Using the DOE Concept to Determine the Appropriate Operating Conditions for the D87 Heavy-Duty Diesel Engine under RCCI Combustion Fueled with Diesel Fuel and Natural Gas

The main purpose of this study is to determine the appropriate operating conditions for Iranian national heavy-duty diesel engines under RCCI combustion fueled with natural gas and diesel fuel. Therefore, in the RCCI combustion simulation, based on the DOE concept, the effect of changing six major parameters namely the IVC pressure, the IVC temperature, the diesel fuel SOI timing, the engine speed, the natural gas/diesel fuel mass ratio, and the effective compression ratio on the engine performance and combustion characteristics were assessed. The simulation results show that considering the IVC pressure between 2.3 and 2.7 bar, the IVC temperature between 350 and 380 K, the diesel fuel SOI timing between -30 and -50 ° ATDC, the NG/diesel fuel mass ratio between 70/30 and 90/10, and the engine speed between 1300 and 1600 rpm lead to optimal D87 engine operation. Where the GIE can be improved to more than 40% compared to the D87 engine operation under the dual-fuel mode of combustion. Although, the engine output power is noticeably reduced up to 17%, , the NOx emission level gets close to the EURO V level and the CO emission level gets close to the EURO VI level. At the same time, the UHC emission level is far from the EURO VI level and the Formaldehyde emission level is far from the EPA 2007 level.