Desalination of seawater using carbon-coated solar absorber in solar still

Desalination is a process of eliminating salt and other minerals from seawater which turns it to a safe usable water. This study showed the generation of clean water from seawater using carbon-coated solar absorber in two different solar still body colours which are transparent and black solar still, under direct solar exposure at approximately 1.2 kW/m2. The efficiency of carbon-coated solar absorber in the transparent and black solar still was computed, while the clean water collected was examined for its pH and salinity. Carbon-coated solar absorber in black solar still exhibit the highest efficiency at around 35.71%, where the pH and salinity of the collected clean water was substantially reduced to usable water at 6.55 and 62 ppm, respectively.

Theoretical Design of a Multilayer Based Spectrally Selective Solar Absorber Applied Under Ambient Conditions

With the increasing of global energy requirements and environmental problems, the use of solar thermal energy has attracted widespread attention. The selective solar absorption coating is the most important part of a solar thermal conversion device. At present, most of the coatings work well in a vacuum at a high temperature, while not stably in the air environment. Based on the high-temperature resistant and infrared-reflective properties of ITO, a multilayer film of SiO2/Si3N4/SiO2/ITO/Cr has been designed as a selective solar absorber. The genetic algorithm is applied to optimize the material and thickness selection for each layer. The results show that the optimized multilayer film could achieve a high solar absorptance up to 90% while keeping a relatively low infrared emittance around 50% for temperature change between 600°C and 900°C. All the materials composing this film have been tested before to be chemically stable at a high temperature up to 900°C in the air environment. It is also adaptive to different incident angles from 0° to 60°. The finite-difference time-domain method was also adopted to plot the energy density distribution for different wavelengths, which provided the underlying mechanism for the selective emission spectrum. The findings in this study would provide valuable guidance to design a low-cost selective solar absorption coating without the need for vacuum generation.