In the Horizontal inner Tube Evaporators (HiTE), evaporation takes place inside the tubes. The sea water is fed into the tubes, which is then heated from outside of the tubes either by steam or hot water. The seawater is heated until it reaches boiling temperature inside the tube. Due to both raising temperature as well as decreasing pressure during upstream flow more and more vapour is released. The resulting turbulent fluid/vapour mixture has a very good heat transfer, increasing the efficiency of the unit. The vapour is condensed to the desired distillate of high quality.
The design uses multiple stages at which seawater is evaporated. The follow-up stage uses the heat from the previous stage to heat up the seawater. This way the energy is recovered, increasing the total capacity of fresh water produced.