Measurement of turbulent fluctuations of vclocity gradient on the wall is important for thorough understanding of turbulence structure, mass transfer and heat transfer in the vicinity of the wall. This paper describes the principle of electrochemical technique as well as the measurement of two-dirnensional fluctuations of velocity gradient with a pair of semicircular electrodes. In a fully developed turbulent pipe flow with pipe diameter of 0.194 m and with a solution of iodine and potassium iodide as flow medium, the measured axial and transversal turbulent intensities of velocity gradient at the wall arc 0.3-0.33 and 0.11 0.12 respectively.

A molecular thermodynamic model of gas solubility in nonpolar solvents has been established. The Helmholtz energy of liquid mixture is calculated through the following three steps. First, the pure components in standard state are mixed isothermally to form an ideal gas mixture. Then each molecule is inflated into a hard sphere with diameter σ. The corresponding Helmholtz energy change is calculated by using the Mansoori-Carnahan-Starling-Leland equation. Finally, the molecules are charged with LJ 12-6 potential to form the real liquid mixture, where the structure is described by an approximated radial distribution function gij(r)=H(r-r)+βδ(r-rj). Henry’s constants are then calculated from residual chemical potential.With the use of the same LJ parameters, this model can predict the computer simulation results of Henry’s constant quite well. In this respect, this model is superior to Pierotti’s theory. For practical systems, Henry’s constants of various gases in C_1—C_(20) alkanes and their isomers, naphthenes, aromatic hydrocarbons and liquified gases can be well correlated over a wide temperature range using only one adjustable parameter. The predictions for △H_(s1), △S(s1) and V_1 are also satisfactory.

The molecular thermodynamic model established by Hu, Xu and Prausnitz for gas solubility in nonpolar solvents is extended to polar and electrolyte solution systems. The influence of ion charge on the Helmholtz energy of fluid mixtures is taken into account by considering the interactions between the charge of ions located in the first coordination shell and the dipole or induced dipole of the central solute molecules. The contribution of the ions outside the first coordination shell can be neglected owing to the symmetrical distribution of the positive and negative ions with respect to the central solute molecule. The model in this paper includes a correlation equation for the effective hard sphere diameter of ions and the Pauling’s crystal diameter, σ=ησ~(crystal), where η=-6.645+747.2511/T+2.95392×10~(-2)T-5.05798×10-~5T~2+3.2431×10~(-8)T~3, for T>453.15 K, η=1.021. Henry’s constants of various gases in water, alcohols, ketones, halogenated aromatics and naphthalene substitutes are calculated. For all of the 81 systems with 13 solvents whose maximum dipole moment is 2.83 Debye, satisfactory results are obtained with the use of only one adjustable parameter over a wide temperature range of 193.15—573.15 K. The results of calculations for 78 systems of gas solubility in 1-1 type electrolytic solutions indicate that this model can predict the Henry’s constants of gases in electrolytic solutions over a wide temperature range and a wide concentration range for electrolytes with the use of molecular parameters of gases in water only.

An isobaric vapor-liquid equilibrium apparatus at elevated pressure has been developed for measurement. The isobaric vapor-liquid equilibrium data of three binary systems (isobutene-isoprene, isobutene-chloromethane and isoprene-chloromethane) and a ternary system (isobutene-isoprene-chloromethane) have been determined at 1.03 MPa and correlated satisfactorily with the Martin-Hou equation of state (81).

A mathematical model for evaluating the separation performances of hollow-fiber membrane N_2—H_2 separators has been established. The influences of operating parameters and membrane characteristics on the hydrogen concentration of the permeated gas and the percentage recovery of hydrogen have been studied with the help of a digital computer using this model. The correctness of the model is proved by comparing the calculation results with the data obtained from the field test of three φ100×3000mm industrial scale separators.

The mathematical model of non-catalytic liquid-solid diffusion reactions discussed in this paper can be applied to quite different cases. The models in the literature such as unreacted shrinking core model, two stage model and homogeneous model can be considered as special cases of the above model which has been derived for leaching vanadium from steel slag with sodium carbonate and]or sodium bicarbonate solution reacting with two components in the slag simultaneously. The vanadium leaching reaction is inhibited by the solid product formed during the reaction. The power law equation can be used to represent the kinetic experimental data of leaching reaction. The model equations have been solved by orthogonal collocation and semi-implicit Runge-Kutta method. The parameters of the model have been estimated by the complex method. The calculated results based on this model is in good agreement with experimental data.

The vertical density profiles of the gas-liquid mixture on the flow-guide sieve tray and conventional sieve tray have been studied by gamma-ray absorption technique. It has been found that the inflection points of entrainment rates can be regarded as the criterion of transition of flow regimes and that the operating range between two inflection points is the transition regime. The relationships have been established for the lqiuid hold-up (or clear liquid height), the average dispersion density and the transition of flow regime.

In designing fluidized-bed equipment, it is important to determine the TDH (Transport Disengaging Height) for the dilute-phase zone. Until the present time, the empirical curve developed by Zenz and Weil in 1958 has been widely used. In the present paper, on the basis of the equation for the motion of single particle, methods for calculating gas velocity, particle velocity, and particle stagnation time and rising height in gas-solid flow, have been developed through theoretical analysis, resulting in an eight-parameter expression, Eq. (14), for computing TDH. This equation, which contains more parameters than those in any previous work, gives closer fit to experimental results, and is thus recommended for design.

Various methods for achieving dropwise condensation (DWC) are reviewed from the point of view of surface science. The objective of the present work is stated. In the experimental study, the surfaces of stainless steel and copper tubes employed were treated with various surface techniques, steam condensation under atmospheric pressure was carried out and steady DWC observed on these surfaces, and the mechanism of DWC formation on the treated surfaces was analysed. Experimental results and photographs of DWC are presented.

Technology of ion-plating and ion-beam mixing was employed to prepare surface alloys on copper tubes. Elements chosen for the purpose are Cr, Fe, Al, N, Bi, Sb, Sn, Se and In. Excellant dropwise condensation of steam was then obtained on some external surfaces of these copper tubes and the mechanism for the dropwise condensation was analysed.The surface characteristics of the Cu-Cr and Cu-Fe alloy layers were analysed by using XPS, AES and AES-PRO of PHI-550 multiple function electron spectroscopy.

Heat transfer characteristics of the new surfaces were determined through temperature measurements, and the results were compared with dropwise condensation (DWC) studies from various sources.Duration tests for DWC were carried out on two different surfaces, giving a duration of perfect DWC over 15000 hours.

A study on the migration behavior of the reactive disperse dyes containing β-hydroxyethyl sulphonyl sulphuric ester group at different stages of dyeing and thermofixation on the polyester-cotton blend was made. The sublimation and vapor-phase transport of the dyes during thermofixation were examined. It was concluded that thermofixation conditions affect the dye distribution between cotton and polyester in the blend. The relationship between the distribution and the molecular structure of the dyes was examined. A dyeing mechanism of reactive disperse dyes for polyester-cotton blend was suggested.

A pseudo-one-dimensional model comprising different coaxial mixing is proposed for the study of the liquid phase mixing in packed column. The model parameters are estimated by the optimal method of nonlinear programming, and the equivalent mixing coefficient is regressed in the form of dimensionless equation.

A two-dimensional model involving both radial and axial mixing under the condition of steady tracer injection from a point source is presented. The model parameters are estimated by the optimal method of nonlinear programming, using the two-dimensional RTD experimental data obtaincd in a 1m diameter packed column. Dimensionless equations for the evaluation of axial and radial Peeler numbers are regressed.