Direct contact condensation and momentum transfer in turbulent separated flows

Abstract

Analysis of the turbulent velocity and shear stress distribution in a separated two-phase flow shows that both the wall and interface shear contribute to the dissipation of energy in the liquid film. A suitably averaged turbulent energy dissipation provides Kolmogorov velocity and length scales in the liquid film. These scales are used in a turbulent eddy based surface renewal theory for condensation and evaporation of saturated vapor onto or from its liquid. The theory accurately predicts experimental data for horizontal, concurrent condensation of steam on water. Theoretical results agree with the form of existing turbulent correlations for heat and mass transfer processes such as condensation onto a falling liquid film and mass, momentum and heat transfer at the interface in separated flows. Comparison of the theory to previous work is included and guidelines for empirical correlations of data are given.