Computational evaluation of the combustion chamber geometry and applying syngas in a heavy-duty off-road Reactivity Controlled Compression Ignition (RCCI) engine

This numerical research conducted using CONVERGE Computational Fluid Dynamic (CFD) code and devoted to assessing the simultaneous and separate impacts of Diesel Direct Injection Timing (DDIT) (16 to 6 Crank Angle (CA) Before Top Dead Center (BTDC) with 2 CA steps), combustion chamber geometry (re-entrant (baseline), cylindrical, and wide-shallow chamber), and applying syngas (20 and 40% of total energy per cycle) in a heavy-duty off-road RCCI engine. In the case of combustion simulation, the SAGE combustion model was used coupled with a detailed chemical kinetic mechanism consist of 72 species and 360 reactions. Results showed that under baseline operating conditions (DDIT of 10 CA BTDC and using re-entrant piston bowl) increasing the syngas to diesel ratio up to 40% caused a 3.4% rise in heat transfer loss and simultaneous reduction in Nitrogen Oxides (NOx) about 12%, Particulate Matter (PM) up to 88%, and Hydro-Carbons (HCs) nearly 82% compared to Pure Diesel Combustion (PDC) conditions. Besides, utilizing the wide-shallow combustion chamber along with diesel injection at 16 CA BTDC at diesel- 40% syngas combustion operating conditions led to the increment of heat transfer loss (7%), combustion loss (2.5%), and also, simultaneous reduction of NOx (3%), PM (37%), HC (62%), and gross indicated efficiency (4.7%) compared to baseline PDC case.