L. P. Kholpanov

Multicomponent isotope separating cascade with losses

Abstract The theory of multicomponent isotope separation cascade with losses is developed. The losses from each stage of a cascade are set proportional to the flow entering the stage, the fraction of flow lost per stage being constant. The interstage flows of each component are expressed as simultaneous linear equations and solved explicitly in the case where the separation factors do not vary from stage to stage. An illustrative example dealing with the separation of the 5-component tungsten isotope mixture in the matched abundance ratio cascade composed of gas centrifuges is included.

Mathematical Modeling of the Hydrodynamics over Permeable Surfaces

A mathematical model is developed to describe the flow of a two-phase heterogeneous medium over the surface of a porous body of arbitrary shape, through which there is filtration. The conservation equations of the mechanics of heterogeneous media are written in an orthogonal coordinate system and are solved by the method of surfaces of equal flow rate. The characteristics of the flows over the surface of a flat porous plate and over the inner surface of a rotating tapered porous rotor are numerically calculated.

Simultaneous Heat and Momentum Transfer in Two-Phase Film Systems at Low Pressure

The heat and momentum transfer in a liquid–vapor two-phase film system at high temperature and low pressure is studied as applied to removal of highly volatile fractions from high-boiling liquids. It is shown that the working zone can be divided into two regions, namely, the initial heating region and the evaporation region. The height of the former region is much smaller than that of the latter. The velocity and temperature distributions in the system are investigated.

Designing a Rectangular Sectioned Cascade by Approximating the Separation Factor

A powerful method is suggested for the calculation of the steady-state mass transfer for a multicomponent isotope mixture separated in a rectangular sectioned cascade. Based on the progressive approximation of the outlet concentration ratios, the method provides appreciable savings in computational time.

Theoretical study of hydrocarbon dehydrogenation at high temperatures

A theoretical study of hydrocarbon dehydrogenation in state-of-the-art packed tubular membrane reactors and in impermeable tubes is performed. Conditions of the efficient operation of apparatuses are found under which a high degree of hydrocarbon conversion and yields of products are attained. The possibility of experimentally determining a number of constants for the such processes is shown. Results of theoretical calculations are compared to experimental data for isobutane dehydrogenation.

Neumann-Lame-Clapeyron-Stefan Problem and Its Solution Using Fractional Differential-Integral Calculus

A method is proposed to solve boundary-value problems for parabolic equations with unknown boundaries (where the solutions join) moving according to time-dependent laws. This method is based on fractional differential-integral calculus. An integral relation between the temperature and velocity of the moving interface is put forward. Necessary examples are given.

Two-phase frontal polymerization of metal-containing monomers

A mathematical model of two-phase frontal polymerization in a moving conversion layer is proposed. Using fractional differential-integral calculus, an analytical solution for temperatures in the vicinity of the phase boundary (melting-polymerization) and the dependence of temperature at the front on the rate of the motion of the phase transition boundary are obtained. A formula for the front advancement rate that agrees with the experimental results is found, and a method for estimating the effective activation energy of frontal polymerization is proposed.

Identification of complex nonlinear processes

The estimation of the unknown parameters in models described by algebraic equations, ordinary differential equations, and partial differential equations, as well as the initial state vectors in these models, was carried out by the maximum plausibility technique. As in problems of parametrical identification, quality functions have a complex form and contain a significant number of local minimums; to decrease their amount and simplify the form of the quality function in regions far from the absolute minimum, the method of asymptotic decomposition was suggested for problems of the identification and estimation of the parameters. For the application of the suggested procedure, the technology of the parametrical identification of the physical-chemical processes in a furnace plant working in the mode of gas production with a fluid bed was introduced. A measurement model was developed by the experimental data obtained during the combustion of brown coals in primary furnaces with a fluid bed at HES-2 in Chelyabinsk.

Absorption of Carbon Dioxide by Alkali and Aminoalcohol Solutions in Two-Phase Systems

Carbon dioxide absorption by alkali and aminoalcohol solutions is considered. If the concentration of the CO2-binding chemical far exceeds the equilibrium absorbate concentration, as in the industrially most important cases, this complicated process is essentially an irreversible second-order reaction.

Mathematical Modeling of Flows of Heterogeneous Media over Rotating Permeable Surfaces

Three-dimensional flows of heterogeneous media over rotating permeable surfaces are considered. The effect of filtration and lag of the liquid on the hydrodynamics of the film is studied. For some surfaces, numerical calculations are performed.