Analysis of long-time interaction of perturbations in problems of macrokinetics

We developed an approach for the reduction of systems of nonlinear partial differential equations to the general nonlinear parabolic equation for a complex amplitude of an envelope wave. The equation is complexly derived: by using wave packages, method of many scales, modification of Mandelshtam method and taking into account group velocity of an envelope wave, that is typical for an actual nonlinear dispersive medium. We consider the features of such modeling for a system with nonlinearities occurring in the simplest model of a nonisothermal chemical reaction, in particular, of thermal autoignition and flame propagation.     

Removal of impurities from liquid solutions by vacuum desorption with solvent evaporation

Mass transfer with solvent evaporation in the vapor-liquid two-phase film evaporators used for the removal of undesirable impurities from liquid solutions at low pressure is studied. The average concentrations of solution components in the falling liquid film are determined. The most efficient operating conditions for impurity removal, in which the resistance to mass transfer is concentrated in the liquid phase, are found. Original Russian Text ? V.N. Babak, T.B. Babak, L.P. Kholpanov, 2008, published in Teoreticheskie Osnovy Khimicheskoi Tekhnologii, 2008, Vol. 42, No. 6, pp. 654–670.     

Unsteady-State Mass Transfer of Gases between Two Quiescent Phases

It is shown that many gases interact with water by reactions similar to that characteristic of sulfur dioxide. The unsteady-state transfer of such gases from one quiescent phase into another is studied in the cases where these gases are absorbed by a liquid or released from a liquid solution.     

Mathematical simulation of the dynamics of a dispersed phase in free gravitational convection of a viscous incompressible liquid in a square cavity

The problem of motion of monodisperse spherical particles in a heterogeneous medium in nonisothermal free convection of a carrying incompressible liquid in a square cavity with inhomogeneous distribution of temperature on the walls is considered. The problem is solved by the finite-difference method via joint solution of equations for the carrying phase in Euler variables and the equation for a disperse particle in Lagrange variables. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 81–89, January–February, 2008.     

A note on two-phase film mass transfer without mass forces

Some aspects of two-phase film mass transfer in the absence of mass forces are examined. The results are novel in that the parametric equations contain expressions which take into account the physical properties of the contact phases.     

Turbulent conjugate heat-and mass transfer in chemical conversions in a tubular reactor

A model of turbulent heat-and mass transfer with nonlinear sources (sinks) that appear as a result of chemical reactions of the first and second orders has been developed. The conjugation condition (equality of temperatures and local fluxes) at the reactor — coolant interface was used for this purpose. A finite-difference numerical solution by the alternating direction method is obtained. The influence of the coefficients of turbulent viscosity on heat-and mass transfer is investigated. The model has been tested on the example of modeling fast polymerization processes. It has been established in practical calculations of the processes of fast polymerization that instead of the model with variable coefficients of transfer and velocities of liquid motion one can use its approximation with constant coefficients of transfer and velocities of liquid motion. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 6, pp. 73–85, November–December, 2007.     

Interface Oscillations in Boiling

Interface oscillations during boiling are studied experimentally and theoretically. The output-signal spectra of light and acoustic sensors indicate that the liquid-pressure and interface oscillations are interrelated. A model is suggested for the oscillations of a bubble growing on a heating surface, and the existence of an attractor is deduced for the first time from the solution of model equations. The data obtained enable one to determine the ranges of interface oscillation amplitude and frequency and can be used in the modeling of boiling.     

Modeling of thermal processes in laser sintering of reactive powder compositions

A two-dimensional mathematical model describing a combination of the processes of self-propagating high-temperature synthesis and selective laser sintering of powder compositions (it is controlled by the laser-radiation energy) has been proposed. The model makes it possible to evaluate the correspondence of the geometric characteristics of the system to the values of the velocities of a moving laser spot at which the layer poured completely reacts in the vicinity of the spot. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 6, pp. 42–48, November–December, 2005.     

Fractional integro-differential analysis of heat and mass transfer

Application of the methods of fractional integro-differential analysis to an inhomogeneous canonical heat-conduction (diffusion) equation with inhomogeneous boundary conditions has enabled us for the first time to reduce the canonical heat-conduction equation to three equations of lower order that contain fractional-derivative operators. Examples and an analysis of those fundamental new possibilities that are opened up by such an approach to a wide class of problems of heat and mass exchange, combustion, self-propagating high-temperature synthesis, etc., have been given.__________Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 78, No. 1, pp. 35–47, January–February, 2005.