Alternative Fuels for Aviation (Mobilise)

The specific energy of liquid fuels for example kerosene is 12 kWh/kg, which is approximately 80 times higher than that of lithium-ion batteries (0.15 kWh/kg). From this point of view, liquid fuels will be still important for future aviation. Future liquid fuels can be synthetically produced with sustainable energy sources by means of renewable electricity surpluses (power-to-liquid approach) in the vision of future mobility.  It is the main work for research alliance between the TU Braunschweig and the Leibniz Universität Hannover as part of the research program - MOBILISE - Fuels of the Future to achieve this vision.

In this context, the synthetically produced fuels should be designed for the desired functions as far as possible. Conventional fuels are used for diffusion-like combustion in today's aircraft engines.  Therefore, pollutant emissions like soot particles are formed in areas of inhomogeneous rich fuel-air mixtures. In areas of stoichiometric or slightly lean mixtures, NOx emissions are highly formed. Low-emission lean premixed combustion (LPP-Concepts) with no soot and very low NOx emissions is not applicable so far due to the risk of autoignition in the mixing area.

Therefore, the final goal is to develop new fuels or fuel mixtures, which can be used for premixed combustion without any risk of flashback and autoignition. According to the partnership, producing sustainable fuels are investigated in Braunschweig, and combustion characteristics of the fuels are investigated by conducting numerical simulations using detailed reaction kinetics in ITV. In addition, a model combustor will be designed for the investigation of ignition and flashback behavior in ITV. These investigations allow estimating the potential of the fuels for future aircraft engines.

This research project is funded by the Lower Saxony Ministry of Science and Culture. Furthermore, an excellence cluster "Sustainable and Energy Efficient Aviation" is proposed as a next step of the current project in order to expand the research activities and gain deeper knowledge to apply premixed combustion in future aircraft engines.