C6.3 - DEFCA: Design-space evaluation of the air-, heat- and power-management of fuel cells for aviation

Motivation

Current research is focusing on hydrogen-based proton exchange membrane fuel cells (PEMFC) as a promising approach to reduce the climate impact of aviation. Given that aircraft operate within a wide range of environmental conditions at altitudes of up to 12 km, a key factor for the successful deployment of this technology is a robust air management system, capable of consistently delivering compressed and conditioned ambient air to the PEMFC stack throughout the entire flight envelope. The air management system has a significant impact on fuel cell efficiency and operating range, and thus on fuel consumption, waste heat and the total weight of the propulsion system.

The main focus of the project C6.3 "Design-space evaluation of the air-, heat- and power management of fuel cells for aviation" (DEFCA) is therefore the identification and optimisation of suitable system components and architectures for the air management system, which includes compressors and turbines with an additional electric drive, as well as heat exchangers and humidifiers. Within the scope of the project, these components are designed and then analysed in on- and off-design conditions in order to enable precise predictions of the performance and the expected operating range.

Objectives

The objective of the project DEFCA is to find the most promising combination of all air management components of a fuel cell-powered medium range aircraft in on- and off-design operating points. Based on design studies, suitable air supply architectures are analysed and constraints limiting the operating range are identified. Particular attention will be paid to the compressor and turbine, as these have a strong influence on system performance. These turbomachinery components are designed and general design rules for the cathode air management system are derived. In order to cover the entire flight envelope, additional operating states beyond the typical design parameters are included in the off-design performance analysis and optimisation. The following research questions will be investigated:

• Which system components limit the available design space at which specific critical operating points?
• Which system architectures and operating strategies provide the optimal performance under the given constraints?
• What are the most suitable compressor and turbine designs and what design improvements would provide the greatest system-level benefits?
• What are interdependencies between the aircraft design and the air, heat and power management of the fuel cell?

Methods

• Development of an on-design simulation tool for the investigation of the feasible operating range and the identification of feasible design points for the cathode air supply system
• System architecture studies for the cathode air supply system
• Development of an off-design simulation tool for performance analysis and optimisation
• Preliminary design of turbo components such as compressors and turbines (Multall) and selection of suitable topologies of the turbo components (radial, diagonal, or axial)
• 3D numerical flow simulation and optimisation