Session: 18-01 Advanced Manufacturing and Design I

Paper Number: 125888

125888 - Challenges in the Production of Fuel Cells for Aviation 

The influence of increasing resource scarcity and climate change has a significant impact on aviation. Therefore, the European Commission has set ambitious goals with a 75 % reduction in CO₂ and a 90 % reduction in NO_x as part of the Flightpath 2050 vision. Achieving these goals requires the use of disruptive technologies in aviation, especially in propulsion. In addition to the use of Sustainable Aviation Fuel (SAF), the use of hydrogen is a promising alternative. There is the possibility of the direct use of liquid hydrogen in gas turbines as well as the use of fuel cells. In the last-mentioned application, the fuel cell acts as an energy converter and powers the primary electric drives, offering the potential to fly emission-free, especially for short- and medium-range flights.

However, successful integration of the fuel cell into the aircraft's powertrain requires a significantly increased gravimetric power density (> 6 kW/kg) compared to the status quo. Furthermore, the fuel cell and the entire manufacturing process chain must fulfill the stringent safety requirements of aviation. Therefore, the bipolar plate and, respectively, its production process are key elements for the fuel cell. The process chain to produce bipolar plates is complex due to numerous technologies and process steps, the most relevant are forming, cutting and welding with associated cleaning, as well as testing and integration into the fuel cell stack.

In the context of aviation fuel cell applications, an understanding of the cause-and-effect relationships in the forming process is essential. This paper describes how a basis for an aviation-compliant quality assurance of the forming process can be established with a combination of comprehensive material characterization, numerical forming simulation and digitization options for process monitoring. After the forming process, there are various possible process sequences for cutting, welding and coating bipolar plates. The quality requirements, such as geometric positioning in the micrometer range needed for aviation, pose challenges for both the individual process and the process chain. This paper outlines these challenges, along with ways to address them in an interlinked production process. In the cutting and welding process, for example, thermal damage to the material is a possible source of damage. Possible test strategies to detect this damage and integrate it into the process chain are also presented. The materials used to achieve the required gravimetric energy density, such as titanium or aluminum, or an upstream or downstream coating, are also considered in the individual process. Finally, the paper addresses the challenges of integrating the bipolar plates into a fuel cell stack. Especially in view of the high quality and safety requirements of the aviation industry, robust assembly processes have to be developed for the large number of components of a fuel cell stack in the form of several hundred bipolar plates and other stack components.

Presenting Author: Rainer Horstkotte Fraunhofer Institute for Production Technology IPT

Presenting Author Biography: Since 2018 research fellow at Fraunhofer IPT

Authors:

Patrick Sperling Fraunhofer Institute for Production Technology IPT
Rainer Horstkotte Fraunhofer Institute for Production Technology IPT
Jan Sommer Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
Sascha Gierlings Fraunhofer Institute for Production Technology IPT
Henning Janssen Fraunhofer Institute for Production Technology IPT
Tim Herrig Laboratory for Machine Tools and Production Engineering (WZL)
Thomas Bergs Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
Christian Brecher Fraunhofer Institute for Production Technology IPT