Energia solar térmica para fins de dessalinização: pesquisa e desenvolvimento de destiladores solares aplicáveis ao semiárido brasileiro

Abstract

In this study, a solar distiller model was developed and tested to meet the demand for desalinated water for human consumption in the Brazilian semi-arid region. The project involved analyzing mathematical models of solar incidence in the real environment and optimizing the design of the distillers to enhance radiation capture. A preliminary computational study was conducted to determine the most suitable geometry for local test conditions. To make the solar desalinator a viable technology for decentralized communities in the semi-arid region, the project prioritized system simplicity and the careful selection of construction materials that are economically accessible, chemically safe, and environmentally responsible. The proposed construction methodology aims for scalability of the distillers, utilizing a modular platform with precast lightweight expanded polystyrene concrete parts to provide adequate strength and thermal insulation. Tests using black paint as a photocollector demonstrated an accumulated distilled water production of 4.38 kg/m²/day, exceeding the reference system production by 72.1%. With only 4% commercial activated carbon as a photocollector, production reached 3.35 kg/m²/day, representing a 74.4% increase compared to the reference system. The average salt removal was approximately 99.4%. Another advantageous feature of the developed desalinator is its capability for semi-batch operation without affecting distilled water production, significantly reducing costs associated with process control systems. Due to its unique characteristics, the modular solar desalinator shows potential to become a socially relevant alternative, effective in mitigating the impacts of drought in the Brazilian semi-arid region.