Effect of water depth on a novel absorber plate of pyramid solar still coated with TiO ₂ nano black paint

In this study, the absorber plate of a new pyramidal basin type solar still is coated with TiO ₂ nanoparticles doped in black paint on the basin to analyze the performance under the various depth of water. Water depth is varied from 1 cm till 3.5 cm on a basin area of 0.25 m ² which is almost equal to the area of the glass cover. Instead of using other sensible storing materials inside the basin which probably increase the weight, a novel solar still with the absorber plate coated with TiO ₂ nanoparticle mixed with black paint to improve the performance. Experimental results revealed that the use of TiO ₂ nanoparticle in black paint improved the water temperature by 1.5 °C than that of absorber without nanoparticle. Similarly, the yield improved during the sunshine hours rather than the off shine hours. With increased depth of water in the basin, the water temperature is minimum which simultaneously resulted in the lower yield on absorber without coating whereas the yield from the still improved by 12% at maximum water depth using coated absorber plate. The accumulated yield from the solar still absorber plate with and without coating was found to be 6.6 and 6.2 kg/m ² respectively at 1 cm water depth. TiO ₂ nano black paint coated pyramid solar still improves the distilled yield by 6.1% as compared to the conventional basin type pyramid solar still. Similarly, the values of instantaneous efficiency based on operational and climatic parameters using linear and non-linear were determined. From the cost breakdown analysis, it is found that the present system is feasible as compared to the conventional pyramid solar still without coating.