Abstract Aviation remains a major contributor to air pollutant emissions. While full decarbonization through electrification or carbon-free fuels is not feasible in the near term, Sustainable Aviation Fuels (SAF) offer a promising interim alternative. This study examines the emission behavior of a synthetic paraffinic kerosene (FT-SPK), produced via the Fischer-Tropsch process, and compares it to both conventional Jet A-1 and previously tested HEFA-SPK. Experiments were conducted on an Allison 250-C20B turboshaft engine using Jet A-1, a 50% FT-SPK and HEFA-SPK blend, and 100% FT-SPK and HEFA-SPK. Engine power settings were selected based on the ICAO LTO-cycle. Non-volatile particulate matter (nvPM) was analyzed with a condensation particle counter (CPC) and a scanning mobility particle sizer (SMPS), while gaseous emissions (CO2, NOx, CO, UHC) were measured using a FTIR/O2/FID combi-system. A resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI ToF-MS) provided insight into polycyclic aromatic hydrocarbons (PAH) in the exhaust. Both 100% FT-SPK and HEFA-SPK demonstrated similarly strong reductions in nvPM at low power settings compared to conventional Jet A-1, though differences became apparent at higher power settings. Further, the 50% FT-SPK blend consistently showed greater nvPM reductions than the 50% HEFA-SPK blend across all power settings. Compared to HEFA-SPK, FT-SPK showed similar gaseous emission behavior at high power settings but indicated more complete combustion at low power, with higher CO2 and lower CO and UHC emissions.
Rabl et al. (Fri,) studied this question.