Experimental Investigation into Abnormal Combustion Behaviour in a Pure Hydrogen Spark-Ignition Engine

The hydrogen internal combustion engine technology, with its potential for almost full carbon emissions reduction and adaptability to a wide range of fossil fuel-based internal combustion engine (ICE) platforms, offers a promising future. This potential underscores the importance of the research, which aims to address the challenges, such as abnormal combustion phenomena, that come with this innovative technology. These challenges, including intake backfire in the port fuel injection (PFI) and preignition, require further investigation to fully understand and predict the engine's performance. This study comprehensively investigates the main abnormal combustion behaviour in a spark ignition (SI) downsized boosted hydrogen engine. It examines both direct and port fuel injection (DI and PFI) systems, evaluating in-cylinder, intake, and exhaust pressures in the crank domain. The study provides a direct comparison at steady-state conditions between abnormal and normal cycles over 200 cycles and uses ultra-fast NOx, HC, and CO2 emissions analysers to delve deep into the preignition phenomenon. The main outcomes of this study are significant. The study reveals new parameters for understanding the overshooting pressure rise rates and the frequency of preignition. This understanding is crucial for further research and development in the field. The study also shows that the NOx overshoot can help estimate the peak cylinder temperature of the cycles with preignition events. Furthermore, adopting the DI systems prevents intake back pressure completely. Finally, by recording the CO and HC in the crank domain, the study demonstrates the difference between preignition caused by excessive lubricant oil and preignition due to hotspot areas in the combustion chamber, which results in a lower overshooting peak pressure by 16%.