Passive Anode Recirculation in PEM Fuel Cell Systems: Enhancing Efficiency and Performance

Authors

G. Singer, M. Rabensteiner, R. Pinsker, T. Hafner, M. Aggarwal, P. Pertl, HyCentA Research GmbH, Graz; A. Trattner, Graz University of Technology / HyCentA Research GmbH, Graz:

Year

2024

Print Info

Production/Publication ÖVK

Summary

Proton exchange membrane (PEM) fuel cells are increasingly seen as a viable option for clean energy in mobility, thanks to their high efficiency and low greenhouse gas emissions. A major challenge in improving PEM fuel cell systems is to increase the efficiency of the anode recirculation. Using an ejector, which acts as a jet-pump in the anode path, is a more effective and sustainable choice than an electrically powered blower. Ejectors are more durable, energy-efficient, and maintenance-free. However, designing an ejector that ensures sufficient hydrogen recirculation across the entire operating range in a PEM fuel cell stack is complex. This study introduces an innovative two-step needle ejector that efficiently manages hydrogen supply and recirculation for a stack load range of 6 % to 100 %. The design and optimization of this ejector involved a comprehensive approach, incorporating basic thermodynamics, computational fluid dynamics, design of experiments optimization, prototyping, and experimental testing. Moreover, the next generation ejector utilizes an advanced additive manufacturing process – HP Multi Jet Fusion (MJF) with polyamide 12. This choice reduces the mass of the ejector by over 90 % and that of the complete ejector recirculation system by over 70 %, which is particularly advantageous in automotive applications. In summary, this research advances the industrialization of PEM fuel cell technology by setting a new standard in ejector performance and mass reduction.

ISBN

978-3-9504969-3-2

DOI

https://doi.org/10.62626/ob5b-45kd