INFLUENCE OF FINNED CYLINDER ORIENTATION IN A PERMEABLE WAVY CAVITY ON NANOFLUID HYDROTHERMAL PERFORMANCE UNDER A MAGNETIC FIELD FOR THERMAL ENERGY STORAGE

Objective: This study investigates the hydrothermal characteristics of water within the annular region of a thermal energy storage (TES) system featuring a wavy shell wall and a cylindrical tube equipped with three fins. The primary objectives are to analyze the impact of cylinder position and rotation on flow dynamics and thermal behavior, assess entropy generation under an inclined magnetic field and porous medium effects, and evaluate the role of copper nanoparticles in enhancing system performance. Methodology: The problem is modeled using dimensional governing equations and transformed into a coupled dimensionless partial differential framework. Numerical simulations are conducted via the finite element method in COMSOL, employing hybrid meshing and weak formulation for domain discretization. Grid independence tests and validation benchmarks ensure computational accuracy. Parametric variations in cylinder orientation, magnetic field inclination, and nanoparticle inclusion are systematically explored. Key Findings: Cylinder rotation and positional adjustments significantly influence velocity profiles and temperature gradients, and the inclined magnetic field amplifies flow resistance. Copper nanoparticles improve thermal conductivity, elevating the average Nusselt number by up to 18%. Entropy analysis reveals that thermal irreversibility dominates viscous effects, with Bejan number trends highlighting optimized configurations for minimizing energy losses. Applications: The findings demonstrate that TES systems with wavy geometries, finned tubes, and nanoparticle-enhanced fluids can achieve superior thermal efficiency and reduced entropy generation. This work provides actionable insights for designing advanced thermal storage solutions, particularly in renewable energy applications where intermittent sources like solar energy require robust heat management strategies.