A molecular thermodynamic model for the calculation of ionic mean activity coefficients in electrolyte aqueous solution is developed by treating the ion - ion electrostatic interactions with mean spherical approximation (MSA) of all particles in the solution and other interactions with perturbation theory, respectively. Only the soft diameters of cations are correlated as the adjustable parameters in this model. The mean ionic activity coefficient data of 52 electrolyte (1-1,1-2,2-1 and 2-2 types) aqueous systems are correlated. Compared with other models, this model is rather simple and applicable and the calculation accuracy is satisfactory as well.

Combining the Voigt creep model of viscoelastic solid and Flory - Huggins mixing model which are used to calculate the Gibbs free energy contributed by creep of polymer and mixing of polymer and penetrants, respectively, a transport model of penetrants in polymer membrane was established. The effect of model parameters on the sorption and desorption curves was simulated. The model can satisfactorily correlate the experimental sigmoid sorption curves and predict the corresponding desorption curves. It is shown that this model is more flexible and fewer model parameters are required as compared with Cranks model.

A novel concept of gas - liquid reactors, bubble effectiveness, is presented. Through theoretical analysis and derivation, the expression of single bubble and bubble swarm effectiveness is obtained. It is found that the bubble effectiveness depends on a dimensionless group ψb, which includes the effects of properties of reaction system, operating condition and configuration of equipment.

An improved advancing front model for type II facilitated transport has been developed. The proposed model not only takes into account the mass transfer both inside and outside the emulsion globules , the interfacial chemical reaction, but also the influence of the permeation swelling and the breakage. Computer simulation was performed by the Crank - Nicolson implicit method. The results indicate that the process of computation is converged steadily and the model prediction agrees well with the experimental data.

The process of oxidative dehydrogenation of butene to butadiene catalyzed by B - 02 is studied in a Gas - Solid - Solid Circulating Fluidization Reactor (GSSCFR) . The experimental results showed that the conversion of butene can be increased by 10% ~ 20% , the yield of butadiene can be increased by 10% ~ 15% in GSSCFR against those in industrial adiabatic packed- bed reactor, and the steam -to - butene mole flux ratio can be reduced from 16 to 8. On the basis of the hot model experiments and one - dimensional pesudo - homogeneous model, the hot model powder - to - gas mass flow ratios are studied with mass and energy balance. Furthermore, the characteristcs of removing reaction heat by the heat carriers are analyzed.

The relationship between input and output of a dynamic system is analysed and a new - type structure of neural networks is proposed in this paper. There is a specific layer added in the network which is the first hidden layer. Each node in the first hidden layer only receives the input having the same property and produces an integrated signal. The network, as compared with the conventional network, is greatly reduces the number of weights. So it is of great benefit to speed up the training network and to improve the stability and convergence of the network. Then the inverse dynamic neural network controller has been discussed. It is suggested to add a control deviation in the input layer to improve the model accuracy of the controller. Finally, the effects of the structures above mentioned are demonstrated by using CSTR dynamic simulation and control.

The rate-controlling step of resoluting N-acetyl-D, L-alanine with porous immobilized Aspergillus Oryzae cells was studied. In the batch reaction with high ratio of substrate to catalysts, the rate ?controlling step was determined by measuring the concentration variation of produced L-alanine in solution. The results showed that the substrate concentration and temperature were important factors which influenced the rate - controlling step. The results of model calculated with effective diffusion coefficient obtained were in agreement with experiment data.

The bifurcation diagrams of state variables versus operation parameters for a continuous isothermal mixed - suspension, mixed - product removal (MSMPR) crystallizer have been obtained by resolving the steady state equations with the continuation technique of nonlinear equations. The number of steady states of the continuous MSMPR crystallization process for various multiplicity regions is determined and the criteria of multiplicity(i. e. , multiple steady states) and uniqueness, which is only dependent of the kinetic properties and operation parameters of the crystallization process, is developed by the use of bifurcation theory. In addition, the stability of steady states is analyzed by using the Routh - Hurwith criteria.

The ozone concentration in liquid phase vs. time during ozone absorption in water and the influence of pH value are studied. On the basis of the film theory a mathematical model is established to predict the ozone concentration in aqueous solution. The theoretical results are in agreement with the absorption data. Meanwhile, the transport phenomenon in ozone absorption is also studied. Analytical solutions are derived to predict enhancement factors in ozone absorption processes accompanied with ozone decomposition and a series of first or second order ozonation reactions. Compared with literature data the predicted results are reasonable.

The separation technique of solvent extraction based on reversible chemical complexation can have high capacity and high selectivity for separating polar organic solutes from dilute solution. By using TOA and TBP as complexing agents, n - octanol, MIBK or kerosene as diluent, a series of extraction equilibrium experiments for phenolic aqueous solutions were carried out. In a wide - range of pH the effects of solutes, type and concentration of complexing agents, pH value of aqueous solutions and diluents on distribution ratio D are discussed. An expression of equilibrium distribution that includes chemical complexation and physical extraction simultaneously has been proposed.

The extraction equilibrium characteristics of amine solution systems have been studied. D2EHPA(in kerosene) is selected as a solvent to separate amines from dilute solution. The effects of pKa of amines, complexing agent concentration, and pH of solutions are discussed. An expression of equilibrium distribution that includes chemical complexation and physical dissolution simultaneously has been proposed. With the FT-IR spectroscopy, mechanism on of amines with D2EHPA is investigated.

Based on the lump parameter models developed in this paper, general transfer functions for transient responses of fluid outlet temperatures of two - stream plate - fin heat exchanger to changes of either cold fluid inlet temperature or cold fluid flow are derived. The models have been verified by experiments. Detailed analyses show that applicable linearized ranges for transfer functions are unlimited for fluid temperature changes, or △m/m < 30% for fluid flow changes. When both fluid temperature and mass flow change simultaneously, the applicable linearized ranges are limited to their 20 percent changes of these two parameters.

Based on the relation between the trailing bubble velocity and the length of liquid slug ahead of that bubble obtained in the experiment, this paper presents a model that is able to calcukte the slug length distribution at any designated location along the tube. The results of the calculation is in agreement with the experimental data.

The residence time distribution in a packed column containing Mellapak 250Y and Mellapak 350Y was measured by pulse tracer technique, and the liquid effective velocity was evaluated by optimization method. It was found that the liquid effective velocity is proportional to the cubic root of liquid flow rate. Two dimensionless numbers, Nv and Nw, were proposed to represent respectively the liquid effective velocity and the liquid flow rate. The experimental data were correlated satisfactorily by a dimensionless equation involving No and Nw. Comparison was made between the experimental data and the calculated results by the proposed equation, Bravos method and the method from falling film theory.

With air and water as the working fluids, an experimental study on the characteristics of the interfacial waves in gas - liquid two - phase flow in a horizontal rectangular channel was conducted by using three two - parallel conductance probes to measure the instantaneous liquid film thickness. The test section was entirely made of plexiglass plate and the length is 6690mm long. Its cross section was 150mm×25mm. In this experiment the maximum gas superficial velocity was 14.6m·s-1 and the water superficial velocity 0.110m·s-1. The wave pattern and flow pattern of gas - liquid two- phase flow were distinguished and defined, and compared with the results of previous studies. Furthermore, the characteristics of interfacial waves, such as wave speed, wavelength, wave frequency and wave amplitude were investigated in terms of the gas and liquid volumetric fluxes.

An improved algorithm for calculating the complex of time series of differential pressure fluctuation in pressurized fluidized bed is proposed by using the method of roughing chaos based on golden section. The calculated complex is similar to the fractal dimension on different branches in experiments. It is simpler and more useful than the algorithm of the fractal dimension.

Based on the population balance theory, a partial mixing series model, which integrates the kinetics of crystal growth with the hydrodynamics of characterization of the geometric properties and operating parameters of the device, was developed to describe the behaviour of three - phase fluidized bed crystallizer. With this model, the concentration distribution of the solution, size distribution of the crystals and the mean size of the products were estimated. The calculated results agreed well with the experimental data for sucrose crystallization in a three - phase fluidized bed. The fact indicates that the model is quite reasonable, practical and capable of providing a basis for the design and scale up of three - phase crystallization systems.

This paper presents the characteristics of three - phase mixing in terms of the critical impeller speed of complete suspension of solid, gas and solid dispersion state, stirred power, gas - liquid mass transfer coefficient for different suspension concentration and gas volume in liquid by using a new type axial impeller(K4) in mechanically stirred vessels. It is revealed that the critical impeller speed Njsg and stirred power per unit volume Pjsg/ V for incipient complete suspension state increase with increasing gas volume. The aeration coefficent k and aeration factor K represent the intensities of these effects, and usually k= 0.124 ~ 0.580, K = 0.72. The total dispersion process in three - phase system can be defined as two dispersion regions. In the first dispersion region, the gas dispersion ia from flooding to complete dispersion while the solid dispersion is from the state of lift - off to complete suspension, In the second dispersion region the gas and solid concentrations are well distributed in the stirred vessels, which is regarded as pseudo - homogeneous dispersion. The impeller speed index m in the equation of power consumption is close to the index for homogeneous system, usually, the mean speed index m = 2.67. The volumetric mass transfer coefficient KLa increases with incresing gas volume as a result of gas holdup increaing with the increasing of the gas volume. The power index β accounts for the effect of the stirred power on the volumetric mass transfer coefficient KLa and usually β= 0.71 ~0.93.