V. E. Nakoryakov

Heat and Mass Transfer During Vapor Absorption by a Stagnant Solution Layer

Based on simple models of nonisothermal absorption for the cases of long and short times, the effect of the heat‐generation and heat‐extraction rates on vapor absorption by a stagnant solution layer is analyzed. Models taking into account and ignoring the motion of the interface between the phases are considered. Results of an experimental study of steam absorption by a stagnant water/LiBr solution are described. Time dependences of temperatures at various heights inside the liquid layer and of the absorbed mass, and also temperature and concentration profiles at various times, are reported. A comparison of predicted values with experimental data is given.

Effect of Surfactant Added in Small Amounts on Nonisothermal Absorption: an Experimental Study

Results of an experimental study of water‐vapor absorption by a stagnant layer of the aqueous solution of LiBr with admixed octanol, used as a surfactant, are described. Time dependences of temperature at various heights of the layer, time dependences of absorbed mass, and temperature and concentration profiles at various times are reported. A comparison with experimental data for surfactant‐free solutions reveals an enhanced action of octanol on water‐vapor absorption and an increase in the absorbent surface temperature at the initial stage of the process.

Pressure Waves in a Gas–Liquid Medium with a Stratified Liquid–Bubbly Mixture Structure

Evolution and decay of pressure waves of moderate amplitude in a vertical shock tube filled by a gas–liquid medium with a nonuniform (stepwise) distribution of bubbles over the tube cross section are studied experimentally. The gas–liquid layer has the form of a ring located near the tube wall or the form of a gas–liquid column located in the center of the tube. It is shown that the nonuniformity of bubble distribution over the tube cross section increases the attenuation rate of pressure waves.

Evolution of pressure waves in a liquid with bubbles of two dissimilar gases

The structure and dissipation of moderate‐amplitude pressure waves in a liquid with bubbles of two dissimilar gases (freon and helium) are experimentally studied. It is shown that introduction of a small (by volume) quantity of helium bubbles with a high thermal conductivity into a liquid with poorly heat‐conducting freon bubbles, sharply increases the rate of damping of solitary pressure waves.

Study of heat transfer of a helium–xenon mixture in heated channels with different cross-sectional shapes

This paper describes the results of an experimental study of heat transfer in the case of the flow of a helium–xenon mixture with a Prandtl number approximately equal to 0.23 and the flows of pure helium and air in heated tubes of circular or triangular cross sections with a constant density of the heat flow. The region of thermal stability is studied. The law of heat transfer on the stabilized region is compared with known relationships. The approach that helps obtaining an expression for the calculation of heat transfer in heat transfer devices with circular and triangular cross sections, which operate in a mixture heating mode on the initial region, is developed.