Simulation of thermal storage system integrated with U-shaped evacuated tube solar unit involving nanoparticle enhanced paraffin

This paper presents a novel approach to boost the productivity of U-pipe solar evacuated-tube system. The integration of a paraffin-nanoparticle mixture enhances the system's heat storage capacity significantly. Additionally, the incorporation of fins expedites the critical melting process. The study utilizes advanced numerical simulations conducted through the finite volume method. This integrated approach represents a notable progression in solar collector technology, offering potential for increased energy efficiency. To expedite the melting process, four fin configurations were taken into account. Six cases, integrating both loading nanoparticles and fin installation, were analyzed numerically using an implicit technique to demonstrate their impact. The required boundary conditions were determined through reference to previous experimental work. The numerical approach was validated using methods outlined in prior publications, resulting in satisfactory agreement. In the absence of fins, the dispersion of nano-powders leads to a 4.5 % increase in the liquid fraction (LF) after approximately 100 s, and a 2.9 % increase after about 400 s. On the other hand, when the optimal configuration of fins is incorporated, the LF experiences significant enhancements of approximately 138.71 % and 54.91 % at time intervals of 100 and 400 s, respectively. At 400 s, the introduction of ZnO nanoparticles and the incorporation of fins lead to temperature increases in the paraffin by approximately 0.5 % and 12.09 %, respectively. Meanwhile, at 250 s, the thermal performance, indicated by the LF value, exhibits a twofold improvement in the finned case compared to the finless case without nanoparticles.