Thermal performance assessment by cerium oxide nano-enhanced coating on evacuated tube solar collector absorber tubes

• ETSC performance enhanced using CeO 2 nano-coatings via spray pyrolysis. • 0.8 μm CeO 2 coating improved heat absorption by 47.2 % over black paint. • Coating reduced heat loss by 41.9 %, boosting thermal retention efficiency. • Achieved 65.6 % thermal and 11.2 % exergy efficiency with CeO 2 coating. • CeO 2 nano-coating offered a 63.5 % overall efficiency improvement for ETSCs. This study explores the enhanced performance of an evacuated tube solar collector (ETSC) through the application of nano-engineered coatings designed to maximize heat absorption and retention. While ETSCs are renowned for their solar heating efficiency, challenges such as heat loss and vacuum degradation can compromise long-term performance. To address these, the absorber tube was initially coated with black matt paint to optimize solar absorptivity while reducing emissivity. Further performance improvements were achieved by integrating a Cerium oxide (CeO 2 nanoparticle coating, applied using spray pyrolysis at 80°C, with thicknesses ranging from 0 to 0.8 μm. Remarkably, the 0.8 μm CeO 2 -coated absorber exhibited a 47.2 % increase in heat absorption and a 41.9 % reduction in heat loss compared to the standard black-coated tube. The nano-enhanced coating also achieved thermal and exergy efficiencies of 65.6 % and 11.2 %, respectively, resulting in an impressive overall efficiency improvement of 63.5 %. These results highlight the transformative potential of a 0.8 μm CeO 2 nanoparticle coating in elevating the thermal performance and sustainability of ETSC systems, paving the way for more effective solar energy utilization.