Solar Concentration and Membrane Distillation coupling: System Model and Case Studies

Freshwater access issue has grown dramatically over the years due prominently to population increase, climate change, pollution. The simultaneous presence of freshwater scarcity, salt water reserves and high insolation in several locations in the world suggests the use of solar energy to feed desalination process. Since these locations are often situated in remote and underdeveloped regions it is crucial to utilize stand-alone, simple and economical technologies. A membrane distillation process coupled with a solar concentrator can meet these requisites. In this Thesis work it is proposed the model of a solar desalination system that includes a solar parabolic-dish concentrator (Trinum by INNOVA), a back-up conventional boiler, a sensible heat thermal storage, and a membrane distillation lab unit (by AQUASTILL), to perform simulations of operation in three different geographical locations: Turin (ITA), Palermo (ITA) and Abu Dhabi (UAE), and to provide a basic proof of concept. Simulink software was used to construct the system model, taking advantage of the software ability to run dynamic simulation and to handle results conveniently, while PVGIS database website provided the input climatic data. The membrane distillation lab unit model was validated comparing computational results with empirical data from experiments conducted on the physical device in Polytechnic of Turin DIATI department. The simulated period spanned over a year to compute the most relevant quantities involved in the system operations, used to assess the system freshwater annual yield and the solar on total energy fed factor, representing the renewable share of the energy involved in the freshwater production over one year. The results show promising performances: in all the three case studies the solar share is larger than 70%, and the Abu Dhabi case study reaches the maximum of 93%. It is possible to take further steps to advance the work, considering and implementing commercial size membrane distillation devices, to provide a better insight on system concept validity, and performing economic feasibility analysis.