Modeling Methodology for PEM Fuel Cells as Auxiliary Power Units in Aircraft Applications

Proton Exchange Membrane Fuel Cells (PEMFCs) have been receiving considerable coverage by both academic and industrial sectors as a favorable means to reduce the environmental footprint of air travel by decreasing reliance on fossil fuels. This paper presents a methodology aimed at identifying opportunities for integrating fuel cells into aircraft as replacements for traditional Auxiliary Power Units (APUs) with the objective of minimizing the aircraft’s overall environmental footprint. To maximize the environmental benefits and support the transition toward the More Electric Aircraft concept, the conventional APU mission profile is redefined to eliminate customer bleed air—traditionally used for the Environmental Control System (ECS)—and engine shaft power extraction for electric generators, thereby reducing Jet-A fuel consumption in the main engines. As a result, the proposed fuel cell system is designed to supply both electrical power and compressed air to the aircraft subsystems. To evaluate the feasibility of this approach at the aircraft level, a comprehensive PEMFC system model is developed within the Numerical Propulsion System Simulation (NPSS) environment. This model enables a detailed sizing and synthesis process at the aircraft level, which will be explored in future studies to quantify the benefits and trade-offs associated with the proposed PEMFC system and to identify associated optimal design configurations.