Nanofluid unsteady heat transfer in a porous energy storage enclosure in existence of Lorentz forces

•Time dependent heat transfer of NEPCM during discharging process is investigated.•Macroscopic approach is employed for numerical simulation.•Influence of Lorentz forces on discharging rate is investigated.•Discharging time reduces with rise of Hartmann number. In current article, nanofluid time dependent heat transfer under the influence of Lorentz forces during discharging process is simulated by means of FEM. In order to overcome the limitation of PCM, NEPCM has been utilized. CuO and water are employed as nanoparticles and PCM. Brownian motion role is taken into consideration to estimate nanofluid characteristics. Graphs are illustrated as isotherm, solid fraction and stream line contours. Results reveal that discharging rate improves with augment of Lorentz forces. As Hartmann number augments, solid fraction profile will be converged in lower time. Dispersing nanoparticles has significant impact on phase change front.