Alternative fuels and aftertreatment systems for low emissions engines

This research provides an understanding of the synergies between the combustion of bio-oxygenated fuels and thermal management of the aftertreatment systems for the control of diesel gaseous and particulate matter emissions.
Blends of diesel with bio-alcohols and a bio-ketone with different molecular structure including butanol, pentanol, cyclopentanol and cyclopentanone proved to be promising alternative fuels in terms of energy density, viscosity, lubricity, tribological mechanisms, combustion behaviour and emissions reduction. Using bio-oxygenated fuels with a higher polarity (mainly cyclic compounds) resulted in lower wear scar size by up to 38%, compared to the diesel baseline, during the lubricity test. Engine-out hydrocarbons and particulate matter emissions were lower by up to 37% and 91%, respectively. The modified exhaust gas composition from the combustion of the aforementioned oxygenated fuel blends, improved the catalyst oxidation reactions, and light-off was achieved at lower exhaust gas temperatures.
Furthermore, an active control strategy of heating the aftertreatment system was studied. Due to reduced catalyst light-off temperature when using the alternative fuels for combustion, e.g. by up to 26 °C for CO, a lower heater energy input was required for the catalytic light-off when compared to diesel combustion only. Importantly, modifying the exhaust gas composition of the diesel baseline by adding 500 ppm of H2 gas upstream of the catalyst decreased the CO light-off temperature by approximately 50 °C.