Energy storage hydrothermal and entropy analysis of micro-polar Nano-encapsulated phase change materials under the effect of exothermic reaction and external magnetic field

In recent years, the growing demand for electricity has underscored the need for efficient energy storage solutions. This study investigates the energy storage, hydrothermal performance, and entropy analysis of micro-polar nano-encapsulated phase change materials (NEPCMs) under the influence of an exothermic reaction and an external magnetic field. The novelty of this work, which focuses on energy storage applications, lies in the use of a novel geometry and a range of highly effective parameters. The numerical study explores the physical interactions between heat and mass transfer, considering a wide range of parameters, including the Rayleigh number (10 3 ≤Ra≤ 10 5 ), Lewis number (0.1 ≤ Le ≤ 10), buoyancy ratio (1 ≤ Nz ≤ 5), Hartmann number (0 ≤ Ha ≤50), magnetic field inclination angle (0 o ≤ γ ≤ 90 o ), Frank-Kamenetskii number (0 ≤ FK ≤ 2.5), NEPCM concentration (0.01 ≤ ϕ ≤ 0.035), fusion temperature (0.01 ≤ θ f ≤ 0.035), Stefan number (0.1 ≤ Ste ≤ 0.9), and aspect ratio (0.5≤AR≤1.5). The results demonstrate that increasing Ra enhances the average Nusselt number (Nu av ) by up to 429.9% and the average Sherwood number (Sh av ) by up to 206%, while increasing the total entropy generation (S total ) by up to 13,014%. Increasing FK reduces Nu av by up to 27.8% but increases Sh av by up to 42.7%. The Le, Nz, and ϕ significantly impact the hydrothermal performance and entropy generation, with Nu av increasing by up to 36.3% and Sh av decreasing by up to 5.6% as ϕ increases. The Ha substantially reduces Nu av and Sh av by up to 62.3% and 31.2%, respectively, while the γ exhibits a non-monotonic behavior with an optimal angle around 60°. The most prominent conclusions highlight the complex interplay between various parameters, with Ra, Le, Nz, and Ha having substantial effects on the hydrothermal performance and entropy generation. The findings provide valuable insights for optimizing the design and operation of energy storage systems based on micro-polar NEPCMs.