Advanced Thermal Optimization of Solar Stills Using Encapsulated Phase Change Materials and Graphene Oxide Nanoparticles for Enhanced Energy Efficiency

ABSTRACT Solar desalination is a widely employed system that harnesses solar energy to produce drinking water. The key advantages of solar stills include that the generation of freshwater is a renewable energy‐based, eco‐friendly, and cost‐effective process. This sustainable approach addresses the critical need for clean water while minimizing ecological impact and offering economic benefits. In the solar still system, the configuration of the absorber plays a crucial role, as an ineffective absorber can lead to lower thermal performance and reduced water productivity. This investigation focuses on an absorber design that incorporates a tube container containing Phase Change Material (PCM) of paraffin wax. The encapsulation of PCM within the still enhances heat transfer and provides heat energy, especially during radiation fluctuations. Moreover, the thermal properties of the PCM were improved by introducing graphene oxide nanoparticles dispersed within. Three different concentrations of graphene oxide (0.3 wt%, 0.6 wt%, and 0.9 wt%) were investigated. It was explored that paraffin with 0.9 wt% graphene oxide nanoparticle demonstrates superior thermal performance compared to paraffin alone. Significantly, at a concentration of 0.9 wt%, the paraffin/graphene oxide nanoparticles showed increased water productivity, temperature, and still thermal efficiency by around 33.9%, 41.2%, and 68.7%, respectively.