(509bc) Blending Rule for Predicting the Sooting Tendencies of Gasoline Mixtures from the Individual Components

With the growing importance of climate change, soot has been receiving increasing attention since it is the second largest source of global warming [1]. A sooting tendency can be used to quantify the extent of soot formation in a combustion device for a given fuel molecule. However real fuels are complex mixtures of multiple components. In this work, we are using both experimental and computational methods to investigate how the sooting tendency of a blended fuel mixture is related to the sooting tendencies of the individual components. A test matrix was formulated that includes sixteen mixtures of six components that are representative of the main categories of hydrocarbons in gasoline (n-heptane for alkanes, isooctane for isoalkanes, methylcyclohexane for naphthenes, toluene for aromatics, 1-hexene for olefins, and ethanol for oxygenates). The mixtures contain up to five components. Sooting tendency was characterized by yield sooting index (YSI), which is the soot yield when a methane/air flame is doped with 1000 ppm of the test fuel. The YSI of each mixture has been measured experimentally and determined computationally from detailed flame simulations using procedures in [2, 3]. Preliminary results show that the blending behavior is linear, i.e., YSI_mix = Σ_j X_j YSI_j, where YSI_mix is the sooting tendency of the mixture, X_j is the mole fraction of component j, YSI_j is the sooting tendency of component j as a pure compound, and the sum is over all the components j in the mixture.

[1] TC Bond et al., J Geophys Res-Atmos. 2013, 118:5380-552.

[2] CS McEnally et al., Proc. Combust. Inst. 2019, 37:961-8.

[3] H Kwon et al., Fuel 2020, 276:118059.