Solar thermal energy combined with humidification–dehumidification process for desalination brackish water: Technical review

Water scarcity has become a chronic problem aggravated by climate change. One third of the worldʹs population already lives in areas suffering moderate to high water stress; some 1.5 billion people lack ready access to drinking water. Desalination is in the course of becoming a major source of fresh water by tapping into the vast reserves of seawater and brackish water. Large scale desalination plants use either thermal or membrane processes which consume a great deal of energy. Economic implications of large energy requirements coupled with environmental concerns about carbon emissions spurred a growing interest in developing desalination processes that use renewable energy sources. Among these processes the humidification dehumidification (HD) of air, using solar energy, is a simple technology particularly suited for regions in developing countries where there is very low infrastructure and unskilled manpower. s paper we review various technologies under investigation to desalinate saline water through HD of air and using solar thermal energy. A particular emphasis will be put on the various types of solar water heaters as well as the various designs of solar air heaters.