This paper presents a conjugate approximate method for solving transfer problems in a two-phase (condensate-vapor) system that accounts for the peculiarities of atom-interface interactions and obtains a distribution function for the evaporated and reflected atoms. In this method, the Boltzmann kinetic equation is numerically solved for the vapor phase. The condensate matter and liquid-vapor transition layer are investigated through molecular kinetics and dense medium statistical mechanics. Finally, the proposed approach is validated by solving equilibrium saturation vapor-liquid lines of different substances as well as a nonsteady evaporation-condensation problem and by comparing the results with experimental data. (C) 2017 Elsevier Ltd. All rights reserved.