Thermal and heat storage performance evaluation of a parabolic trough solar thermal collector featuring phase change material composite and hybrid nanofluid

Abstract The solar thermal system configured with phase change materials (PCM) won better thermal efficiency and reduced fossil fuel use. However, variations in solar radiation cause reduced thermal performance and lead to poor heat transfer efficiency behaviour. Current research intends to study the thermal performance of solar thermal collectors hybridized with hybrid nanofluid composed with 50: 50 ratios of copper oxide and alumina nanoparticles via ultrasonication process, and varied ratios of paraffin/salt hydrate mixture are used for thermal storage. The system is operated under 4 LPM of hybrid nanofluid with 70:30, 60:40, and 50:50 ratios of paraffin: salt hydrate mixture and its actions on thermal performance and heat storage capacity behaviour are studied. Investigated results are compared with solar thermal systems operated without hybrid nanofluid (baseline) and PCM. An impact of PCM with hybrid nanofluid recorded superior thermal performance and superior heat storage capacity than base line. Moreover, the system operated with the 60:40 PCM ratios of paraffin: salt hydrate mixture and hybrid nanofluid exhibited the best performance. Specifically, the outlet temperature reached 88.6°C, and the heat storage capacity increased to 1215.4 kJ. The pressure drop was recorded at 3.9 kPa, while the heat transfer rate reached 2677.2 W, and additionally, the thermal efficiency and average thermal efficiency were observed at 67.3%. This study offers a promising strategy for enhancing the efficiency of PTC solar thermal energy systems with the PCM and nanofluid conditions.