Synergistic Enhancement of Solar Thermal Energy Storage Using Al2O3 Nano-PCM and TiO2 Nanocoated Absorber Surfaces

Abstract

Heating is one of the basic services as well as leading to a green economy in the domestic and industrial sectors. In thermal energy storage, the integration of nanoparticles could improve heat absorption and retention capacity in solar thermal systems. Also boost photothermal conversion efficiencies by effective thermal conductivity enhancements and solar power utilization. A nano-enhanced phase change material (PCM) based on paraffin wax reinforced with aluminum oxide (Al₂O₃) was explored in this study. The nanoparticles with varied fractions of about 1–2 wt.% were developed for thermal conductivity enhancements and latent heat storage performance. The nanoparticle integrations are able to improve the heat absorption and thermal stability of the PCM, with an optimal concentration of 1.5 wt.% Al₂O₃ showing better thermal behaviors. The results of enhanced heat absorption of about 2467.9 W and latent heat storage were 2009.7 kJ. In addition, a titanium dioxide (TiO₂) nanostructured coating was integrated into the absorber surface to improve solar absorptance and reduce thermal emissivity. The synergistic integrations of TiO₂ nano-coated absorber surfaces with the optimized Al₂O₃-reinforced PCM could significantly improve photothermal energy conversion and heat storage capability, achieving a maximum outlet temperature of 90.7°C and a thermal efficiency of 79.5%. Hence, this study demonstrated a combination of nano-reinforced PCM and nanostructured absorber coatings, providing an effective materials-based option for enhancing thermal energy storage and solar power utilization in renewable energy systems.