Korean Scientists Light a 'Green Light' for Solving Drinking Water Shortages in the Developing World

Korean Scientists Develop Solar-Powered Desalination Device
No Electricity Needed, 90% Efficiency Achieved with 3D Printing
Expected to Aid Water-Scarce Regions in Africa and the Middle East

[Asia Economy Reporter Kim Bong-su] Korean scientists have delivered good news to countries in Africa and the Middle East suffering from severe drinking water shortages. They have developed a seawater desalination device that uses solar heat, requiring no electricity supply, is cheap and fast to produce with 3D printing, and has an efficiency of 90%.

Ulsan National Institute of Science and Technology (UNIST) announced on the 22nd that it has developed a new seawater desalination device that distills seawater using solar heat to convert it into drinking water. The research team led by Professor Jang Ji-hyun of the Department of Energy and Chemical Engineering developed a Solar Evaporator that can effectively absorb solar heat. When this evaporator is made in a size of 1㎡, it can produce more than 1.6 kg of freshwater per hour. In the Solar Evaporator, pure water from the seawater drawn in emerges as vapor, while salt and other residues remain in the evaporator. The evaporated water can be condensed again to be used as drinking water.

The research team designed the Solar Evaporator to maximize light absorption by effectively trapping sunlight. It was designed as a multi-reflection system so that reflected light can be reabsorbed, increasing the amount of light (heat) absorbed by the photothermal absorber. When the heat absorbed by the photothermal absorber meets seawater, evaporation occurs. As the photothermal absorber absorbs more heat, the amount of freshwater obtained increases by about 10%.

Additionally, the device effectively prevents salt accumulation on the photothermal absorber, extending its lifespan by more than three times. Salt buildup shortens the lifespan of the absorber. To prevent this, the absorber was made from two types of materials. The upper part uses a hydrophobic material that repels seawater like a lotus leaf, while the lower part, which is in direct contact with seawater, uses a hydrophilic material. Salt accumulated at the bottom is washed away by seawater.

The developed Solar Evaporator achieves a vapor conversion efficiency close to 90%. Through heat transfer analysis and additional experiments, the research team identified the cause of this ultra-high efficiency: a vapor film formed on the surface of the photothermal absorber reduces heat loss.

Soorop Shalle, a first author and PhD candidate in the Department of Energy and Chemical Engineering at UNIST, explained, “Through this research, we mathematically proposed a new heat transfer model essential for Solar Evaporator research. Existing carbon-based photothermal absorbers had a limitation of 70% to 80% efficiency in converting solar heat into vapor, but by controlling the shape and thermal physical properties of the absorber, we achieved an efficiency close to 90%.”

The device was designed to absorb solar heat more effectively than before, increasing freshwater conversion and improving durability by more than three times. It can also be easily manufactured using 3D printing. The research team expects it to provide significant help to developing countries facing drinking water shortages.

The research results were published on the 4th in the international journal Advanced Materials. It was selected as a frontispiece paper and is scheduled for formal publication.

This content was produced with the assistance of AI translation services.