Effects on the design of aeronautical fuel cell systems by inclusion of reliability requirements

Abstract

The change towards carbon neutrality in air traffic involves a huge reduction of greenhouse gas emissions. This goal is beyond reach by the step wise improvement of conventional technologies. Hence, at present a solution which gains much of attraction are electric motors and electric aircraft systems in combination with fuel cells which can be run by green hydrogen. For a holistic comparison of various concepts the consideration of reliability aspects is required even at an early stage of design. In the scope of this work methods from reliability and safety engineering will be introduced and set in context of aeronautical fuel cell systems. On that basis the consequences arising by the requirement of redundancy are investigated on a system level approach. For this purpose, a model of an aeronautical fuel cell system will be set up in order to simulate a generic flight envelope at stationary points. The fuel cell system is chosen to be central-monolithic and its components are sized for the propulsion of a regional aircraft. With the aid of the system simulation, various failure scenarios are investigated from which mitigation strategies can be derived. Finally, the baseline design will be improved in terms of redundancy in order to last in a generic failure scenario. A comparison between the baseline and improved design shows that the additional redundancy comes with the cost of 4.6% weight increase and a 2.5% drop in cruise efficiency.