Towards zero-carbon high-altitude operation using hydrogen-fuelled internal combustion engines: Experimental analysis and one-dimensional modelling

The present study analyses the viability of an 11.67-litre turbocharged hydrogen-fuelled internal combustion engine operating at altitudes up to 7500 m. An extensive experimental campaign, involving sweeps of air-fuel ratio ( λ ) and engine speed, provided data to validate a 1D predictive model. The prospective studies compare engine performance at various altitude levels using DI and PFI configurations, demonstrating that DI technology achieves the 150 kW target, enabling operation with superior efficiency. Furthermore, incorporating the ram air effect ensures the viability of the PFI configuration by reducing the pressure ratio (PR) demand on the turbocharger. In addition, the parametric analysis of λ demonstrates the potential to maximize Brake Thermal Efficiency (BTE) up to 39.3% by operating at λ = 2 . 25 . Finally, lean operation is physically limited beyond λ = 2 . 35 by the boosting system’s capacity. These findings provide quantitative guidelines for sizing future high-altitude power units. • 11.67-litre hydrogen engine tested under lean operation for a predictive model. • Injection strategy and ram air effect ensure 150 kW power at 7500 m. • An air-fuel ratio of 2.25 maximizes efficiency up to 39.3 percent at 7500 m. • Boosting system limits lean operation beyond 2.35 air-fuel ratio at 7500 m.