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Since the first work of Tepe and Mueller and until now, there have been published hundreds of studies with the results of heat transfer investigations in vertical and horizontal tubes with vapour condensing of various liquids. Dozens of methods and formulae based both on the results of the theoretical research and on the experimental data have been proposed. The existence of more than 50% discrepancy in different experimental data and various empirical and theoretical relationships is shown. Thus, the absence of both substantiation of different methods and explanations of methods disagreement both between themselves and with different experiments is noted. Also, there are often no remarks concerning boundaries for the use of proposed relationships. There is proposed a simple semi-empirical correlation for heat transfer prediction in condensing inside the plain tubes at the annular and intermediate flow of the phases. This correlation is based on the nature of film condensation process and on the specific features of the results of theoretical solutions. The range of application of complexes, which determine the heat transfer process, is also substantiated. Good convergence of the new method with the experimental data on condensation of steam, carbon dioxide, hydrocarbon refrigerants and other various fluids inside horizontal and vertical tubes is shown.

479The problem about cooling a steam-gas mixture in a flowing bubbling layer (a dynamic two phase layer with the light and heavy phases moving with nonzero velocities) is of interest for high efficient open type heat exchangers for utilizing the heat of flue gases from various power installations [1]. The extent to which the processes running in the considered system have been studied is as follows. Dependences for determin ing the coefficients of heat and mass transfer from gas eous inclusions to liquid are not available in the litera ture. However, the authors of some works (see [2,3]), as well as data presented in [4,5] indicate that sur rounding liquid is heated quite intensely in immediate vicinity of the phase mixer. Hydrodynamic studies, in particular, those concerned with a bubbling mode in small diameter vertical tubes [6,7] were limited to studying the structure and parameters of flow in seg ments with considerable heights. The region in the neighborhood of a phase mixer, in which considerable parts of mass and heat are transferred, remained obscure. Some gaps in hydrodynamic studies con cerned with setting up a flowing bubbling layer (the influence the device's geometrical parameters and velocity at which gas is supplied through the phase mixer have on the layer structure and the characteristic flow modes of the flowing layer) are filled in [8].The studies were carried out on an experimental installation containing the following main compo nents: a chamber for mixing air and steam, a water supply chamber, an orifice, a working channel, a liquid collection chamber fitted with a separator, a steam generator, an air heater, and an instrumentation sys tem (Fig. 1). Vertical tubes with diameters of 41.0, 31.5 and 23 mm and heights of 204 and 103 mm served as a working channel.Each experiment was carried out in two stages. In the first stage, which was carried out after certain oper ating parameters were reached in the installation, the channel's working height (at which the heat and mass transfer processes take place) was experimentally determined by directly measuring (by means of special thermocouples installed in capillary tubes) the tem perature of two phase medium both along the height (at distances equal to 7.6, 18.6, 29.6, 40.6, 60.6, and 100 mm from the orifice) and over the tube cross sec tion (at the center, near the wall, and between the cen ter and wall). In the second stage, the values of quan tities characterizing the intensity of heat and mass transfer processes (flowrates of water, air, and steam, and the temperatures of water and of the "wet" and "dry" thermometers for steam-air mixture at the inlet to the channel's working section and at the outlet from it) were measured at the same values of operating parameters. In so doing, the holes along the tube height through which the above mentioned thermo couples were inserted were blanked by special plugs.During the experiments, the operating parameters were varied in the following ranges: the volume density of spraying Q spr = (1.097-33.50) × 1...