Impact of fin number and nanoparticle size on molten salt NanoPCM melting in finned annular space

Nanoenhanced phase change materials (NEPCMs) have attracted substantial interest in recent times due to their enhanced thermal properties and improved rates of heat transfer. When employed within a concentric enclosure, they exhibit remarkable potential for efficient and effective thermal energy storage, with applications spanning building insulation, electronics cooling, and solar energy storage. The aim of this study is to perform an extensive numerical investigation of the melting process of NEPCMs confined within a finned eccentric annulus, which serves as a representative model for thermal energy storage systems. The PCM considered is potassium nitrate that is dispersed with nanoparticles of Titanium dioxide, Aluminum oxide and single walled carbon nanotubes. An investigation has been conducted to assess the influence of different parameters, such as the number of fins, Rayleigh number, nanoparticle volume concentration, and nanoparticle size, on the phase change and heat exchange phenomena. The melting rate is found to be proportional to the number of fins and heat transfer enhancement of 56.86% is observed for eight finned case. The average melt fraction experiences a substantial increase of up to 35.35% when the particle volume fraction is increased to 4%. The decrease in particle size enhances the NEPCM melting fraction up to 46.03%.