Using metal foam and nanoparticle additives with different fin shapes for PCM-based thermal storage in flat plate solar collectors

This research focuses on employing heat transfer enhancement techniques as well as nanoparticles, porous metal foams, and extended surfaces, for the PCM-based thermal energy storage system of a flat plate solar collector. Numerical investigations are carried out for different combinations of the aforementioned techniques, with I-, Y-, and T-shaped fins as the extended surface. The mathematical model is developed with porous media equations, where nanoparticles are embedded in the PCM under the assumption of an equivalent single-phase medium. Results suggest that employing these techniques one by one augments heat transfer performances in terms of reduced melting time. The addition of both metal foam and nanoparticles in the straight wall (case A) reduces melting time by 85.16% when compared to the pure-PCM case, while a 84.38% reduction is reached if only foams are employed. The I-shaped fins (case B) are shown to have an impact too; they provide a 37.07% melting time reduction with only PCM, reaching 89.68% and 86.19% with nanoparticles with foams, respectively. This means that metal foams have a primary role in reducing melting time, where nanoparticles and I-shaped fins become helpful too. Furthermore, by considering all techniques together, the heat storage rate increases by an order of magnitude.