The effect of different charging concepts on hydrogen fuelled internal combustion engines

Hydrogen has been widely acknowledged as a potential fuel for internal combustion engines, owing to its unique chemical properties, environmental friendliness, and the ability to be produced from a variety of sources. The carbon-free nature of hydrogen is of particular significance as it is considered to be a key contributor to achieving stringent emissions regulations. However, one of the challenges associated with hydrogen as a fuel is the requirement for high air flow during combustion, which is necessary to meet the stoichiometry of the combustion process. The failure to achieve this high air flow can result in elevated emissions of Nitrogen Oxides (NOx), a phenomenon that is of concern for engine manufacturers. Turbocharging increases the power and efficiency of internal combustion engines by forcing more air into the combustion chamber. This can be particularly beneficial for hydrogen-fuelled engines as hydrogen has a lower energy density compared to traditional fossil fuels. This study aims to establish the most efficient boosting strategy for hydrogen-fuelled internal combustion engines with the goal of achieving a combination of fuel economy, high power density, and low emissions of NOx. To achieve this objective, a model of a hydrogen-fuelled internal combustion engine, specifically tailored for heavy-duty vehicle applications and featuring a direct injection system, has been developed. The validity of the model has been evaluated through a comparison of the results obtained from the model with those obtained from dynamometer testing. The study employs a model-based approach to examine a variety of charging concepts. •Hydrogen engine has very low NOx emission above cylinder mass ratio of 2.4.•High air mass is required to satisfy low engine NOx emission.•Charging concepts for hydrogen engine can satisfy full load targets at sea level.•Variable geometry has highest efficiency, 2-stage has better high altitude margin.