Analytical model for the condensation heat and mass transfer characteristics of binary zeotropic mixtures

An analytical model was developed to study the condensation heat and mass transfer characteristics of binary zeotropic mixtures for annular flow inside a horizontal tube. The model was based on non-equilibrium film theory including consideration of the surface tension variation in the liquid phase as the concentration changes. The model was validated by comparing the calculated heat transfer coefficient with experimental data from the literature for methane/ethane mixtures with various compositions and mass fluxes. The model was then used to study the effects of composition, mass flux, inlet pressure and tube diameter on the heat and mass transfer resistances in the vapor phase and the heat transfer coefficient during condensation of methane/ethane mixtures. The results showed that the mass transfer resistance in the vapor phase was important in the high vapor quality region with the heat transfer resistance in the liquid phase being more significant in some cases. (C) 2019 Elsevier Ltd. All rights reserved.