Simulation Analysis of a Spark-Ignition Engine Fueled with Gasoline and Hydrogen

The decarbonization of transport demands efficient, low-carbon alternatives to conventional fuels, particularly in regions where full electrification remains constrained. This study investigates the retrofitting of a 1.3 L Geely MR479Q spark-ignition engine for hydrogen operation, combining experimental measurements and one-dimensional numerical simulations in GT-SUITE. The baseline gasoline model was experimentally validated in 12 operating conditions and extended to the full map. In addition, the fuel was changed in the numerical model, and evaluations of hydrogen combustion through predictive sub-models considering mixture formation and pressure-rise limits were performed. Results show that the hydrogen engine operates stably within a wide air–fuel ratio window (λ = 1.0–2.7), with brake thermal efficiencies peaking at approximately 29%, surpassing gasoline operation by up to 5% in the mid-load range. However, port fuel injections cause a reduction in volumetric efficiency and maximum power output due to air displacement, a limitation that could be mitigated by adopting direct injection. A practical hydrogen conversion kit was defined—including injectors, cold-type spark plugs, electronic throttle, and programmable ECU—and the operational cost was analyzed. Economic parity with gasoline is achieved when hydrogen prices fall below ~6 USD kg−1, aligning with near-term green-hydrogen projections. Overall, the results confirm that predictive numerical calibration can effectively support retrofit design, enabling efficient, low-emission combustion systems for sustainable transport transitions.