Employing convex shape absorber for enhancing the performance of solar still desalination system

This paper presents an experimental study for new solar still (SS) called convex SS. The convex SS has been tested at different convex heights, different wick materials, with Nano (Ag) black paint, and with Nano phase change material (paraffin wax + Ag). The results showed that, at 15 cm convex height and jute wick the convex SS showed 54% superior productivity than conventional SS. Besides, the data illustrated that, increasing the convex height increases the daily productivity of the convex SS till reaching the peak at 15 cm. Then, the yield started to decrease again at convex height larger than 15 cm. additionally; the jute wick showed higher performance with convex SS compared with cotton wick. The thermal efficiency of convex SS at 15 cm height showed about 41.2% and 40.8% for jute and cotton wicks, respectively. Furthermore, adding Ag nanoparticles to the black paint used to paint the convex surface increased the daily productivity to be 72% over conventional SS. As well, using thermal energy storage material (paraffin wax) mixed with Ag nanoparticles (2.5 wt.%) and Nano black paint enhanced the daily productivity of the convex SS to be 112% higher than conventional SS. So, it can be concluded that using Nano PCM enhanced the productivity of convex SS by about 40%. The economic analysis indicated that, the price per liter of fresh water is estimated to be 0.028 and 0.025 $/ l for conventional SS and convex SS, respectively.