Emissions from the aviation industry have increased significantly over the decades and may continue to pose an environmental threat. Accordingly, efforts are being made to replace conventional aviation fuels with more sustainable alternatives that can both reduce net CO2 emissions as well as reduce other pollutants (i.e., particulates). Conventional jet fuels include aromatic species, which have high sooting tendency. Therefore, to reduce particulate emissions, the fuel aromatics content must be reduced. Cycloalkanes have potential for replacing aromatics content in jet fuel but, compared to other broad classes of chemical species that make up conventional and alternative jet fuel, there is limited information available on the ASTM D1322 standard smoke points of many cycloalkanes. The smoke points of some unsubstituted, mono-alkyl substituted, and oxygenated cycloalkanes were determined in this study. Smoke point values obtained for alkylated cycloalkanes show that initial alkylation of cycloalkane ring increases sooting tendency, but further increase in n-alkyl chain length appears not to have a significant effect on the smoke points of alkylated cycloalkanes. Considering the effect of ring carbon number of cycloalkanes, a non-monotonic trend is observed for smoke point of cycloalkanes. This trend is different from the non-monotonic trend observed previously for derived cetane number (DCN) of these fuels. This interesting behavior further confirms the thermo-chemical "uniqueness" of cycloalkane fuels and should be investigated further.
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