Work

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

Year: 2025

Type: article

Abstract: Magnesium hydride (MgH2) offers high-capacity solid-state hydrogen storage but suffers from slow desorption because of 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.

Source: Applied Energy

DOI: 10.1016/j.apenergy.2025.126690