Rapid Assessment of Jet Engine-Like Soot from Jet-A1 and Sustainable Aviation Fuels Made by a Spray Flame

Jason Scott, TIMOTHY SIPKENS, Rym Mehri, Gregory Smallwood, Mohammad Reza Kholghy, National Research Council Canada

     Abstract Number: 440
     Working Group: Combustion

Abstract
Black carbon, or soot, is one of the highest contributors to global warming. Soot is classified as a non-volatile particulate matter (nvPM), and the International Civil Aviation Organization (ICAO) is continually evolving their restrictions for jet engine emissions to combat the effects of harmful nvPM on the environment. Sustainable aviation fuels (SAFs) offer advantages to reduce soot emissions and overall environmental impact but require extensive testing and evaluation before wider adoption. Typical measurements of soot produced by aviation fuels require full-sized jet engines and large volumes of fuel, which can be prohibitively expensive. This study investigates flame spray pyrolysis (FSP) as a simple bench-top tool for comparison of soot emissions from different liquid jet fuels. A sampling assembly is designed for soot collection and analysis. Morphological analysis follows from TEM image analysis and combined mobility (differential mobility analyzer) and mass (centrifugal particle mass analyzer) classification. Morphologies are compared to previous measurements from aircraft turbines. Soot agglomerate size distributions and elemental to total carbon ratios (EC/TC) are measured for three liquid fuels and flame conditions with Reynolds numbers and burner equivalence ratios ranging from 6100 to 9100 and 7 to 13, respectively. Day-to-day variations in the dilution ratio resulted in up to 20% variability in the measured total agglomerate number density and mobility diameter. Geometric mean primary particle and mobility diameter values are below 21 and 113 nm, respectively, in excellent agreement with those emitted from jet engines and earlier works using FSP. EC/TC remains > 0.75 for most flame conditions and fuels and increases with burner equivalence ratio, but values as low as 0.63 are measured from SAFs.