Modern gasoline direct-injection engines: Key challenges and mitigation pathways: A critical review

Gasoline Direct Injection (GDI) engines have become a cornerstone of modern automotive technology due to their significant advancements in fuel efficiency, emissions reduction, and combustion optimization. However, challenges remain in managing particulate emissions, improving engine performance, and addressing knocking phenomena. This review explores the latest developments in GDI engine technologies, focusing on pathways for enhancing combustion stability, reducing emissions, and optimizing engine performance across various operating conditions. Key technologies such as Exhaust Gas Recirculation (EGR), Gasoline Particulate Filters (GPFs), have been instrumental in addressing the emission challenges. Moreover, alternative fuels like ethanol, methanol, and hydrogen have been explored for their potential to improve combustion efficiency and reduce emissions. The review also discusses various injection strategies, including single, double, dual-fuel, and water injection, as well as the promising role of flash boiling in improving fuel atomization and mixture homogeneity. Despite these advancements, the review identifies several ongoing research gaps, particularly in optimizing injection systems and improving the fuel blends. The paper concludes by highlighting the need for continued research into hybrid systems and advanced modeling techniques to further improve GDI engine performance while meeting increasingly stringent emissions regulations.