S. Talesh Amiri - Department of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran
R. Shafaghat - Department of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran
O. Jahanian - Department of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran
A. H. Fakhari - Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran

To better homogenize the mixture of fuel and air in the combustion chamber and to enhance the controllability of ignition timing in Reactivity Controlled Compression Ignition (RCCI) engines, controlling the start of injection (SOI) timing can be essential. By changing the SOI timing, at some specific crank angles (CAs), the fuel can impact the edge of the piston bowl and create some difficulties. In this research, initially, efforts are made to recognize the range of SOI timing in which this collision process takes place (in the range of 44-54° bTDC), then, performance and the emission levels of the engine were evaluated in the beginning and end of this interval. The findings suggest that the nitrogen oxides emissions and the maximum in-cylinder mean pressure are higher in SOI of 44° bTDC, as compared to those in the SOI timing of 54°bTDC, although the latter has higher ignition delay and unburnt hydrocarbon (UHC) emission. Moreover, some evaluations were carried out to examine how the temperature of the fuel-air mixture can affect the performance of the engine in this specific range. It was found that as the IVC temperature increases, it rises the indicated mean effective pressure (IMEP), in-cylinder pressure, and NOx emission.

Intake valve closing temperature, NOx, Piston bowl rim edge, Reactivity controlled compression ignition, Thermal efficiency, Unburnt hydrocarbon