Injection Strategies in a Hydrogen SI Engine: Parameter Selection and Comparative Analysis

Injection strategies play a crucial role in determining hydrogen engine performance. The diversity of these strategies and the limited number of comparative studies highlight the need for further investigation. This study focuses on the analysis, parameter selection, and comparison of single early and late direct injection, single injection with ignition occurring during injection (the so-called jet-guided operation), and dual injection in a hydrogen spark-ignition engine. The applicability and effectiveness of these injection strategies are assessed using contour maps, with ignition timing and start of injection as coordinates representing equal levels of key engine parameters. Based on this approach, injection and ignition settings are selected for a range of engine operating modes. Simulations of engine performance under different load conditions are carried out using the selected parameters for each strategy. The results indicate that the highest indicated thermal efficiencies are achieved with single late injection, while the lowest occur with dual injection. At the same time, both dual injection and jet-guided operation provide advantages in terms of knock suppression, peak pressure reduction, and reduced nitrogen oxide emissions.