Theoretical assessment of a solar still system equipped with Nano-phase change materials

Regarding water scarcity in recent decades, solar stills due to their environmental compatibility and economic viability received more attention. Through the current study, the performance of weir-type cascade solar still equipped with different phase change materials (PCMs) especially Nano-PCMs is evaluated. The utilized phase change materials are Stearic acid, Paraffin, and some kinds of PCMs that are enhanced with Nanoparticles of different materials. The Nano-enhanced PCMs are consisted of nePCM I (Paraffin+TiO2), nePCM II (Paraffin+CuO), and nePCM III (Paraffin+GO). The novelty of the present work can be attributed to the exegetic and energetic analysis of cascade solar still equipped with Nano-enhanced PCM as well as investigating the effects of climatic parameters on the performance of the system. Regarding the results, in brackish water mass flow rate of 0.07 and 0.4 kg/(m(2).min), the system equipped with nePCM II has the energy and exergy efficiencies of 63.55, 6.4181, 56.79%, and 5.387, respectively. Moreover, for the mass flow rate of 0.2 and 0.3 kg/(m(2).min) the nePCM I show higher energy efficiency compared to others. The maximum distilled water production belongs to nePCM II in the mass flow rate of 0.07 kg/(m(2).min), which is 9.28 kg/(m(2).hr). Besides, the results showed that at the ambient temperatures lower than 29 degrees C, the system equipped with Stearic acid has better performance from an energetic and exergetic point of view. Finally, the best Azimuth angles for the system in the presence of different PCMs presented.