Experimental study on the factors influencing performance and emissions of hydrogen internal combustion engines

Hydrogen internal combustion engines (H2-ICEs) have advantages such as clean combustion and zero carbon emissions, and have become one of the important technical routes for decarbonization in the internal combustion engine industry. In this paper, several key factors affecting the performance and emissions of hydrogen internal combustion engines, such as ignition timing, excess air coefficient, and hydrogen injection timing, were systematically studied on a spark ignition multi-point injection (MPI) hydrogen internal combustion engine bench. The experimental results indicate that the ignition timing controls the combustion phase of hydrogen. Moderate early ignition can improve the brake thermal efficiency (BTE) while having little impact on the NOX emissions. Excess air coefficient(λ) can significantly affect the performance and emissions of H2-ICE. Along with the increase of the λ, the NOX emissions first increases and then continues to decline. When the λ reaching 2.1 or above, near zero emissions of NOX can be achieved. The advance of hydrogen injection timing will slightly increase the peak of cylinder pressure and instantaneous heat release rate. However, overall, the impact of hydrogen injection timing on BTE and NOX emissions is not significant on MPI H2-ICE.