Impact of Fuel Premixing Ratio and Injection Timing on Reactivity Controlled Compression Ignition Engine

Abstract

Stringent emission mandates and harmful effect of engine emissions on human health as well as environment has driven the research into alternative combustion strategy for internal combustion engines. Low temperature combustion (LTC) concept is a promising approach to achieve higher fuel conversion efficiency along with lower NOx and particulate emissions. Among all the LTC strategies, reactivity controlled compression ignition (RCCI) strategy has potential to mitigate the limitations of conventional diesel combustion (CDC) engines. This study provides an overview of different LTC concepts and demonstrates the benefits of the RCCI combustion strategy over other LTC strategies. In present study, the impact of the fuel premixing ratio and fuel injection timing of high reactivity fuel on the combustion and emission characteristics of RCCI engine is investigated. Proportion of fuel premixing and injection events affect the combustion and emission characteristics of RCCI engine. Study shows that the RCCI engine has a lower operating range as compared to CDC strategy, which can be extended by using optimized premixing ratio and fuel injection events. Results show that RCCI combustion strategy has lower NOx and soot emissions as compared to CDC strategy while maintaining higher thermal efficiency. However, RCCI combustion has a higher HC and CO emissions.