Scale-up of a solar-driven modular desalination device for remote areas

More than 700 million people around the world suffer from severe water scarcity. Desalination is one of the most promising solution to contrast this problem. In particular, passive desalination is considered the most suitable expedient to mitigate water scarcity where this problem is striking the most, namely in remote areas. These passive technologies, although historically considered energy-intensive, are particularly appealing when powered by renewable sources such as solar energy. The goal of this thesis is then to develop a scaled-up version of the innovative passive solar high-yield seawater desalination technology, developed at Politecnico di Torino. The latter is able to operate without the use of any active components and it is based on a smart combination of low-cost materials. The work is organized according to different sections. First, an overview of the most common active desalination techniques operating at industrial level is addressed. Subsequently, the state-of-the-art of technologies able to passively produce freshwater is reported. Among these, the scaled-up version of the proposed passive device shows the best performance relying on a multi-stage process that enables latent heat recovery. Then, the design and prototyping activities have been extensively discussed. The guidelines imposed by a modern worldwide contest (namely Oman Humanitarian Desalination Challenge) have been followed to develop the device. In detail, a cross-flow configuration has been exploited to overcome the limited capillary-driven water transport on each hydrophilic layer exasperated by the increased size of the unit. Numerical simulations are carried out by means of COMSOL Multiphysics software to figure out the best configuration. Finally, results of an extensive in-field experimental campaign, conducted on the roof of Politecnico di Torino, are reported and discussed. The latter are in agreement with the model predictions obtained by the already developed theoretical approach. The described promising results lead the proposed desalination technology one step closer towards public distribution.