A study of the effect of hydrogen injection pressure on the characteristics of a diesel-ignition hydrogen linear engine

Hydrogen injection pressure is crucial for optimizing combustion efficiency and improving engine dynamics. Therefore, this study utilizes the interaction between piston motion and combustion to establish a coupled model. An iterative algorithm is used to update the calculation results, and the diesel-ignition technology is invoked to investigate the effect of hydrogen injection pressure on the characteristics of hydrogen linear engine (HLE). The results indicate that injection pressure significantly influences the HLE. Compared with the injection pressure of 1.5 MPa, the turbulent kinetic energy at 2.1 MPa increases by 12.48%, and the fuel–air mixing mass fraction rises by 8%. This can promote the airflow movement in the cylinder, which is conducive to sufficient fuel mixing and efficient combustion in the cylinder. In terms of combustion heat release, the cumulative heat release at 2.1 MPa increases by 8.1%, and its heat release rate is also the highest. However, compared with the 1.5 MPa case, the in-cylinder pressure is relatively low, while the peak temperature is higher, whereas above 2.1Mpa, the turbulent kinetic energy decreased by 9.8%, and the degree of fuel mixing was weakened. In addition, its nitrogen oxide and soot emissions are relatively low. This indicates that the hydrogen injection pressure of 2.1Mpa can balance the mixture uniformity and combustion stability, optimize the combustion efficiency, reduce the emission, and then improve the overall performance.