A Review on Recent Developments of RCCI Engines Operated with Alternative Fuels

Environmental concerns over automotive exhaust emissions and consumer demand for higher fuel efficiency have led to the development of low-temperature combustion concepts. The reactivity-controlled compression ignition (RCCI) engine is one among them and has the potential to reduce NOx and smoke emissions simultaneously. In this concept, a low-reactivity fuel is injected into the intake port and another high-reactivity fuel is injected into the cylinder directly. This results in reactivity stratification and provides more control over the rate of heat release. However, operating parameters such as reactivity of fuels, premixing ratio, injection strategies, exhaust gas recirculation ratio, piston bowl geometry, and compression ratio influence emissions formation. The article reviews recent developments on the effect of the above operating parameters on the performance and emission characteristics of RCCI engines operated with alternative fuels. The combustion strategies used to extend the RCCI mode to higher loads are also reviewed. Applications of computational fluid dynamics (CFDs) to design the combustion chamber for RCCI engines are discussed. The need for further improvements in the CFD models for RCCI engines is explained. After presenting a thorough review of recent literature, directions for future research on RCCI engines are proposed.

Automated summary

Environmental concerns and fuel efficiency demands have led to the development of low-temperature combustion concepts, including the reactivity-controlled compression ignition (RCCI) engine, which can reduce NOx and smoke emissions. This article reviews recent research on the effect of operating parameters on the performance and emissions of RCCI engines using alternative fuels. It also discusses combustion strategies to extend the RCCI mode to higher loads and the application of computational fluid dynamics (CFDs) for designing RCCI engine combustion chambers, highlighting the need for further improvement in CFD models. Directions for future research on RCCI engines are proposed based on a thorough literature review.