Numerical investigation of pulsed heating effects on MgH₂ desorption kinetics and thermal efficiency in solid-state hydrogen storage

Magnesium hydride (MgH₂) offers high-capacity solid-state hydrogen storage, but it suffers from slow desorption due to its poor thermal conductivity. Here we model an MgH₂ composite containing 8 wt% expanded natural graphite (ENG), which raises the effective conductivity to 4.2 W.m⁻¹.K⁻¹. Finite element method (FEM) simulations performed in COMSOL Multiphysics compare a conventional constant radial heat flux with a stepwise ON/OFF (pulsed) regime. A 15-min ON/OFF cycle shortens the desorption time by 25 % from 60 to 45 min, keeps the wall temperature below 661 K, and leaves 3.4 kJ.m⁻³ of recoverable sensible heat, whereas constant heating leaves none. Raising conductivity above 4.2 W.m⁻¹.K⁻¹ offers little extra benefit because gas-phase transport and surface kinetics then dominate. Pulsed heating also exploits thermal-conductivity-evolution feedback (TCEF): MgH₂ converts to metallic Mg during each pulse, further boosting conductivity and accelerating subsequent pulses. Heat-flux sequencing, therefore, delivers faster, more energy-efficient hydrogen release without internal heat-exchanger hardware, highlighting a simple path to improved thermal management in MgH₂-based composite storage systems.