In the face of growing water scarcity worldwide, a team of researchers from the Indian Institute of Science (IISc) has developed a system that could help alleviate water shortages. This innovative thermal desalination system utilizes solar energy and has the potential to significantly increase the availability of clean, drinkable water in areas facing water scarcity.
Thermal desalination is a unique process that involves the removal of salt and impurities from water by utilizing heat to evaporate the water and subsequently condensing the resulting vapour to obtain fresh water. The heat required for this process can be generated through various energy sources, including electricity, fossil fuels, or renewable energy such as solar power.
The team at IISc has successfully designed a solar-powered desalination unit that surpasses its predecessors in terms of energy efficiency, cost-effectiveness, and portability. This system incorporates the same working principle as solar stills, where solar energy is employed to evaporate saltwater in large reservoirs, and the condensed vapour collected on a transparent roof is gathered as fresh water.
Assistant Professor Susmita Dash from the Department of Mechanical Engineering explained that the newly developed system is particularly convenient for deployment in areas with limited access to continuous electricity. It consists of a reservoir of saline water, an evaporator, and a condenser enclosed within an insulating chamber to minimize heat losses to the surrounding air.
By utilizing solar thermal energy, a small volume of water wicked into the evaporator undergoes evaporation. The evaporator's textured surface leverages the capillary effect of microscale textures, allowing the liquid to be drawn into narrow spaces, thereby enhancing the system's energy efficiency. The research team conducted experiments to optimize the wicking process by varying groove dimensions, spacing, and surface roughness.
To prevent the formation of a water film during condensation, the researchers designed a condenser with alternating hydrophilic and superhydrophobic surfaces. This innovative approach ensures efficient condensation and maximizes water yield. The system is intelligently designed to trap and harness the heat released during condensation, further reducing the amount of solar energy required. This captured heat is then utilized to warm up the saltwater in a separate evaporator located behind the condenser, significantly enhancing the overall efficiency of the system.
Moreover, the system has been designed to adapt to the sun's shifting positions throughout the day, ensuring optimal performance. It is capable of effectively desalinating seawater, groundwater with dissolved salts, and brackish water.
The focus of the research team is scaling up the system, improving its durability, and increasing the volume of drinking water produced. By further refining this technology, the researchers aim to make a substantial contribution towards addressing water scarcity and ensuring access to clean drinking water for communities around the world.
