Magneto‐Hydrothermal and Entropy Analysis of Double‐Diffusive Convection in a Nano‐Encapsulated PCM‐Suspended Elliptical Pipes Thermal Storage Tank: Impact of Exothermic Reaction

ABSTRACT PCMs store thermal energy during phase transitions without temperature changes, making them valuable for various thermal applications. When direct PCM use isn't practical, researchers have developed encapsulation methods as an alternative approach. Computational models can simulate various aspects including temperature patterns, species movement, fluid behavior, phase change regions, transport coefficients, energy utilization, and thermal performance metrics. This study explores the thermodynamic and flow characteristics of double‐diffusive convection in systems where nano‐encapsulated phase change materials are suspended in elliptical tube configurations, with additional consideration of exothermic chemical reactions. The investigation considers parameters including Rayleigh values (10 3 –10 5 ), Lewis number (0.1–10), Hartmann number (0–50), buoyancy proportions (1–5), NEPCM densities (0.01–0.035), relative melting points (0.1–0.9), Stefan number (0.1–0.9), magnetic field alignments (0°–90°), and Frank‐Kamenetskii number (0–2.5). Analysis shows that NEPCM concentration and magnetic field properties significantly affect both thermal‐hydraulic efficiency and entropy development. The complex relationships between parameters (Ra, FK, Le, Nz, ϕ , Ha) reveal their significant roles in determining heat transfer effectiveness and irreversibility formation.