Investigation into ethanol effects on combustion and particle number emissions in a spark-ignition to compression-ignition (SICI) engine

Spark assistance along with oxygenated components addition is a promising method to achieve stable compression ignition, high thermal efficiency and low particle emission. To this end, ethanol blended non-oxygenated gasoline was fueled an engine working spark-ignition compression-ignition (SICI) mode under air dilution exhaust-diluted conditions. The effects of on performance including combustion characteristics, fuel economy, number (PN) emissions, were studied in two categories: changing research octane (RON) by varying content maintaining RON type. results showed that splash blending suppressed knock tendency, the intensity could be lowered up 65–75% increasing content. However, when same RON, ethanol-gasoline blend exhibited higher than pure due synergistic between aromatics auto-ignition. Compared spark ignition high-RON gasolines, using blends SICI reduce minimum consumption rate 25 g/(kW·h). characterize high-efficiency cycles SICI, dimensionless parameters proposed considering ratios heat release amount duration flame propagation stage auto-ignition stage. good exponential correlation. As for basically PN emissions except cases significant increase nucleation particles, such as those stoichiometric condition poor quality heavily total reduction mainly decrease accumulation during rather Blending into will directly unburned hydrocarbons nitrogen oxides propensity or moderately lean conditions according temperature-pressure trajectory. Therefore, dedicated system ratio lean-boosted mixture required enhance ethanol's reactivity better economy emission diluted combustion.