(Digital Presentation) Heat Transfer Enhancement in Room-Temperature Metal Hydride Storage Systems

Among the existing methods of short- and long-term storage of renewable energy, reversible metal hydrides (MH) are considered safe and volume efficient. They provide efficient hydrogen storage capacity for various applications, including Low Temperature PEM Fuel Cells (LT PEMFCs) [1]. The heat transfer in the MH reactor has a substantial influence on the efficiency of the storage process. In order to achieve the established goals for tank filling times, enhanced heat transfer techniques will be essential [2]. Therefore, this work investigates technical solutions for thermal conductivity enhancement in MH storage systems. Different tank designs are assessed in terms of their applicability and the effect of different solid matrices in the storage system on the internal heat transfer is studied. With the help of thermal imaging, the impact of the geometry of the solid matrices on the uniformity of gas distribution along the MH bed is analysed. The MH tanks are operated with room temperature (RT) metal hydrides that achieve a hydrogen storage capacity of up to 105 kgH2 m−3 in a wide range of temperatures (from 50 to -40°C). The tests are carried out within a limited pressure range of 1 to 0.1 MPa to reduce the reliance on additional H2 compressors when used in stationary applications. [1] M. V. Lototskyy et al., „Metal hydride systems for hydrogen storage and supply for stationary and automotive low temperature PEM fuel cell power modules“, Int. J. Hydrog. Energy, Bd. 40, Nr. 35, S. 11491–11497, Sep. 2015. [2] K. C. Smith, Y. Zheng, T. S. Fisher, T. L. Pourpoint, und I. Mudawar, „Heat Transfer in High-Pressure Metal Hydride Systems“, J. Enhanc. Heat Transf., Bd. 16, Nr. 2, S. 189–203, 2009.