Numerical Investigation of Ammonia-Diesel Fuelled Engine Operated in RCCI Mode

Ammonia, which is one of the most produced inorganic chemicals worldwide, has gained significant attention in recent years as a carbon-free fuel due to its significant energy density in maritime and power plant applications. This fuel offers several advantages including low production costs and being safe for storage and transport. Reactivity controlled compression ignition (RCCI) combustion mode is considered as a promising strategy reducing the level of nitrogen oxides (NOx) emissions and particulate matters (PM) in internal combustion engines (ICEs) due to the lower combustion temperatures and charge homogeneity. Ammonia-based RCCI combustion strategy can offer a simultaneous reduction of CO₂ and NO_x. In this study, a RCCI engine fuelled by ammonia and diesel is numerically simulated considering chemical reactions kinetics mechanism of the combustion. After validating the simulation results with literature experimental data, the effect of engine operational parameters such as the initial charge temperature together with injection timing on the engine operational characteristic including in-cylinder pressure, heat release rate (HRR), indicated mean effective pressure (IMEP) and emission levels are investigated and discussed accordingly. The results indicated that advancing the start of injection (SOI) timing from 20 to 100 CAD bTDC, increased the NOx emissions concentration at the initial intake charge temperatures of 460 and 480 K. Higher initial intake charge temperature increased the level of NOx emissions while advancing SOI timing from 20 to 100 CAD bTDC did not disturb the level of CO emission significantly.