Thin-film plants with different heating surface orientations are widely used in seawater technology. Despite the presence of various thermal schemes and construction of evaporating devices for plants of this type, comparison of their energy efficiency is absent. We compared the effectiveness of MSF thermal schemes and thin-film plants. The intensities of heat transfer by thin-film plants with seawater moving along the heating surface in the form of vertically-filmed descending and ascending two-phase flow and horizontally-filmed flow were analysed using our research and that of others.