Effect of fins and silicon dioxide nanoparticle black paint on the absorber plate for augmenting yield from tubular solar still

The present study aims at enhancing the yield of tubular solar still (TSS) by employing fins and coating the absorber plate. We doped the SiO₂ nanoparticles into black paint at the weight concentration ranging from 10 to 40%. The solar still was tested in a bright sunny climatic condition of Chennai, Indian (lat. 13° 08′ N and long. 80° 27′ E). Under transient heat flux conditions, water, basin, and TSS glass temperatures with and without fin were measured. The rate of heat transfer by convection between the water and absorber plate was increased. Results revealed that the basin and water temperatures were improved by 10.49% and 10.88%, respectively when using black paint with SiO₂ nanoparticle in the concentration of 20%, coated on the absorber plate compared to that when using the ordinary black paint, while using the fins on the absorber plate enhanced the potable water produced by 55.18% when using 20% SiO₂ nanoparticle compared to that of conventional TSS. The cost per liter of water produced using the flat and finned absorber coated using 20% SiO2 nanoparticle in black paint is found as 0.0187 and 0.012 $/L respectively.