Refuelling Innovations
INNOVATION
ALRIGH2T will introduce cutting-edge ideas and technologies for hydrogen-based aviation, pushing the boundaries of current advancements in the field. The project aims to exceed the current state of the art by making significant contributions to the use of hydrogen in aviation, which is recognized as a promising decarbonization technology for the industry.
Concepts & technologies
SUPPLY & MANAGEMENT
DIRECT Refuelling of LH2
Two methods are currently used for refuelling LH2: a reciprocating pump and pressurization by partial LH2 evaporation. The first method has a flow rate limitation of 200 kg/h, while the second method is inefficient due to the need to evaporate a significant amount of LH2 for pressurization, reducing available fuel.
Tank swapping refuelling technology
There is a proposal for a modular capsule technology for safe hydrogen storage, facilitating direct loading onto aircraft, thus creating a capital-light distribution system. The use of hydrogen tanks for hydrogen-powered aircrafts has been demonstrated as well as tank swap applications in the automotive sector.
Safety barrier performance requirements
Dangers linked with LH2 direct refuelling infrastructure, tank swapping and LH2 handling, include hydrogen release and containment loss, posing risks of freezing, frostbites, fire, and explosions. Current systems require large safety zones to mitigate these risks, limiting simultaneous activities at airports. Safety systems and barriers aim to reduce the consequences of hydrogen spills.
COMPONENTS FOR LH2-POWERED AVIATION
Tank for LH2 storage and instrumentation
Large LH2 tanks have long been employed in industrial contexts. An automotive company introduced smaller containers with a capacity of up to 8 kg, utilizing a vent-line system to release gas and reduce pressure during refuelling.
Direct refuelling process & filling station
The refuelling of large amounts of LH2 from LH2 trailers to the internal aircraft LH2 tank, in a time compatible with normal airport operations, will require an accurate control of the whole process. Filling involves a rapid pressure increase, and inner fuel level sensors can’t accurately measure swap levels.
VIRTUAL MODELS & TOOLS
Digital twin & simulation of the refuelling process
The Digital Twin (DT) is a digital model that replicates physical processes for real-time control and management. It requires accurate representation of the system through tests and simulations, constructing reduced-order models with key physical mechanisms. Existing DTs focus on automotive applications with non-cryogenic hydrogen, lacking global validity. LH2 applications face unique challenges such as high heat transfer during initial filling and nonlinear evaporation rates, necessitating tailor-made tank models.
Virtual-Reality training of refuelling operator
The expertise gained in the development of IT technologies today allows to offer advanced solutions in Augmented Reality and Virtual Reality (VR) for comprehensive training services.
Modelling & application to LH2 safety distance
Existing hydrogen safety models mainly address gaseous releases, with limited focus on cryogenic hydrogen. While some models can be adapted, they often rely on simplifications from tests on other liquefied gases. Key challenges in hydrogen dispersion modelling include understanding the cloud’s behaviour based on density-wind equilibrium. Recent large-scale tests offer opportunities to validate existing models and develop new approaches
REFUELLING PROCESS
Specifications for H2 system integration
Aviation kerosene is a liquid at ambient temperature and pressure, easily stored within wing and fuselage tanks, but hydrogen is a gas at ambient temperature and pressure and needs to be liquefied at around -250°C to increase its energy density. The need for lightweight, well-insulated cryogenic tanks poses challenges for their design and distribution system.
Refuelling technology evaluation
There is no analysis comparing refuelling technologies across various metrics such as refuelling time, safety, economics, and scalability to different aircraft and airport sizes. Tank swapping, an innovative yet untested technology, contributes to this gap.
Airframe integrator-informed refuelling process
Safe refuelling operations require strict adherence to procedures and safety precautions by refuelling operators and other ground personnel. The main threat is fire, so three key aspects are considered: bonding, grounding, and refuelling safety zones.
Procedures for safe ground movements
Safe refuelling demands strict adherence to procedures and safety precautions tailored to the specific fuel type, particularly with the novelty of hydrogen fuelling. These procedures must adhere to aeronautical rules, undergo validation by authorities, and be incorporated into the airport operator’s manual.
DEMOSTRATION
Ground use of hydrogen
Airport emissions originate not only from aircraft operations but also from ground vehicles used in handling operations. Hydrogen fuel cells, particularly in proton exchange membrane fuel cells (PEMFCs), offer a promising solution to reduce emissions. PEMFCs, widely used in automotive sectors, are gaining traction due to hydrogen’s clean nature and its ability to address limitations of battery electric vehicles like operational time and recharging.
LH2 refuelling demonstrations in 2 airports
Hydrogen and fuel cells in aviation, already demonstrated, are crucial for decarbonizing air transport. Airport operators must anticipate challenges and impacts on operations and design as hydrogen adoption grows.