maximum at the bottom pipe wall. The axial conduction effect becomes significant at low Pe number. The circumferential average Nusselt number reaches a maximum at an inclination angle between 25° and 45° for Pe=71 but the maximum appears at α=90° for Pe=2.5.

In this paper an experimental research on the oil-water liquid-liquid two-phase flow patterns and their transitions in both horizontal and vertical helically coiled tubes is presented. The different flow patterns are defined and distinguished from each other according to the relationship between oil and water phase in the tubes. The flow pattern maps and phase inversion points are obtained and compared with the results in horizontal pipes. The effect of the dimensions and different locations of the helically coiled tubes on flow pattern transition and phase inversion point is also examined.

A method of measuring the critical temperature and pressure of thermally unstable compounds was developed,in which a thick wall borosilicate glass tube was used as sample tube,and a coated quartz glass was Supported by the Tianjin Natural Science Foundation(No.973602911). To whom correspondence should be addressed.used as heater. The advantage of the measuring apparatus was that a small amount of sample was sufficient to determine the critical properties accurately,a very short time was needed to heat the sample,and the fluid of interest could be uniformly heated. Taking n-pentane,n-hexane and 1-heptene as standard reagents,the reliability of the apparatus was checked by measuring the critical temperatures and critical pressures of these three compounds. Critical temperatures and pressures of 4 substances including dipropyl ether,allyl amine,isoamyl nitrite ester,and dimethylsulfide were measured. The low residence time (<20 s) at elevated temperature minimized decomposition and other reactions,making it possible to measure the critical properties of many unstable fluids. Except for dimethylsulfide,all data were determined for the first time.

By suspension cultivating of Lithospermum erythrorhizon and determining the dynamic curves, a structural kinetic model was established. By using the equation sets including 14 parameters and 9 state variables,the changes of excellular carbon source, intracellular carbon source, intracellular structural components,intracellular intermediate,cell respiration loss and intra/extracellular products were discussed. The model parameters were estimated by the Runge-Kutta method and the nonlinear Powell method. The sensitivity analysis was done. The simulation results could fit the real curves quite well. It was the first time to use a structural model to describe the suspension culture dynamics of Lithospermum erythrorhizon cells. The structural model was also the foundation for further study.

Based on Onsager and Onsager-Fuoss-Chen equations of conductance,a new prediction equation is proposed for dilute electrolyte solution. It is used to predict and calculate the conductance of some single strong electrolyte solutions and their mixtures at 298.15 K. The results show good agreements with those data from literatureand they are better than those calculated with Onsager limiting equation and two-parameter Onsager-Fuoss-Chen equation. In addition,the new equation can also be used to determine the limiting molar conductivityof strong electrolyte by one-point experimental data of the molar conductivityat a certain concentration.The calculation deviation of the new equation shows a minimum value when the strength of ion in solution approaches 0.001 mol·dm~-3,hence,so long as the molar conductivity near this point is measured,the limitingmolar conductivity can be calculated conveniently and reliably by the new equation.

The formation of the barrier layer of anodic porous alumina film has been investigated in phosphoric acid solution. The results show that with the increase of phosphoric acid concentration,the time needed to form barrier layer is shortened,and also the barrier layer becomes thinner. The phenomenon can be interpreted reasonablyby the stress concentration that developed in barrier layer.

Single-phase flow patterns generated by axial impeller are investigated by 3D Particle Dynamic Analyzer. Mean flow and turbulence intensities are measured for the impeller zone and the bulk regions. The effect of D/T and blade tip angle on flow pattern is studied as well. The measured results show that the flow in impeller zone oscillates periodically at the frequency of blade sweep. The flow patterns generated by different ratios of impeller diameter to tank diameter impeller are approximately the same below impellers,but a small second recirculation loop is formed in the upper part of vessel at the ratio of impeller diameter to tank diameter D/T=0.35.

By using the developed gas-particle two-phase flow-reaction model,the simulation of particle dynamicswas carried out in a commercial riser in FCC. The results show clearly that the catalysts backflow seriously in the nozzle zone by the influence of shoot and congregate in the pipe center. In the upper part of the riser reactor,catalysts flow in a fully developed steady current and the radial distribution of particle concentration gradually becomes what happens in vertical tubes,because the influence of shoot is more and more weakened. It is easy to find out that shoot influences the hydrodynamics of particle-phase intensively.

In this paper,the slip phenomenon(negative slip phenomenon) of coal-water mixture flowing in pipes is proved by the method of combining theoretical analyses with experimental investigations for the first time. On the basis of analyzing the mechanism of slip flow phenomenon,a real rheological model of coal-water mixture is determined by correcting the influence of the slip.

In this paper the crystallizing metastable zone of oxalic acid in aqueous solution is investigated by usingthe laser scattering method,which detects appearance of nucleus on line,at 20 ℃,30 ℃,40 ℃,50 ℃,60 ℃ respectively. At the same time, the effect of the rate of stirring,the rate of cooling and impurities on the width of the crystallizing metastable zone is studied. The data of crystallizing metastable zone is obtained. The equations of the width of the first and second crystallizing metastable zone with cooling rate are b_Ⅰ=22.63×(Δθ_maxⅠ)~1.1; b_Ⅱ=2.66×(Δθ_maxⅡ)~1.55. The study provided the theoretical foundation for crystallizerdesign and operation.

The laminar boundary layer theory is used to analyze the film condensation on a vertical plate. The calculated result is well consistent with the experiment and empirical relation of the laminar film condensation. A convection number E is presented,which shows the contribution of convection to heat-transfer in film condensation. When E is less than 1,the condensation region is controlled by conduction. When E is far less than 1,the region is called Nusselt region. When E is larger than 1,the region of condensation is controlled by convection. When E is much more than 1,Co_m is proportional to Re_L~1/3.

Based on the Corresponding State Theory (CST) and other methods for predicting transport properties,a new corresponding state method is developed to estimate the viscosity from thermal conductivity and to estimate thermal conductivity from the viscosity of freon at the saturated liquid state. The HFC134a is taken as the reference fluid in the method. The average deviation of thermal conductivity estimated from viscosity is less than 7%,while that of viscosity estimated from thermal conductivity is less than 8%,which can meet the demands of engineering applications.

The local bubble diameter profiles of the gas-liquid two-phase self-aspirated reversed flow jet loop reactor were studied experimentally by using internal camera CCD bubble measuring technology. The experimental results show that the local Sauter bubble diameter profile decreases with increasing liquid jet flowrates and nozzle diameter in both the jet region and the tubular flow region inside the draft tube. Bubble diameter profiles follow inverse Gaussian Distribution in the jet effective region while inverse parabolic distribution in the tubular flow region inside the draft tube.