Effect of Timing Strategy on Mixture Formation, Performance and Emission of Inlet Injection Hydrogen Engine

In order to scrutinize the timing variables impacting the combustion performance and emissions of the Port Fuel Injection hydrogen engine (PFI-H2ICE), a model of a four-cylinder hydrogen engine is meticulously built utilizing the 1D software GT-POWER. The effect of excess air coefficients and timing strategies (including the intake valve opening timing (IVO), the start of injection timing (SOI), and ignition timing) is analyzed in this study. The main conclusions are as follows: The hydrogen engine remold from the Isuzu JE4N28 nature gas engine manifests a lean combustion threshold ranging between 2.0 and 2.5. Notably, advancing intake valve opening timing by 20°CA has proven beneficial to the brake thermal efficiency (BTE) of the hydrogen engine while reducing the NOx emissions by a substantial margin, and advancing intake valve opening timing bears the virtue of strengthen the positive influence of the start of injection timing upon the engine's combustion performance. The longer the formation duration of the air-fuel mixture from the start of hydrogen injection timing to the ignition timing enables the better the combustion performance of the engine and the lower the NOx emissions. The outside-cylinder mixing time shows a stronger impact on the brake thermal efficiency, whereas the inside-cylinder mixing time has a greater impact on NOx emissions. The influence level of ignition timing, start of injection timing, and intake valve opening timing upon the combustion performance and emissions of the hydrogen engine decreases successively.