Optimal Design of a Hydrogen-powered Fuel Cell System for Aircraft Applications

Recently, hydrogen and fuel cells have gained interest as an emerging technology to mitigate the effects of climate change caused by the aviation sector. The aim of this work is to evaluate the applicability of this technology to an existing regional aircraft in order to assess its electrification, with the aim of reducing greenhouse gas emissions and achieving sustainability goals. The design of a proton-exchange membrane fuel cell system (PEMFC) with the inclusion of liquid hydrogen storage is carried out. Specifically, a general mathematical model is developed, which involves multiple scales, ranging from individual cells to aircraft scale. First, the fuel cell electrochemical model is developed and validated against published polarization curves. Then, different sizing approaches are used to compute the overall weight of the hydrogen-based propulsion system, in order to optimize the system and minimize its weight. Crucially, this work underscores that the feasibility of hydrogenbased fuel cell systems relies not only on hydrogen storage but especially on the electrochemical cell performance, which influences the size of the balance of plant and especially its thermal management section. In particular, the strategic significance of working with fuel cells at partial loads is demonstrated. This entails achieving an optimal balance between the stacks oversizing and the weights of both hydrogen storage and balance of plant, thereby minimizing the overall weight of the system. It is thus shown that an integrated approach is imperative to guide progress towards efficient and implementable hydrogen technology in regional aviation. Furthermore, a high-performance PEMFC is analyzed, resulting in an overall weight reduction up to nearly 10% compared to the baseline case study. In this way, it is demonstrated as technological advancements in PEMFCs can offer further prospects for improving system efficiency.