Vinh Nguyen Duy

This study uses the AVL-BOOST simulation platform to investigate the influence of the compression ratio on the operating characteristics of hydrogen-fuelled internal combustion engines. Due to hydrogen’s distinct chemical and combustion properties, specific adjustments are necessary during the modelling process to ensure accuracy. For instance, the ignition timing of the hydrogen engine model must be advanced to approximately 10 degrees before top dead centre, and the combustion duration is significantly shorter compared to conventional hydrocarbon fuels. The analysis reveals that, under stoichiometric conditions (excess air coefficient λ = 1) and across different engine speeds, variations in compression ratio exert a notable impact on several critical performance indicators, including indicated work output, fuel consumption rate, and the in-cylinder pressure and temperature profiles during the combustion process. Furthermore, the formation of nitrogen oxides (NOx) is shown to be highly sensitive to changes in both compression ratio and engine speed, reflecting the strong dependence of NOx production on peak combustion temperature. The simulation results provide insight into the thermodynamic behaviour of hydrogen engines and underline the distinct characteristics of hydrogen as a fuel. With its rapid combustion rate, wide flammability limits, and potential for near-zero carbon emissions, hydrogen demonstrates great promise as a sustainable and environmentally friendly alternative fuel for future transportation systems.