Lightweight reactor design by additive manufacturing for preheating applications using metal hydrides

Thermal energy storage systems based on metal hydrides can be a solution for preheating fuel cells (FCs). They can provide thermal energy at temperatures below -20 degrees C during startup, while heat at 50 degrees C during operation is sufficient for regeneration. The challenge of such a system in mobile applications is the final weight specific thermal power. In this study, a reactor design based on additive manufacturing techniques for similar to 300 g of metal hydride is presented. Here, a reactor (passive) to hydride (active) mass ratio of 0.97 is realized, still reaching high weight specific thermal power of up to 2.1 kW/kgMH at -20 degrees C and 8 bar (LmNi(4.91)Sn(0.15)). Considering the example of preheating a FC from-20 degrees C in similar to 120 s, the performance of LaNi5 and LmNi(4.91)Sn(0.15) is studied. While LaNi5 requires higher regeneration temperatures than LmNi(4.91)Sn(0.15) (>40 degrees C compared to >20 degrees C), its performance is less sensitive to operative variations due to its nearly ideal thermodynamic characteristic. (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

Thermal energy storage systems based on metal hydrides can provide thermal energy for fuel cells, with the challenge of weight specific thermal power in mobile applications. A reactor design using additive manufacturing techniques achieved high weight specific thermal power, with performance comparison between different metal hydrides.