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<p>This study presents a numerical investigation of ammonia–diesel combustion. A 3D CFD model is developed, incorporating chemical kinetics, spray breakup, and droplet vaporization. The model is validated against experimental measurements. The simulation uses the RANS approach with a Eulerian–Lagrangian framework for gas–liquid interactions. Turbulence is modeled using the RNG <i>k–ε</i> model. Four injection timings (− 14°, − 16°, − 18°, and − 20° CA) are validated for an ammonia substitution ratio of 40%. A parametric study is then performed for higher substitution ratios: 50%, 60%, 70%, and 80%. The model successfully captured the fundamental combustion phenomena including air–fuel mixing, ignition delay, flame propagation, and heat release under varying ammonia substitution ratios (A50–A80). Results show that increasing ammonia content prolongs ignition delay (CA10 increased from 1.0 to 8.01° CA) leading to a retarded combustion phasing (CA50 shifted from 11.0 to 19.01° CA). The high autoignition temperature and low reactivity of ammonia tend to delay ignition, which can lead to lower peak pressure and heat release rates, especially in the premixed combustion phase. Findings show that 80% of ammonia is the upper limit for diesel substitution at an engine regime of (910&#xa0;rpm) and 50% engine load.</p>

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Impact of ammonia energy ratio on combustion characteristics, energy efficiency, and emissions in a dual-fuel ammonia/diesel engine

  • 期刊论文

  • 发表日期：

    2026年7月30日

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  • Fathi Hamdi,
  • Samuel Molima,
  • Takwa hamdi,
  • Mouldi Chrigui

摘要

This study presents a numerical investigation of ammonia–diesel combustion. A 3D CFD model is developed, incorporating chemical kinetics, spray breakup, and droplet vaporization. The model is validated against experimental measurements. The simulation uses the RANS approach with a Eulerian–Lagrangian framework for gas–liquid interactions. Turbulence is modeled using the RNG k–ε model. Four injection timings (− 14°, − 16°, − 18°, and − 20° CA) are validated for an ammonia substitution ratio of 40%. A parametric study is then performed for higher substitution ratios: 50%, 60%, 70%, and 80%. The model successfully captured the fundamental combustion phenomena including air–fuel mixing, ignition delay, flame propagation, and heat release under varying ammonia substitution ratios (A50–A80). Results show that increasing ammonia content prolongs ignition delay (CA10 increased from 1.0 to 8.01° CA) leading to a retarded combustion phasing (CA50 shifted from 11.0 to 19.01° CA). The high autoignition temperature and low reactivity of ammonia tend to delay ignition, which can lead to lower peak pressure and heat release rates, especially in the premixed combustion phase. Findings show that 80% of ammonia is the upper limit for diesel substitution at an engine regime of (910 rpm) and 50% engine load.