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%

The paper presents an analysis of the mathematical description of the process of film condensation of vapors from steam-gas mixtures, taking into account the dependence of the processes of heat transfer and the hydrodynamics of the condensate film. It is established that the presence of an insignificant fraction of non-condensing gases sharply reduces the surface temperature of the condensate film. The numerical experiment has confirmed that the loss of stability of the film and its deceleration are associated with the temperature gradient on its surface. It is established that the influence of non-isothermicity on the characteristics of transfer processes can significantly change their flow mode even with small fluctuations in functional parameters. The influence of temperature on the condensate density leads to a certain increase in the average and local Nusselt numbers. As a result of the conducted studies, it was found that the dependence of the condensate density on temperature contributes to an increase in the average and local Nusselt number. This is confirmed by its fundamentally small effect on heat exchange under condensation conditions for liquids in the following range  ~ 10 10   4 2  .