Heavy-duty internal combustion engines (ICEs), including those used in agricultural machinery, are undergoing a transition towards renewable fuels to reduce their environmental impact. In a scenario aiming at complete fossil fuel elimination, bioethanol emerges as one of the most promising alternative fuels, gaining particular attention in agricultural applications, where fuel production can be integrated into farm operations. Bioethanol high octane number, elevated latent heat of vaporization, and fast laminar flame speed enable high engine performance while reducing pollutant emissions compared to conventional spark ignition (SI) engines. However, challenges related to ethanol evaporation must be addressed. In this study, a diesel-derived engine was converted to run on pure ethanol in spark ignition mode using a single-point injection (SPI) system. Unlike conventional flex-fuel engines that run on blends of gasoline and ethanol, this configuration was selected to avoid modifications to the cylinder head and enables the complete elimination of the fossil fuels. A 1D numerical model, which takes into account the droplets and film evaporation as well as wall spray impingement was developed in order to investigate the in-cylinder ethanol evaporation at different fuel injection temperatures (25–100 °C), intake air temperatures (25–115 °C) under both cold and warm engine conditions.
Under cold conditions, results indicate that intake air temperature has a dominant effect on ethanol vaporization. At 115 °C air temperature and 100 °C fuel temperature, the burned vapor fraction reached 66%, compared to 28% at 25 °C air temperature. Under warm engine conditions, the elevated wall temperatures enable complete evaporation of the liquid film, even when intake air and fuel temperatures are low. These findings highlight the critical role of thermal boundary conditions, especially air and wall temperatures, in optimizing mixture preparation and combustion efficiency. The study provides valuable insights for improving cold start strategies and thermal management in ethanol-fueled heavy-duty engines, promoting reliable and efficient operation.