Effects of isopropanol-n-butanol-ethanol blends on combustion and emissions performance in a spark assisted compression ignition (SACI) engine

Abstract

To achieve carbon peaking and carbon neutrality goals, it is urgent to improve the thermal efficiency of engines and application of carbon-neutral fuels. The renewability and low emissions of isopropanol-n-butanol-ethanol (I-B-E) blends were receiving increasing attention, and spark-assisted compression ignition (SACI) was a high-efficiency combustion mode suitable for future engines. Therefore, this article designed 11 different I-B-E blends and investigated their differences in combustion and emissions performance under SACI combustion mode. It was found that regardless of the load, there was little difference in the auto-ignition timing of various I-B-E blends. Increasing the content of isopropanol and ethanol in I-B-E resulted in a decrease in the ratio of auto-ignition, COV_IMEP, COV_Pmax and COV_PRRmax. Regardless of the I-B-E composition, there was no significant relationship between COV_CA5-CI and COV_CACI-90. At light load, increasing the energy ratio of ethanol in I-B-E blends increased ITE by 2.11 % compared to n-butanol. After the load increased, regardless of the load, adjusting the composition of the I-B-E blends appropriately can achieve highest ITE and lowest ESFC. Increasing the energy ratio of ethanol and isopropanol in I-B-E blends was beneficial for reducing BSNOx and BSHC emissions. The BSCO emissions were not significantly related to the I-B-E components.