In this work, the reduction potential in soot particle number and mass when using Sustainable Aviation Fuel (SAF) with different mixture proportions (30%, 50% and 100% HEFA-SPK) is shown based on a measurement campaign carried out on a helicopter engine (Allison 250- C20B) in summer 2023. The gaseous and particulate matter emissions were analyzed at different load settings of the engine. The change of the load setting is linked to changes in gaseous and particulate matter (PM) emissions. For the gas phase the emission indices (EI’s) of CO and UHC are reduced at higher load settings due to higher combustion chamber efficiency, resulting from better fuel atomization, fuel-air mixing behaviour and higher flame temperatures. The difference in the gaseous EI’s between the fuel-SAF blends used are negligible for all regulated gaseous (CO, UHC, NOx) and volatile organic compounds (C2-C9) and were comparable to previous studies conducted with regular Jet A-1 (Rohkamp et. al. 2023). However, there is a clear change in the number, mass, and formation behaviour of the soot particles using different fuel-SAF blends. The non-volatile particulate matter (nvPM) number concentration was reduced for Ground-Idle (GI) by up to 80% using 100% SAF compared to regular Jet A-1 (see Table 1.). Due to the change of the particle diameter, the particle mass was reduced by up to 40%. Using (low aromatic) synthetic fuel shifts the mode (Figure 1.) of the particle number size distribution (PNSD) by 50% in diameter. For example: the geometric mean diameter (GMD) mode for Take-Off (TO) using 100% SAF is 30nm and using Jet A-1 is 60nm. This behaviour can be explained primarily due to the composition of the synthesized kerosene. For a detailed comparison of the soot particles the number concentration (CPC), size distribution (SMPS+DMS), mass (gravimetry) and appearance (SEM) were compared. The authors thank Munich Aerospace e. V. - Bavarian Research Alliance and the UniBw FORscience-project funding. In addition, this research [project LUKAS and MORE] is funded by dtec.bw – Digitalization and Technolgy Research Center of the Bundeswehr. Dtec.bw is funded by the European Union – NextGenerationEU. This research was also supported by the project ULTRHAS – ULtrafine particles from TRansportation – Health Assessment of Sources, a project funded under the EU’s Research and Innovation programme Horizon 2020, Grant Agreement No. 955390. We would also like to thank the company Neste, specifically J. Vilja and R. Sallinen, for providing the SAF.    «

In this work, the reduction potential in soot particle number and mass when using Sustainable Aviation Fuel (SAF) with different mixture proportions (30%, 50% and 100% HEFA-SPK) is shown based on a measurement campaign carried out on a helicopter engine (Allison 250- C20B) in summer 2023. The gaseous and particulate matter emissions were analyzed at different load settings of the engine. The change of the load setting is linked to changes in gaseous and particulate matter (PM) emissions. F...    »