CONDENSATION OF A VAPOR WITH INCONDENSABLES - AN IMPROVED GAS-PHASE FILM MODEL ACCOUNTING FOR THE EFFECT OF MASS-TRANSFER ON FILM THICKNESS

An improved gas phase film model is presented for calculation of local skin friction, heat and mass transfer coefficients in condenser design. The model accounts for the effect of the local mass transfer intensity on film thickness in turbulent flow. Predictions from the proposed model and from the classical 'film theory' and 'condensation curve' methods are compared with experimental data for a saturated steam-air mixture inside a 2 cm diameter tube under the following conditions: pressure, 1-1.5 bar; air mass fraction, 2-30%; inlet velocity, 5-50 m s-1. Results indicate that for low values of the heat flux density (and for low values of the condensation rate) the three methods above are in excellent agreement with data. For high values of the heat flux density, the proposed model gives excellent agreement with the data but the classical methods do not. © 1990.