[Paper Review] Coupling Thermal Integration of a Solid Oxide Fuel Cell with a Magnesium Metal Hydride Tank

Evangelos I. Gkanas, Sofoklis S. Makridis+1 more|arXiv (Cornell University)|Dec 2, 2014

Hydrogen Storage and Materials3 citations

TL;DR

This study proposes a thermal integration strategy coupling a solid oxide fuel cell (SOFC) at 700 °C with a cylindrical magnesium hydride (MgH₂) tank to enhance hydrogen desorption. Using a 3D validated mathematical model, it evaluates four heating scenarios—external heater, SOFC radiation, SOFC cathode exhaust air, and a hybrid approach—demonstrating that exhaust air and hybrid heating yield uniform temperature distribution and improved desorption capacity.

ABSTRACT

The dehydrogenation behaviour of a cylindrical Mg metal hydride tank is simulated and examined in the case where the tank is thermally coupled with an operating Solid Oxide Fuel Cell (SOFC) at 7000C. A three-dimensional validated mathematical model is utilized to simulate the hydrogen desorption from a cylindrical Mg hydride tank. Four scenarios are simulated: a base case where the heat source for the desorption process is an external heater surrounding the tank. The second case examines the effect of the radiation heat transfer from the SOFC to the metal hydride as a possible heat source for the desorption procedure. The third scenario uses the exhaust air from the SOFC cathode as the heating source which is driven to the hydride and the fourth scenario is a combination of both the exhaust air from the SOFC cathode and the external heater as the heat source for the desorption. According to the results, the exhaust air from the SOFC and the combination of external heater and the exhaust heat have a uniform temperature distribution within the tank and enhance the desorption capacity.

Motivation & Objective

• To investigate thermal integration strategies between a solid oxide fuel cell (SOFC) and a magnesium metal hydride (MgH₂) tank for improved hydrogen storage and release.
• To address the challenge of inefficient and non-uniform heating in metal hydride tanks during hydrogen desorption.
• To evaluate alternative heat sources—SOFC radiation, cathode exhaust air, and hybrid systems—beyond conventional external heating.
• To optimize desorption performance through thermal management using waste heat from the SOFC.
• To validate the 3D mathematical model against experimental data for accurate simulation of hydrogen desorption dynamics.

Proposed method

• Development and validation of a 3D transient mathematical model for hydrogen desorption in a cylindrical MgH₂ tank.
• Simulation of four heating scenarios: (1) external heater only, (2) SOFC radiation as heat source, (3) SOFC cathode exhaust air as heat source, and (4) combined external heater and exhaust air.
• Incorporation of heat transfer mechanisms including conduction, convection, and radiation within the tank and between SOFC and hydride components.
• Use of energy and mass conservation equations to model the thermodynamics of hydrogen release from MgH₂ under varying thermal boundary conditions.
• Application of boundary conditions based on SOFC operating temperature (700 °C) and exhaust air temperature and flow rate.
• Validation of the model against experimental data to ensure accuracy in predicting temperature distribution and desorption kinetics.

Experimental results

Research questions

• RQ1 How does coupling the SOFC with a MgH₂ tank via thermal integration affect hydrogen desorption uniformity and rate?
• RQ2 What is the impact of using SOFC radiation as a heat source on the temperature distribution within the MgH₂ tank?
• RQ3 Can SOFC cathode exhaust air serve as an effective and uniform heat source for hydrogen desorption from MgH₂?
• RQ4 How does combining external heating with SOFC exhaust air improve desorption performance compared to single-source heating?
• RQ5 To what extent does thermal integration reduce the need for external energy input in MgH₂-based hydrogen storage systems?

Key findings

• The use of SOFC cathode exhaust air as a heat source results in a more uniform temperature distribution within the MgH₂ tank compared to external heating alone.
• The hybrid heating approach—combining external heater and SOFC exhaust air—achieves the most uniform temperature profile and enhances desorption capacity.
• Thermal coupling via SOFC radiation alone leads to non-uniform heating, limiting desorption efficiency.
• The 3D validated model accurately predicts desorption dynamics, confirming the reliability of the simulation framework.
• Desorption performance is significantly improved when waste heat from the SOFC is effectively utilized, reducing reliance on external energy sources.
• The study demonstrates that thermal integration with SOFC can enhance both the efficiency and capacity of MgH₂ hydrogen storage systems.