Magneto-convective transport and phase-change dynamics of NEPCM nanofluids under the influence of a rotating magnetic field

Purpose This paper aims to investigate the unsteady magneto-convective transport and latent heat evolution of nano-encapsulated phase change material (NEPCM) suspensions within an enclosure subjected to rotating magnetic field (RMF) excitation. Design/methodology/approach A robust finite element framework is used to evaluate the complex coupling between buoyancy-driven natural convection and electromagnetic torque. The dimensionless governing equations are solved across a wide parametric space, including NEPCM volumetric concentrations (0 ≤ ϕ ≤ 0.05), Rayleigh numbers (105 ≤ Ra ≤ 107), Hartmann numbers (5 ≤ Ha ≤ 50) and dimensionless rotation frequencies (4 ≤ ξ ≤ 32). Findings Increasing the NEPCM concentration from 1% to 5% yields substantial gains in thermal transport and energy storage, highlighted by a 555.8% surge in latent energy utilization. This latent heat absorption drives maximum enhancements of 26.5% in flow circulation strength and 28.8% in overall heat transfer performance. Furthermore, the optimum rotational frequency of the magnetic field must be tuned depending on whether the primary thermal objective is rapid heat dissipation or maximum latent energy storage. Research limitations/implications The numerical model is restricted to two-dimensional laminar flow with constant thermophysical properties and neglects induced magnetic fields and three-dimensional effects. Consequently, the present results are most applicable to low magnetic Reynolds number flows. Practical implications The findings provide useful design guidelines for the active thermal management of electronic cooling systems, latent heat thermal energy storage devices, and other applications requiring non-mechanical control of convective heat transfer through RMFs. Originality/value This work presents a comprehensive numerical investigation of NEPCM nanofluids subjected to RMF excitation. It demonstrates how magnetic-field rotation can actively manipulate flow structures, heat transfer characteristics and the spatial distribution of phase change while revealing the strong coupling between magnetic forcing, buoyancy and latent heat transport.