Hydrogen driven HCCI engine combustion and performance indices: a numerical investigation

Interest in hydrogen-powered engines is growing due to their potential to reduce greenhouse gas emissions and decrease reliance on fossil fuels. This research examines how the start of combustion (SOC) impacts the performance of homogeneous charge compression ignition (HCCI) engines using hydrogen exclusively. Using numerical simulations with a 0D multi-zone HCCI model, the study investigates parameters such as compression ratio (CR), equivalence ratio (ER), and intake charge temperature (ICT) to assess their influence on engine performance. The results uncover hydrogen's unique combustion behaviour, characterised by its physiochemical properties and low-temperature combustion. The study identifies an optimal ER range of 0.1 to 0.3, with various ICTs and it is playing a pivotal role in promoting auto-ignition and accelerating combustion. However, an ER of 0.4 and ICT of 393 K produces relatively higher indicated thermal efficiency, which is affected by knocking due to a higher rate of pressure rise, constraining the ER range. Additionally, the research explores the potential of charge dilution to expand the ER range in HCCI mode. These insights provide valuable guidance for enhancing the operation of hydrogen-fuelled HCCI engines, facilitating the transition to cleaner and more efficient propulsion systems in transportation.