Exploring sustainable fuel alternatives: The role of NH3–H2–H2O2 blends in enhancing HCCI engine performance

This study presents a comprehensive computational analysis of Homogeneous Charge Compression Ignition (HCCI) engines fueled by a carbon-free blend of ammonia (NH₃), hydrogen (H₂), and hydrogen peroxide (H₂O₂). The research aims to explore the potential of this blend in enhancing combustion performance and reducing emissions, addressing the critical challenge of environmental sustainability in internal combustion engines. Through the use of detailed kinetic modeling and three-dimensional computational fluid dynamics (CFD), the impacts of various blend compositions on key engine performance was assessed. The kinetic model is validated with the published literature data. The findings indicate that the addition of H₂O₂ significantly improves autoignition and the combustion duration of an NH₃–H₂ blend in an HCCI engine is 17° at 515 K. However, with the addition of 40% H₂O₂, the combustion duration reduces to approximately 16°, even at lower temperatures (395 K). The introduction of 40% H₂O₂ in the NH₃–H₂ HCCI engine results in a 12.8% increase in output power and a 22.2% decrease in NO_x emissions due to the reduced operating temperature under Maximum Brake Torque (MBT) conditions. With a fuel blend of NH₃-0.7, H₂-0.2, and H₂O₂-0.1 at an inlet temperature of 450 K, the combustion duration (CD) is 22°. Increasing hydrogen to 50% and reducing the inlet temperature to about 390 K decreases the CD to 5°. This study demonstrates that the NH₃–H₂–H₂O₂ blend holds significant promise as a viable alternative to conventional fuels, potentially contributing to the advancement of zero-carbon emission combustion technologies in future transportation systems.