The falling film evaporation outside the elliptical tube was studied and compared with the circular tube for the design and improvement of seawater desalination system using the method of theoretical analysis, CFD numerical simulation and experiments. The experiment shows that the thickness of liquid film outside elliptical tube of E (ellipticity) = 1.5 obtained from the simulation agrees well with the experimental data and the maximum deviation is within 8%. This fully illustrates that the numerical model is correct and that analog calculation is feasible. The experimental results also manifested that heat transfer coefficient of the system with E = 1.5 elliptical tubes increases by 20-22% compared with circular tubes. This study testified that it is superiority and feasibility that elliptical tubes were applied to falling-film evaporation and seawater desalination of horizontal tubes. The exploratory researches will be conducted for promoting the design and application of falling film evaporation with elliptical tubes in the seawater desalination system. (C) 2015 Elsevier Ltd. All rights reserved.