Effects of fuel injection strategies in a RCCI heavy-duty diesel engine


The main goal of the present study was to explore the impacts of various fuel injection strategies in a heavy-duty Direct Injection (DI) diesel engine operating under diesel-syngas combustion conditions computationally using CONVERGE Computational Fluid Dynamic (CFD) code. The SAGE combustion model coupled with a chemical kinetic n-heptane/toluene/PAH (Poly-Aromatic Hydro-carbons) mechanism that consisted of 71 species and 360 reactions were used to simulate the diesel-syngas combustion process and the formation and oxidation of emissions, e.g., Nitrogen Oxides (NOx), Particulate Matter (PM), Carbon Monoxide (CO), and Unburnt Hydro-Carbons (UHC). The separate effects of main (8 to 18 Crank Angle (CA) Before Top Dead Center (BTDC) with 2 CA steps) and post-injection (35 to 55 CA (After Top Dead Center) ATDC with 5 CA steps) timing of diesel fuel on the combustion characteristics and exhaust gas emissions were investigated under diesel-syngas combustion conditions. The numerical achievements revealed that the substitution part of the diesel with a CO–H2 gaseous mixture led to a considerably lower PM and UHC emissions in the exhaust gases with a CO penalty rate. Maximum Combustion Temperature (MCT) and Heat Release Rate Peak Point (HRRPP) were increased as Main-Injection Timing (MIT) was advanced. Also, advancing MIT led to a considerably higher level of NOx emissions but lower PM formation. Moreover, compared to baseline engine operating conditions, post-injection of diesel at 35 CA ATDC reduced both PM and UHC emissions simultaneously by nearly 26.5 and 89%, respectively.

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After top dead center


Before top dead center


Crank angle


Computational fluid dynamic


Carbon monoxide


Direct injection


Duration of injection


Diesel-syngas combustion


Exhaust gas recirculation


Exhaust valve opening


Heat release rate


Heat release rate peak point


Ignition delay


Intake manifold air pressure


Intake manifold air temperature


Injection timing


Intake valve close


Low temperature combustion


Maximum combustion temperature


Main-injection timing


Nitrogen oxides


Poly-aromatic hydrocarbon


Post-injection pressure


Post-injection quantity


Post-injection timing


Particulate matter


Reactivity controlled compression ignition


Re-normalisation group


Ringing intensity


Revolution per minute


Start of injection


Top dead center


Unburnt hydro-carbon


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This research work was supported by a research grant from the Amol University of Special Modern Technologies, Amol, Iran.

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Correspondence to Bahram Jafari.

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Jafari, B., Seddiq, M. Effects of fuel injection strategies in a RCCI heavy-duty diesel engine. Sādhanā 46, 6 (2021). https://doi.org/10.1007/s12046-020-01527-7

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  • Combustion simulation
  • RCCI engine
  • fuel injection
  • syngas
  • emissions