Comparisons of advanced combustion technologies (HCCI, PCCI, and dual-fuel PCCI) on engine performance and emission characteristics in a heavy-duty diesel engine
Advanced combustion technologies (ACTs), which have great potential for nitrogen oxides (NOx) and particulate matter (PM) reduction simultaneously, have been researched steadily to replace conventional diesel combustion (CDC) over the past 40 years. However, it is still unclear which ACT is suitable as a practical alternative combustion technology. In this study, single-fueled and dual-fueled ACTs, such as homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI) and dual-fuel premixed charge compression ignition (DF-PCCI), were implemented to compare with each other in a heavy-duty single cylinder engine under a specified load condition at which all ACTs can be operated stably. The combustion characteristics, emission performance, thermal efficiency (eta(T)), and combustion efficiency (eta(c)) were considered as comparative factors in order for the comparative evaluations of among the three ACTs. The results showed that all ACTs could reduce the NOx and PM emissions simultaneously under the EU-VI NOx and PM regulations without after-treatment system. In addition, DF-PCCI combustion has achieved indicated thermal efficiency (ITE) of 45.3%, which was higher than that for CDC, due to the superior controllability of combustion phase and burn duration. However, DF-PCCI combustion produced high amounts of total hydrocarbon (THC) and carbon monoxide (CO) emissions which could deteriorate the combustion efficiency. These results suggest that although the DF-PCCI combustion technology has various strengths, such as high thermal efficiency and superior combustion controllability, the combustion efficiency should be improved through THC and CO reductions in order to become a practical combustion technology.