In this present work, a numerical study of conjugated heat and mass transfer along a vertical tube was performed. The effect of the salinity in the water film is investigated. The film is falling along a vertical tube heated by a uniform heat flux. The numerical method applied solves the coupled governing equations together with the boundary and interfacial conditions. Results are presented for pure, brackish and seawater. Parametric computations are performed to evaluate evaporation and salinity progression along the tube. A comparison of operating conditions effects (pressure, film flow rate, tube length and wall heat flux) is made to enhance the effectiveness of desalination. (C) 2017 Elsevier B.V. All rights reserved.