The challenges with electrification in the automotive industry have led to rethinking the decisions to ban internal combustion engines. Nonetheless, decarbonization of transportation remains a regulatory priority in many countries, irrespective of the energy source for automotive powertrains. Renewable oxygenated fuel components can help with the rapid decarbonization of gasoline fuels in the current fleet. Ethanol is one of the primary renewable components typically used for blending in gasoline primarily at 10% v/v but up to 20% v/v substitution which corresponds to 3.7 to 8.0% oxygen by mass. However, a range of oxygenates could be used instead of ethanol. This study aimed to determine if the engine could discriminate between different oxygenates in gasoline fuels blended at the same octane (RON) and oxygen levels.
Oxygenates such as methyl-tert-butyl-ether (MTBE) and ethyl-tert-butyl-ether (ETBE) were considered in this study. Blends were made using a combination of n-heptane, iso-octane, toluene, and oxygenated components. Seven blends with a nominal RON of 98 +/-2 were evaluated in a single-cylinder engine. Four E10 equivalent and three E20 equivalent fuel blends were studied. The engine was operated at a range of test conditions from throttled, low-load points to boosted, high-load points that required knock retard. The results indicated that all blends had minimal differences in engine performance in terms of knocking behavior, spark timing, burn duration, fuel flow, and injection duration which could all be compensated by the engine control unit (ECU). Particulate matter emissions (AVL micro soot sensor, PN10, PN23) were also evaluated at the test conditions. While the fuels had lower PM-generating components compared to commercial fuels, we could demonstrate that the PM emissions largely correlated with the particulate matter index (PMI) (or the toluene content) of the fuels.