A generic physical model for a thermally integrated high-temperature PEM fuel cell and sodium alanate tank system Andreas G. Yiotis * , Michael E. Kainourgiakis, Georgia C. Charalambopoulou, Athanassios K. Stubos Environmental Research Laboratory, National Center for Scientific Research ‘Demokritos’, 15310 Athens, Greece article info Article history: Received 13 March 2015 Received in revised form 28 May 2015 Accepted 29 May 2015 Available online xxx Keywords: H 2 storage tanks Thermal coupling Sodium alanate High temperature PEM fuel cell Physical model abstract We study the thermal coupling potential between a Sodium Alanate tank and a High- Temperature PEM fuel cell using a heat transfer fluid to redirect a fraction of the thermal power produced during normal fuel cell operation towards the walls of the metal hydride tank in order to maintain hydrogen desorption. The remaining thermal power is then rejected to the environment by introducing an appropriately adjusted excess of air directly to the fuel cell cathode. Assuming a typical tubular geometry for both the metal hydride tank and the fuel cell, we propose a generic physical model that accounts for heat transfer in all the components of the integrated system (fuel cell, metal hydride tank and heating jacket), as well as H 2 desorption kinetics and flow in the tank. Based on this model we study the dynamics of the coupled storage/usage system in terms of H 2 pressure in the tank and temperatures in the tank and the fuel cell. Focus is primarily placed on the parameters that lead to steady-state operating conditions (i.e. the flow rate of air towards the fuel cell and the velocity of the heat transfer fluid in the heating jacket), with respect to the electrical power of the fuel cell. Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Among the main technological and economic challenges that have to be addressed to enable the widespread use of hydrogen-powered devices and vehicles is the need for com- bined improvements in both fuel cell (FC) and H 2 storage technologies to bring closer to reality the development of cost- effective, integrated storage and usage systems. The materials-based hydrogen storage tanks that have been developed so far are mainly based on metal hydrides (MHs) due to their increased gravimetric/volumetric capacity, as well as their stability, in some cases, over longterm cycling [1,2]. Hydrogen storage in MHs is an exothermic process that produces significant excess heat (in the range of 20e80 kJ/mol H 2 for common materials), as atomic hydrogen is bound chemically into the bulk of the material. Unless this produced excess heat is removed, it leads to increasing tank tempera- tures that eventually satisfy the activation energy barrier for desorption. As such, the material can no longer absorb more * Corresponding author. Tel.: þ30 210 6503408; fax: þ30 210 6525004. E-mail address: yiotis@ipta.demokritos.gr (A.G. Yiotis). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2015) 1 e11 http://dx.doi.org/10.1016/j.ijhydene.2015.05.186 0360-3199/Copyright © 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Yiotis AG, et al., A generic physical model for a thermally integrated high-temperature PEM fuel cell and sodium alanate tank system, International Journal of Hydrogen Energy (2015), http://dx.doi.org/10.1016/ j.ijhydene.2015.05.186