Studies on hybrid solar still through waste heat recovery

Abstract

newlineWater is an indispensable requirement of human life and a key element for the existence and survival of human being. As per the United Nation World Water Development Report (2023), global water demand has been increasing at a rate of 1% per year since past 40 years, and expected to increase at the same rate, up to 2050. Although water covers approximately 71% of earth s surface, even then less than 1% of it is suitable and available for human consumption. More than 97% of water exists as saline water. The available freshwater is further shrinking due to man-made and industrial activities. Therefore, scarcity of usable water is knocking our doors as a serious global problem and the situation is getting worse continuously. Approximately six billion people, throughout the globe, are living in water stressed condition in the present scenario. That is why the sustainable development goal SDG-6 sets Clean Water as a global target. newlineMost of the global water supply comes from desalination of saline water. The conventional techniques adopted for this purpose are usually driven by fossil fuels and contravene SDG-7, Clean Energy target. Besides, these processes also incur adverse environmental impacts. High water and carbon footprint, global warming and depletion of fossil fuels are some of the major limitations. Therefore, sustainable desalination techniques are need of hour. newlineSolar still has emerged as a sustainable, economical and simple technique for water desalination. It utilizes solar energy for the purpose, making the process greener and cheaper. It also minimizes waste / rejections and works in an eco-friendly manner. However, its yield and efficiency are yet to match with other conventional commercial processes. Research is continued in order to improve its performance. Waste Heat Recovery is a key concept and established practice to improve the performance of various processes. A Solar dryer rejects approximately 75% of input energy in the form of waste heat. This heat can be potentially used to improve the p