2014 Spring: Fresh water production using direct contact condensation

Many regions in the world depend heavily on expensive desalinated water for its consumption, in
particular
tropical areas. Current mainstream desalination technologies (Reverse Osmosis and Multi-
Stage Flash Evaporation) can be considered to be quite energy intensive and thus costly. Today’s 

challenge is to design a desalination system that could run with local available renewable energy and 
provide affordable fresh water, even in the most arid environments.
 
The energy resource that has serious potential to provide a solution is the ocean. The oceans receive 
70% of all sunlight that falls on the Earth, making them the largest solar collector. The sun’s energy 
warms the surface water, while the deep ocean water remains cold, which creates the ocean’s naturally 
available temperature gradient, or thermal energy. This year-round available thermal energy present in 
the tropics could drive seawater desalination and enable fresh water production in an economic and 
ecological manner. 
 
The selected configuration for desalination is a direct contact condensation process. It makes use of the 
relative high humidity air in the tropics and condenses it against a cooled fresh water loop in a packed 
bed column. The cold seawater is used in an external heat exchanger to cool the fresh water loop. Out 
comes fresh water and dry air without the need of energy intensive equipment. 
 
Possible research topic 
Analysis of the desalination method in transient conditions (e.g. varying air humidity, temperature) 
considering the relation of energy requirements vs. fresh water production and validation of the 
theoretical model with an experimental set?up

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