Experimental and Numerical Investigation of a Single-Cylinder Methanol Port-Fuel Injected Spark Ignition Engine for Heavy-Duty Applications

With the increasing focus on reducing CO₂ emissions to combat global warming and climate change, the automotive industry is exploring near zero-emission alternative fuels to replace traditional fossil-based fuels like diesel, gasoline, and CNG. Methanol is a promising alternative fuel that is being evaluated in India due to its easy transportation and storage, as well as its production scalability and availability potential. This study focuses on the retro-fitment solution of M100 (pure methanol) SI port-fuel injection (PFI) mode of combustion. A heavy duty single-cylinder engine test setup was used to assess methanol SI combustion characteristic. Lean operation strategy has been investigated. At lean mixture conditions a significant drop in NO_X and CO emissions was achieved. The fuel injection techniques and the impact of exhaust gas recirculation (EGR) on the conventional stoichiometric combustion process is highlighted. Increase of the EGR ratio at stoichiometric operation led to 3% improvement in the thermal efficiency. The typical knock behaviour of the premixed combustion systems is analysed with different ignition sweep and EGR ratio. A higher EGR ratio is found to be beneficial in suppressing the knocking tendency. Moreover, NO_X emission well below 2 g/kWh were achieved, of adherence to the major emission legislations. The characteristics of engine aftertreatment are broadly discussed by analysing the engine out emission and operating condition. The article also focuses on development of the validated model using the Computational Fluid Dynamics (CFD) approach. The CFD investigation helps to understand and give insight of the evaporation challenges and wall-film formation at the critical engine components. Overall, the study provides an outlook into the combustion process and system layout of PFI methanol engines for retro fitment from base diesel engine, demonstrating their potential for improved engine performance and reduced emissions.