At present, MSF plants arc the most reliable source for the production of fresh water from the sea and all major plants are Luilt according to this principle . Compared to reverse osmosis, the specific prime energy consumption of MST processes is high evenn if the plants are designed as dual purpose plants .
Substantially lower prime energy consunptions in distillation can be achieved by the ME-principle . Despite its thermodynamical advantages, only few and small ME plants exist, mainl y because the MH process in its conventional design is rather complex . its stacked version however, which has been first introduced by Takada, can combine the low prime energy consumption of RO and tare inherent simplicity of the M.SF process . Multiple effect stack units can be operated with very small driving-forces .
Consequently MES processes can be designed comprised of a very high number of effects without increasing the top brine terciperature to figures above 115 -120 ยฐC .
The paper reports the results of experiments with different evaporator designs and the influence of brine distribution andd venting of non condensables on the performance of such MES-processes . Furthermore, conceptual design for waste heat utilisation and for vapor compression units will be discussed .