Floating MD plant wins Munich desalination challenge

A floating membrane distillation design was this year’s winner of the TUM DeSal Challenge, an initiative of the department of thermodynamics at the technical university in Munich (TU München), Germany, and open to school and university students.

After more than a year of intensive preparation and two exciting competition days on 28- 29 June 2013, the winner of the € 1,500 prize was team NanoSystem. Second place went to team Wasserbrennerei with a vacuum distillation plant, while the team Drink of Water was ranked third.

Raphael Wagensonner from NanoSystem succeeded in impressing the jury with his desalination plant, which floats on the sea surface and uses the sun’s energy for thermal membrane distillation of salt water. The plant gained overall the most points in the disciplines Amount of Water & Water-quality, Cost Planning, Maintenance and Degree of Innovation.

The construction consists of a stainless steel tank in which a PTFE-membrane is mounted a few millimetres above the floor of the tank. The salt water is right above the membrane and is heated by an absorber.

The copper absorber is painted black on the sun-facing side, leading to a thermal conversion of the solar energy. The movement of waves is used for circulation of the salt water on the membrane.

Powered by the temperature difference between the warm copper absorber and the bottom, cooled by the seawater, vapor diffuses through the impermeable membrane. At the cold base, the water vapor condenses and is collected in a centrally located runoff.

Team Wasserbrennerei produced the cleanest water and the biggest amount during the two competition days. With their vacuum distillation plant they not only took second place but also won the prize for market relevance.

As well as taking part in the TUM DeSal Challenge, the eight participating teams also had the chance to visit the TUM DeSal Conference and listen to lectures from experts from Germany and Greece.