Evaporation in the HiTE takes place inside horizontally placed tubes. Seawater is fed into the tubes and heated from the outside with hot water or steam. Heating continues until reaching boiling temperature. Due to both the rise in temperature as well as a decrease in pressure during upstream flow, vapour is continually released. This vapour is finally condensed to the desired high-quality distillate.
The design uses multiple stages in 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, further increasing the total capacity of freshwater production and the overall efficiency.