Incorporation of CoO Nanoparticles into Paraffin to Improve the Performance and Yield of Solar Still

Incorporating nano phase change materials (NPCMs) into the basin material helps improve the productivity and the evaporation rate in a solar still. Setting heat extraction rate as a standard, a comparative study was made with the yield of a single basin solar still by a phase change material (PCM) and NPCM. To counteract the low thermal conductivity of paraffin wax, metallic nanoparticles of cobalt oxide (CoO) were added. These CoO nanoparticles were found to be attractive for mixing with PCM to increase thermal conductivity. The impact of heat flux, flow rate and metal oxide particles on the flow and heat transfer behaviour of slurries was investigated. The X-ray diffraction (XRD) analysis showed the predominant peak (200) of CoO at 42.3°, with an average CoO nanoparticle size of 6 nm. The FESEM analysis revealed homogeneously aggregated spherical/platelet-shaped CoO nanoparticles ranging within 5–30 nm in size. Solar radiation increases linearly with time, reaching its maximum between 12:00 and 2:00 p.m. The use of NPCM increases the efficiency (12–25%) of the basin material due to its thermal properties and also the water output with an average yield rate of 3.5 L. Finally, the results indicate that the incorporation of CoO nanoparticles into paraffin wax increases the performance of the solar still and improves the water quality parameters.