Periodic Reporting for period 1 - MINIMAL (Minimum environmental impact ultra-efficient cores for aircraft propulsion.)
Reporting period: 2022-09-01 to 2024-02-29
MINIMAL aims at providing aircraft propulsion technology that can support the transition to climate neutrality by year 2050. This is achieved by providing technology that can attacks the major sources of CO2 and non-CO2 emissions in aeroengines, with the potential to (in relation to best year 2020 technology):
• reduce emissions from contrail cirrus by 80%,
• reduce net-NOx by 52%,
• and improve efficiency by 36% (leading to 80% CO2 reduction considering the use of MINIMAL Sustainable Aviation Fuel (SAF) and LH2 concepts, or 36% using conventional jet fuel
New propulsion systems fuelled by hydrogen or sustainable aviation fuel (SAF), and using composite cycle engine (CCE) technology, will offer unparalleled thermal efficiency and performance flexibility for climate-friendly operations. The end goal is to identify the engine design options giving minimal climate impact. Three competing engine concepts will be investigated:
• Turbofan with an intercooled crankshaft topping core.
• Turbofan with an intercooled opposed free piston topping core.
• Turbofan with an intercooled dual free piston topping core.
MINIMAL also targets the experimental (TRL 3) proof of concept of cutting-edge technologies enabled by liquid hydrogen fuel:
• opposed-piston low-NOx hydrogen combustion.
• heat-management systems that exploit the cooling potential of hydrogen.
• reduce emissions from contrail cirrus by 80%,
• reduce net-NOx by 52%,
• and improve efficiency by 36% (leading to 80% CO2 reduction considering the use of MINIMAL Sustainable Aviation Fuel (SAF) and LH2 concepts, or 36% using conventional jet fuel
New propulsion systems fuelled by hydrogen or sustainable aviation fuel (SAF), and using composite cycle engine (CCE) technology, will offer unparalleled thermal efficiency and performance flexibility for climate-friendly operations. The end goal is to identify the engine design options giving minimal climate impact. Three competing engine concepts will be investigated:
• Turbofan with an intercooled crankshaft topping core.
• Turbofan with an intercooled opposed free piston topping core.
• Turbofan with an intercooled dual free piston topping core.
MINIMAL also targets the experimental (TRL 3) proof of concept of cutting-edge technologies enabled by liquid hydrogen fuel:
• opposed-piston low-NOx hydrogen combustion.
• heat-management systems that exploit the cooling potential of hydrogen.
The first stage of the project during the initial 18 months was dedicated to ground preparation work for future research activities. The work started with the definition of the technological assumptions for year 2035, followed by the definition of the reference 2020 and baseline 2035 TRL6 engines. The work towards the definition of baseline aviation technology is progressing well, and the exchange of engine performance data already started to support the airframe design activities. Regarding the development of supporting models to estimate the impact of baseline and MINIMAL’s technology, the development and implementation of an aircraft fleet model allowing to estimate the global emission impact up to year 2050, under different techno-economic scenarios is now completed. At the same time, emission inventories were defined for year 2019 and are reported, together with the initial 2050 emission projections.
The maturation of intercooled CCE technologies to TRL 2 is following the predefined plan, without any major deviations. Models have been created at the component and system level, to predict the performance of all three topping cycles (crankshaft-based, free-dual, opposed), including hydrogen combustion models, and heat-transfer performance. Also, the thermal system requirements and constraints were defined during a dedicated project workshop in October 2023.
The progress towards the maturation of key concepts to TRL3 is also following the anticipated path. The down-selection of the novel hydrogen intercooler design is following the established plan and several TRL2 activities are ongoing, leading to the initial preliminary system design. Several piston cooling strategies are also currently being evaluated at TRL2. This work is supported by the creation of new or tailored heat-exchanger design tools. Regarding the low-NOx combustion rig, the requirements were defined in a collaboration between WP2 and WP4, and the rig design activities have already started. A roadmap for the rig commission was initiated towards the kick-off of experimental activities in 2025.
The maturation of intercooled CCE technologies to TRL 2 is following the predefined plan, without any major deviations. Models have been created at the component and system level, to predict the performance of all three topping cycles (crankshaft-based, free-dual, opposed), including hydrogen combustion models, and heat-transfer performance. Also, the thermal system requirements and constraints were defined during a dedicated project workshop in October 2023.
The progress towards the maturation of key concepts to TRL3 is also following the anticipated path. The down-selection of the novel hydrogen intercooler design is following the established plan and several TRL2 activities are ongoing, leading to the initial preliminary system design. Several piston cooling strategies are also currently being evaluated at TRL2. This work is supported by the creation of new or tailored heat-exchanger design tools. Regarding the low-NOx combustion rig, the requirements were defined in a collaboration between WP2 and WP4, and the rig design activities have already started. A roadmap for the rig commission was initiated towards the kick-off of experimental activities in 2025.
Most of the work done so far was about laying down the foundations for the subsequent address of key research questions:
• “How can MINIMAL’s CCE technology contribute to a reduction in climate impact from aviation?”
• “Will that reduction be sufficient to address the climate goals set by the Paris Agreement?”
Hence the work so far was focused on the development of new or tailored existing models to predict the system performance from a component level to an entire fleet of aircraft. Therefore, it is too soon to claim any major scientific or technological achievements in MINIMAL. Still, already in this early stage of the project we see a contribution to the state of the art with MINIMAL’s first journal publication on the effects of engine design parameters on climate impact, the paper feature the cover page of Aerospace (https://www.mdpi.com/2226-4310/10/12/1004(opens in new window)). Additionally, MINIMAL contributed with 10 conference presentations. MINIMAL also contributed to the recruitment of PhD students and young researchers, and ensure their visibility withing European aviation stakeholders, through their participation in general assemblies, meetings, workshops and conferences.
• “How can MINIMAL’s CCE technology contribute to a reduction in climate impact from aviation?”
• “Will that reduction be sufficient to address the climate goals set by the Paris Agreement?”
Hence the work so far was focused on the development of new or tailored existing models to predict the system performance from a component level to an entire fleet of aircraft. Therefore, it is too soon to claim any major scientific or technological achievements in MINIMAL. Still, already in this early stage of the project we see a contribution to the state of the art with MINIMAL’s first journal publication on the effects of engine design parameters on climate impact, the paper feature the cover page of Aerospace (https://www.mdpi.com/2226-4310/10/12/1004(opens in new window)). Additionally, MINIMAL contributed with 10 conference presentations. MINIMAL also contributed to the recruitment of PhD students and young researchers, and ensure their visibility withing European aviation stakeholders, through their participation in general assemblies, meetings, workshops and conferences.