Development of an additively manufactured lightweight heat exchanger for cooling waste heat streams in fuel cell-powered aircraft

Hydrogen represents a promising alternative fuel for the realization of climate-neutral mobility solutions in the aviation sector. In the field of small and regional aircraft, fuel cell-based propulsion systems are a preferred solution. In contrast to the direct combustion of hydrogen in gas turbines, these systems lack the cooling airflow associated with high mass flow rates of air. Current fuel cell systems achieve an overall efficiency of approximately 50%, meaning that nearly the same amount of energy as the required electrical propulsion power must be dissipated as waste heat. This necessitates the use of efficient cooling systems employing heat exchangers.

Aviation faces the challenge of utilizing heat exchangers that are as compact and weight-efficient as possible. Additive manufacturing technologies offer new opportunities in this regard. Compared to conventional manufacturing methods, these technologies provide significantly greater design freedom, reduce material requirements, and enable a highly integrated design tailored to the structure of the aircraft.
Motivated by these advantages, the joint research project focuses on the development of additively manufactured heat exchangers for use in fuel cell-based aircraft propulsion systems, using the example of an electric light aircraft.

Project Objectives:

• Selection and characterization of materials with respect to specific strength and suitability for additive manufacturing

• Development of a methodology for the thermodynamic design of additively manufactured lightweight heat exchangers

• Development of a methodology for the structural design and optimization of additively manufactured lightweight heat exchangers

• Development of an experimental testing protocol and its execution, focusing on thermomechanical behavior, vibration characteristics, and residual stresses using test specimens

• Experimental testing of thermal performance to determine thermodynamic parameters using test specimens

• Development of a demonstrator based on representative load cases derived from previous findings

• Experimental testing of the demonstrator regarding structural and thermodynamic performance, including comparison with simulation data

• Visualization and documentation of the design methodology for lightweight heat exchangers with a focus on mobility applications