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

Engineering Thermodynamics

Involved People:
Carlos. Infante Ferreira

Facilities used: