Validation of a CFD hydrogen combustion model on an PFI SI engine under lean combustion 2023-36-0125

In order to further explore the potential of hydrogen as an alternative fuel, this study aims to validate a computational fluid dynamics model for hydrogen combustion in a port fuel injection spark ignition engine. The engine operates at 1800 rpm with a compression ratio of 10:1, under two lean combustion conditions: excess air ratios of 2.5 and 1.7, at full and part load, respectively. The simulations were performed using the CONVERGE 3.1 software and the C3MechV3.3 reaction mechanism. The predictions were then compared with experimental data to assess the accuracy and validity of the model, enabling the comparison of different lean operating conditions to evaluate important combustion characteristics, such as flame development, apparent heat release and NO_x formation. The tested model successfully validated the two experimental conditions, accurately adjusting the in-cylinder pressure profiles for both cases of lean hydrogen mixture combustion. Additionally, the prediction of the apparent heat release rate was corrected, with the partial load condition and ignition timing set to a more favorable charge thermal state, which resulted in faster and lower-intensity heat release compared to the leaner mixture condition at full load. Finally, regarding thermal NOx formation, the model successfully predicted the higher formation in the λ= 1.7 condition, while the λ = 2.5 condition resulted in near-zero NOx. The validated CFD model provides valuable insights for designing efficient and environmentally friendly hydrogen-fueled engines, contributing to the development of carbon-free transportation solutions.