To predict the concentration dependency of diffusion coefficients in binary liquid mixtures, a conflgurational relaxation model proposed by Gray was developed with reference to the recent investigation for the micro-kinetics of molecular motion. The physical supposition of this model is that the evolution in the pair configuration space obeys a relaxation equation and that the conflgurational relaxation takes place when the free vacancy is located at the neighborhood of the first shell molecule. An important relation between shear viscosity and self-diffusion coefficients was derived by eliminating the relaxation rate coefficient from the equations for them. From this model, the concentration dependencies of self- and mutual diffusion coefficients for nonassociating binary liquid mixtures are predictable.

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Some features of froth density distribution on a perforated plate and their effects on froth height are discussed both experimentally and theoretically.
The following results are obtained:
1) Horizontal profiles of froth density in the region between the crest of outlet weir and the froth surface are uniform, while those near the plate surface are non-uniform. The vertical profiles of froth density in the region where the horizontal profiles are uniform are explained by a theoretical equation derived on the assumption that the sum of potential and kinetic energies of froth volume is minimum under steady-state conditions.
2) By this equation mentioned above, the height of the region between the froth surface and the crest of outlet weir is found to be proportional to the square root of the liquid flow rate. This relation is almost independent of the gas flow rate.

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This paper presents the results of an investigation of heat transfer to a flow of air in an annulus under an electric field applied between the wall of a tube and a concentric wire electrode. By electrically induced disturbance, the heat transfer rate in the low Reynolds number region is increased, being accompanied by the augmentation of axial pressure drop. At high Reynolds number, however, this augmentation is not noticiable. Augmented heat transfer and pressure drop coefficients were correlated in non-dimensional terms derived from the similarity principle and analytical cinsideration of the predominant electric effect. Moreover, semiempirical formulations of these augmenting mechanisms were attempted by analyzing the measured temperature profiles and flow behaviour.

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Changes of the volume and the surface area of cavity formed by bursting air bubble at the surface of distilled water were observed for bubbles of diameters rang from 0.19 to 1.23cm. The variations of shape of interface with time were clarified from high-speed photographs. The velocity of incoming water to the cavity was measured.

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To achieve an effective distillation in a wetted-wall column in the range of low liquid reflux flow rate, a swathed glass tube, a ground glass tube and a stainless steel mesh tube were used as the wall surface with improved wetting characteristics. Their efficiency results have shown a serious dependency of wettability and an effect of heat transfer from surroundings to system and between phases. The swathed glass tube has the widest range for effective operation of the three in a surface tension positive system, and also shows an extremely good performance in a negative system in comparison with smooth glass tube. And the other two, which have the same efficiency as that for the swathed tube in a positive system above the minimum wetting rate, are more wettable and effective than the smooth glass in a negative system.
Analytical treatments have been also made by use of a model to consider the effect of vaporization due to heat transfer. The result obtained points out a significant effect of evaporation in the low vapor flow range and accounts for the deviation of the experimental data from theoretical solution in such a range to some extent.

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The performance of the differential contacting distillation column with external heating or cooling was analyzed for four simple cases with the assumption that either mass transfer coefficient or H.T.U. is constant. The numerical evaluation as the ratio of N.T.U.s of the columns with and without heat exchange shows obviously that such heating or cooling in the differential contacting column has a quite different effect upon column performance from that in the plate column. It has been also pointed out that whether improvement or deterioration of column performance results from heating or cooling is likely to depend on the value of reflux ratio.
For total reflux operation, the analysis gives simple equations to predict N.T.U. under heating or cooling conditions.

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Numerical analyses of the desublimation rate in an annular-tube cold trap were carried out. Dimensionless parameters necessary to obtain the thickness of the growing solid phase were derived, and the effect of each parameter on the desired cooling length of cold trap was investigated by using the reference distance.
Experimental studies of the desublimation process also were made using water, benzene or carbon tetrachloride vapor as a condensable gas. Various desublimated states on the cold surface were observed through a transparent outer tube, and the thickness of the growing solid phase was measured along the axial direction. Some representative results for the thickness were compared with those obtained by numerical analyses, and were in good agreement with them.
Furthermore, some phenomenalistic studies were made with respect to the dependency on the contents of inert gas to the apparent density of solid phase, the influence of free convection and the occurrence of cracks.

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Liquid-phase mass transfer mechanism in ion exchange accompanied by chemical reaction was analyzed under the condition that neutral salt and acid or base coexist in the solution. The derived theoretical equations of liquid-phase effective diffusivity and the ratio of exchange rate with chemical reaction to that without reaction agreed fairly well with the experimental results.

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Permeation of benzene, cyclohexane, n-hexane and toluene through polyethylene films of different densities was studied by a gravimetric method and the values of permeation constant are presented. The values are converted to diffusivity with the aid of sorption equilibria.
Activation energy of diffusion is correlated to the cross-sectional area of permeant molecules.
Furthermore, the change of energy with the amount sorbed is discussed.

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The behavior of aerosols undergoing Brownian coagulation, Brownian diffusion and gravitational settling in a closed chamber was studied by solving the basic equation, the so-called population balance equation, numerically for a polydisperse aerosol system and analytically for a monodisperse system, and then the results were examined by experiment. In solving the basic equation, two dimensionless parameters, which are determined by the initial properties of an aerosol and the chamber dimension and also characterize the relative effects of Brownian coagulation and Brownian diffusion to gravitational settling, were introduced in order to generalize the behavior under arbitrary conditions. The calculated results, the time-dependent changes in particle number concentration and particle size distribution for a polydisperse system, were presented graphically by using the above two parameters. And further using these parameters, the domains of the three controlling factors were mapped to show the extent of each effect of these factors under various conditions for a monodisperse system. Some of the calculated results were compared with the experimental results obtained by the ultramicroscopic size analysis previously developed by the authors.

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The velocity of thermophoresis of aerosol particles in the slip flow region, about which no conclusion has yet been drawn from the many results of experimental and theoretical work, was studied from the experimental point of view. A new experimental method using an ultramicroscope was developed to meet most of the necessary conditions to obtain reliable data on thermophoresis, such as accurate observation of velocity under an accurately known temperature gradient and prevention of the action of any forces except thermal force. The experimental results were compared with some of the most representative theories, and were found in good agreement with Derjaguin''s theory.

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