Aplicação de carbeto de silício como material fototérmico em sistemas de dessalinização solar

Abstract

In the Brazilian semi-arid region, during dry periods, water availability decreases considerably, which makes it essential to use water from tanker trucks and wells, which often have high levels of salinity, making it difficult to use them in various activities. In this scenario, desalination emerges as a promising alternative. To improve the efficiency of desalination plants, photothermal materials have been widely used to optimize heat transfer. This research investigated the thermal performance of asymmetric pyramid solar desalination plants, with the addition of silicon carbide (SiC) as a photothermal material, aiming to increase water productivity. Three desalination plants were analyzed simultaneously, using brackish water from an artesian well located in the rural area of Alagoa Grande/PB. Initially, SiC was used in suspension, and later mixed with black paint at concentrations of 10% and 20%. Different water depths (1 cm, 2 cm and 3 cm) were tested, and the experiments were repeated on days with different weather conditions. To observe the influence of the water layer thickness under the same climatic conditions, experiments were also carried out varying the layer thickness on the same day (1 cm, 2 cm and 3 cm), taking into account the area of the desalination tray. The water was characterized by means of physical-chemical analyses performed before and after the desalination process. In addition, a thermal analysis was performed to evaluate the temperatures during the process and their influence on the efficiency and productivity of the desalination plants. The photothermal material was characterized using the techniques of X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Particle Size Distribution (PGD) and Scanning Electron Microscopy (SEM). The XRF analysis allowed the identification of the elemental composition of SiC, with emphasis on a percentage of silicon greater than 68%. The XRD technique revealed that SiC has a predominantly single-phase crystalline structure. FTIR demonstrated the characteristic bands of SiC, while DG analysis indicated an average particle diameter of approximately 1.38 μm. SEM was essential for the analysis of the SiC microstructure. Finally, the thermal analysis was complemented by thermographic camera images, which enabled the comparison of temperatures on the surface of the solar desalinizers.