Design, Construction and Preliminary Evaluation of a Vertical Diffusion Still for Solar Thermal Assisted Desalination

This paper presents an overview of the solar assisted desalination project, which began in Fall 2015 and culminated in the design of a pilot plant solar assisted desalination of seawater in Qatar. While seawater desalination... [ view full abstract ]

This paper presents an overview of the solar assisted desalination project, which began in Fall 2015 and culminated in the design of a pilot plant solar assisted desalination of seawater in Qatar. While seawater desalination is an energy intensive process often associated with sustainability issues and environmental impacts, this project aimed at developing a solution that minimizes environmental consequences of conventional desalination by using solar energy. Earlier experimental work on water heating showed that flat plate solar collectors that implement improved geometric patterns have potential to heat water to temperatures close to that required for desalination. To this end, a single-effect vertical distiller was developed with the detailed design focused on production and ease of maintenance. The heat collection part was designed to provide, continuously, the hot water to the distillation unit and circulation of air in the two plates was maintained by natural convection. A pilot desalination plant on was designed, fabricated and tested to demonstrate the distillation process. Parametric investigations of the design and operation conditions of the single effect vertical distillation concept was carried out. In the preliminary investigation, grey water was used to demonstrate the distillation effect. Productivity of the proposed system at different times were determined. It was found that productivity increased with an increase in the temperature of the grey water feed, the thickness of the diffusion gap between partitions, and the feeding rate of grey water. Tests on the distillate shows differences in comparison to the feed grey water. Obtained results demonstrate that solar desalination could be a viable option if auxiliary water heating is provided in order to reach the temperature ranges required for seawater desalination. The paper also discusses gain ratio, operating temperature, materials of construction, operation and maintenance of the system, and associated problems. Attempts to identify areas of development and improvements are also presented with specific reference to the proposed solar assisted seawater desalination.

Acknowledgements

This research was made possible by a NPRP award NPRP 5-161-2-053 from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.