AN INVESTIGATION OF CONDENSATION FROM STEAM-GAS MIXTURES FLOWING DOWNWARD INSIDE A VERTICAL TUBE

This research investigates experimentally local heat transfer from con densation in the presence of noncondensable gases inside a vertical tu be. Using a novel experimental apparatus for accurately measuring loca l heat fluxes, an extensive data base has been obtained for the conden sation of pure steam, steam-air mixtures and steam-helium mixtures. Th ree different correlations, implementing the degradation factor method , diffusion layer theory, and mass transfer conductance model, are pre sented. The correlation using the simple degradation factor method has been shown to give satisfactory engineering accuracy. However, this m ethod is based on very simplified arguments that do not fully represen t the complex physical phenomena involved. Based on diffusion layer th eory and a mass transfer conductance model, more physically based corr elations were developed for the heat transfer of vapor-gas side. The t otal heat transfer coefficient predicted by the correlations from thes e two mechanistic models are in close agreement with experimental valu es. (C) 1997 Elsevier Science S.A.