V. N. Babak

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.

Hydrogen transport through a membrane module based on a palladium foil

Experimental data are presented and a mathematical model is suggested for hydrogen transport through a palladium membrane module. The basic working element of the module is a piece of palladium foil secured between two pieces of fine-mesh metallic gauze to prevent the rupture of the foil because of the difference between the outer pressures applied. It is demonstrated that, under the experimental conditions considered, the effect of the supporting metallic gauzes can be neglected. An expression is reported for the hydrogen flux through the foil as a function of the foil thickness and applied pressures. In the particular case of fairly high pressures, the hydrogen flux obeys the well-known Sieverts law, being limited by proton diffusion in the palladium lattice. At low pressures, the hydrogen flux is limited by adsorption-desorption processes on the foil surface. The preexponential factor in the Sieverts law for pure palladium membranes has been refined on the basis of experimental data for the membrane module.

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.

Heat and momentum transfer in liquid films with temperature-dependent viscosity

The distributions of film velocity, temperature, and thickness at the inlet of a film heat exchanger at large thermal Peclet numbers are shown to depend on a dimensionless parameter. Analytical solutions are obtained for small and large values of the parameter.

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.

A procedure for calculating matrix heat exchangers formed from perforated plates

A procedure is proposed for calculating matrix heat exchanger-recuperators, and it is shown that in the general case it is possible to adequately tabulate the efficiency as a function of the length of the apparatus for limited ranges of the important parameters.

Two-phase mass exchange in irrigated tubular packings for the cocurrent laminar phase flow

The hydrodynamics and two-phase mass exchange in packed film devices were studied for the cocurrent laminar flow of a gas and a liquid. The mass-transfer problem was solved by the approximate Galerkin method. Two known absorption factors were selected as crucial parameters. The analytical solution was found within a limited absorption plane. Outside this region, the solutions were simplified, and the dimensionless flows became one-parameter length functions. In particular, the conditions under which the resistance to mass transfer was concentrated in a given phase and corresponding flows became independent of the absorption factors were found.

Optimal conditions for vacuum desorption

The optimal conditions for the vacuum desorption of components from liquid solutions are found-the maximum pressure and minimum acceptable density of irrigation. The evaporative equipment is modern regular film tubular nozzles. The laminar pressure of liquid and vapor in the downstream parallel flow mode is assumed. The vacuum desorption from water solutions of some inorganic gases that have both low and high solubility is considered as an application to the theory.

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

AbstractsMass 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.

Vacuum desorption of gases from inorganic solvents with various boiling points

The vacuum desorption of gases from inorganic solvents with low and high boiling points is reported. A thin-film evaporator consisting of regular tubular packing elements is considered. A laminar downward cocurrent flow of liquid and vapor is analyzed. General theoretical propositions are illustrated by the example of the desorption of simple gases from lower alcohols (methanol, ethanol) and liquid naphthalene, as well as by the example of removing the products of ester decomposition from esters at high temperatures.