Comparative investigation on the performance of a heavy-duty spark ignition engine fueled with ethanol and natural gas.

Since the obvious difficulties in realizing a lightweight long-range full electric powertrain, Internal Combustion Engines (ICEs) are still the most suitable solution for heavy-duty mobility. In a fossil fuel free scenario, bio-ethanol is one of the most interesting alternative fuels. Its high-octane number, high latent heat of vaporization and high laminar flame speed guarantee high performance with reduced pollutant emissions compared to other Spark Ignition (SI) engine fuels. However, ethanol evaporation and corrosivity represent quite serious challenges. This work aims at investigating the actual performance of a heavy-duty turbocharged SI ICE fueled with ethanol at full load and different engine speeds. A 1-D numerical model that includes fuel evaporation sub-models was developed in order to evaluate the engine performance, ensuring ethanol evaporation in each operating condition. The 1-D numerical model was validated through an experimental campaign carried out with the above-mentioned engine, fueled with ethanol in a Single Point Injection (SPI) configuration. In particular, ethanol evaporation was guaranteed through the adoption of suitable operating conditions and specific technical solutions. Simulation output have been compared with the results obtained from an experimental campaign carried out with the same engine at the same operating conditions, fueled with natural gas in a Port Fuel Injection (PFI) configuration. An additional engine model characterized by an ethanol PFI system was developed in order to compare the simulation output in the same hardware conditions.