Hydrogen-fuelled internal combustion engines: direct injection versus port-fuel injection

Abstract

The road-transport is one of the major contributors to greenhouse global gas (GHG) emissions, where hydrogen (H2) combustion engines can play a crucial role in the path towards the sector's decarbonization goal. This study focuses on comparing the performance and emissions of port-fuel injection (PFI) and direct injection (DI), in a spark ignited combustion engine when is fuelled by hydrogen and other noteworthy fuels like methane and coke oven gas (COG). Computational fluid dynamic simulations are performed at optimal spark advance and air-fuel ratio (^) for engine speeds between 2000 and 5000 rpm. Analysis reveals that brake power increases by 40% for DI, attributed to 30.6% enhanced volumetric efficiency, while the sNOx are reduced by 36% compared to PFI at optimal (^) = 1.5 for hydrogen. Additionally, H2 results in 71.8% and 67.2% reduction in fuel consumption compared to methane and COG respectively, since the H2 lower heating value per unit of mass is higher.