Implementation of thermal and fuel stratification strategies to extend the load limit of HCCI engine

The HCCI engine can be a possible potential engine technology that gives high performance with fewer dangerous exhaust emissions. In HCCI engines, low-temperature combustion of lean, highly premixed charge effectively reduces the NOX and soot. The HCCI combustion allows utilization of a wide variety of fuels and provides higher thermal efficiency like conventional diesel. However, there are several practical challenges observed in HCCI combustion which limits HCCI engine operations to part-load conditions only. These challenges are; combustion phase control, abnormal pressure rise, and high levels of HC and CO emissions, cold start and homogeneous charge preparation, etc. The thermal and fuel stratification strategies, coupled to combustion phase control are introduced to address these issues. This paper reviews the methods to achieve the in-cylinder thermal and fuel stratifications, implementation with combustion phasing control parameters such as fuel injection timings, intake temperature, DI ratio, and EGR rate, and their effects on engine performance, and emissions.