Abstract
Hydrogen combustion in the internal combustion engine (ICE) has currently taken part in the transportation industry due to its environmentally friendly and high engine thermal efficiency. Hydrogen direct injection introduction in the internal combustion engine eliminates the harmful emission from carbon and improves engine stability. The substitution from nitrogen to noble gases for the intake will solve the high auto-ignition temperature of hydrogen in compression ignition (CI) engine problem. This paper intended to study the combustion characteristics of direct injection hydrogen in oxygen-noble gas atmosphere such as argon and helium to find the suitable engine and injection parameters for the optimum engine efficiency. The simulation conducted using Converge CFD V2.4 software based on Yanmar NF19K direct injection CI engine. The simulation was done for different oxygen-noble gases such as argon, neon, and helium, while the injection timing and ambient temperature were modified to optimize the hydrogen combustion characteristics. The study found that noble gases help to increase the in-cylinder temperature and ignite the hydrogen. The study also found that early injection timing results in the highest in-cylinder pressure. Besides, increasing ambient temperature for intake decreases the in-cylinder pressure and lengthen the ignition delay. Therefore, the most suitable injection parameter for the most optimum hydrogen combustion characteristics is 380 K ambient temperature, early injection timing at -10°CA, and higher injection pressure. Helium produced higher in-cylinder peak pressure compared to argon due to its high specific heat ratio. Hence, further consideration of helium and good injection strategies should be applied for better engine thermal efficiency.