Which of the freshwater generators listed below requires a source of heat and evaporates sea water at a location other than a heat exchanger surface?

Correct Answer: Option D — Flash type

Flash evaporators operate by spraying heated seawater into a chamber maintained at a lower pressure, causing the water to 'flash' into steam. This evaporation occurs in the space within the chamber rather than directly on a heat exchanger surface, which helps minimize scale formation on the heating elements themselves.