Design of an autonomous solar desalination plant using vacuum membrane distillation, the MEDINA project

• Design of a completely autonomous desalination plant.
• Coupling the vacuum membrane desalination module with solar energy.
• Choosing of the main equipment of the process (solar collector, PV cells, membrane module).

The unit presented in this paper is designed to provide a high quality of potable water in remote coastal areas with bad infrastructure and without a network connection. The installation is designed completely autonomous; indeed the only source of energy is the sun.The electrical energy required to operate the system is generated by means of a photovoltaic cells field, and heating the sea water is provided by a solar collector field. Technical-economic study of different types of solar collectors led to the choice of selective flat plate collectors. Energy optimization of the arrangement of these collectors allowed us to choose a field comprises 7 cascades each having 5 collectors connected in series. The auxiliary electric power which is necessary for the pumps functioning is provided by the PV panels. The energy performance of the desalination unit is enhanced by a recovery of the latent energy of condensation. The adopted hollow fiber module is formed of 806 fibers and has with exchanged area of 4 m2. A plate heat exchanger ensures the heat exchange between the collectors and the pilot plant. A tubular condenser is used to condense the steam produced. The vacuum is provided by a peristaltic pump.