Nowadays hydrogen, especially if derived from biomass or produced by renewable
power, is rising as a key energy solution to shift the mobility of the future
toward a low-emission scenario. It is well known that hydrogen can be used with
both internal combustion engines (ICEs) and fuel cells (FCs); however,
hydrogen-fuelled ICE represents a robust and cost-efficient option to be quickly
implemented under the current production infrastructure. In this framework, this
article focuses on the conversion of a state-of-the-art 3.0L diesel engine in a
hydrogen-fuelled Spark Ignition (SI) one. To preliminarily evaluate the
potential of the converted ICE, a proper simulation methodology was defined
combining zero-, one-, and three-dimensional (0D/1D/3D) Computational Fluid
Dynamics (CFD) approaches. First of all, a detailed kinetic scheme was selected
for both hydrogen combustion and Nitrogen Oxides (NOx) emission predictions in a
3D-CFD environment. Afterward, to bring the analysis to a system-level approach,
a 1D-CFD predictive combustion model was firstly optimized by implementing a
specific laminar flame speed correlation and, secondly, calibrated against the
3D-CFD combustion results. The combustion model was then integrated into a
complete engine model to assess the potential benefit derived from the wide
range of flammability and the high flame speed of hydrogen on a complete engine
map, considering NOx formation and knock avoidance as priority parameters to
control. Without a specific modification of turbocharger and combustion systems,
a power density of 34 kW/L and a maximum brake thermal efficiency (BTE) of about
42% were achieved, thus paving the way for further hardware optimization (e.g.,
compression ratio reduction, turbocharger optimization, direct injection [DI])
to fully exploit the advantages enabled by hydrogen combustion.
