Potential towards CI Engines with Lower NOx Emissions through Calibration Optimization and Low-Carbon Fuels 2022-01-0511

The continuous improvement of internal combustion engines (ICEs) with strategies that can be applied to existing vehicle platforms, either directly or with minor modifications, can improve efficiency and reduce GHG emissions to help achieve Paris climate targets. Low carbon fuels (LCF) as diesel substitutes for light and heavy-duty vehicles are currently being considered as a promising alternative to reduce well-to-wheel (WTW) CO₂ emissions by taking advantage of the carbon offset their synthesis pathway can promote, which could capture more CO₂ than it releases into the atmosphere. Additionally, some low carbon fuels, like OMEx blends, have non-sooting properties that can significantly improve the NOx-soot tradeoff. The current work studies the calibration optimization of a EU6D-TEMP light-duty engine using various LCFs with different renewable contents with the goal of reduced NOx emissions. The potential of the different fuel calibrations is evaluated under a simplified Worldwide Harmonized Test Procedure (WLTP), which allows an overview of the homologation capabilities of the engine-out emissions as well as provides the base to perform cycle CO₂ analysis. The results of the work indicate that the fuels with higher proportions of renewable content can have CO₂ WTW emissions that are up to 95% lower than current diesel references, while at the same time being capable of engine-out soot emissions comparable to the current diesel baseline while significantly reducing NOx emissions in view of upcoming more stringent criteria pollutants regulations, such as EU7.