A Novel Type of Thermal Solar Water Disinfection Unit

A novel type of solar thermal water disinfection unit is presented in this work. The system is safe and easy to use and can be built with basic tools and widely available materials. In the unit, water is disinfected by temperature increase up to the boiling point and output is controlled by the change in density. For employing the change in density to control the water output, a dimensioning procedure is suggested, giving the required height of the water reservoir, the heating section and the rising tube. Computational fluid dynamics simulations were performed to calculate the temperature increase in the rising tube, as it follows the temperature increase in the heated section. A model is presented to predict the water output and find a cost-effective configuration. For heating the water a simple flat plate absorber was designed and tested. With approximately 2 square meters of absorber area, up to 50 liters water output are expected per day in regions with high solar irradiation. The system was tested with contaminated water from the sewage and a reduction to zero coliform bacteria/100ml was obtained. In order to promote the distribution of the system, a construction manual is in the design process.