Simulation of solar still processes of salt water

All around planet Earth, access to drinkable fresh water is a problem with increasing relevance, being its scarceness the origin of many diseases, namely in underdeveloped countries and a potential motivation to future conflicts. The present work focuses in the modelling of solar still systems of salt water, aiming at producing fresh water, having considered for that purpose four types of installations: passive solar still, passive solar still resorting to a regenerative system, active solar still and finally active solar still with a storage tank. For that, a modular simulation methodology has been used, developed in the integrated environment simulink/matlab, with the objective of characterizing the performance of those systems and testing their sensitivity to the variation of some parameters. It was also performed a comparison between the analysed technologies. The incident solar radiation in an arbitrary local on the Earth’s surface is simulated in a climate/environmental module that having tested the climate conditions in Porto Santo (33o30’ N, 16o20’ W) and Cape Verde (14o55’ N, 23o31’ W) for being places with an elevated potential for collecting solar energy, abundance in salt water and insufficient fresh water. The results show that the most influential parameters in the performance of the solar still units are the depth of the basin, the insulation thickness of the basin coating, the cover tilt angle, the number of sun collectors and the sun collectors tilt angle. Apart from these parameters regarding the installation, it has also been verified that the performance of the solar stills is highly dependent of the weather, through the solar radiation intensity and the environment temperature. It was also possible to acknowledge the increase production in the active solar still case in comparison to the passive case, as well as the increase in production and thermal efficiency resulting from the application of the regenerative system to the passive solar still unit.