MATHEMATICAL DESCRIPTION OF THE PROCESS OF FILM CONDENSATION OF VAPORS FROM STEAM-GAS MIXTURES

Abstract

This article presents an analysis of the mathematical description of the process of film condensation of vapors from vapor-gas mixtures. Taking into account the considerable variety of effects that occur during the flow of films in processes in which phase transformations occur, the complexity of the mathematical description of the flow of condensate films becomes obvious. This complexity of describing the process is aggravated by the combination of heat and mass transfer, non- isothermic, and changes in such properties as surface tension, viscosity, and density. To describe the flow rate and film thickness during film condensation, a fundamental system of equations is used, and the equations of dynamics and continuity in the long-wave approximation are also taken into account. The estimation of the propagation length of nonlinear waves in condensate films with varying flow rates showed that with an increase in the condensation intensity, the role of the proposed corrections increases, but within the limits of the validity of the thin-film approximation does not become decisive and significant. During the description of the process of film condensation of vapors from steam-gas mixtures, it was found that when the basic conditions are met, the influence of undulation manifests itself mainly through an increase in the heat exchange surface, and the contribution of surface forces to the intensification of the process, i.e., an increase in condensate consumption, is no more than 10-12%