Probing intermediate temperature heat release in autoignition of C3-C4 iso- alcohol/gasoline blends

摘要

This work reports an experimental and modeling study on the blending effects of C3–C4 iso- alcohols,namely iso- propanol and iso- butanol, on the characteristics of intermediate temperature heat release(ITHR) for a research-grade gasoline (FACE-F) in a rapid compression machine operating at diluted/stoichiometric fuel loading, compressed pressure of 43 bar, and compressed temperatures from 700to 970 K. Changes in ITHR behavior are characterized through ITHR extent and evolution at 0 to 30 vol%iso- alcohol blending levels. Experimental observations reveal the strong promoting and decelerating effectson ITHR extent and evolution, respectively, within the low-temperature regime for both iso- alcohols,with stronger effects seen for iso- propanol; within the intermediate-temperature regime, the influence ofboth iso- alcohols diminishes greatly. Comprehensive chemical kinetic modeling is undertaken using a recentlydeveloped gasoline surrogate/alcohol model in conjunction with a five-component gasoline surrogate(FGF-LLNL), with good agreement obtained with the experiments for all the blends. Sensitivity, rateof production and flux analyses highlight the importance of chemical kinetic interactions via both fuelspecificand non-fuel-specific reactions. Disabling all the chemical kinetic interactions between iso- alcoholand FGF-LLNL in carbonated/non - fuel-specific species leads to somewhat extended ITHR duration andreduced ignition reactivity. Direct comparison between FGF-LLNL/ iso- propanol and FGF-LLNL/ iso- butanolblends is also made, where iso- propanol and iso- butanol are found to influence ITHR characteristics viasignificantly different chemical kinetic interactions.