Real World Diesel Engine Greenhouse Gas Emissions for Diesel Fuel and B100

The transport sector is one of the major contributors to greenhouse gas emissions. This study investigated three greenhouse gases emitted from road transport using a probe vehicle: CO₂, N₂O and CH₄ emissions as a function temperature. It should be highlighted that methane is a greenhouse gas that similarly to carbon dioxide contributes to global warming and climate change. An oxidation catalyst was used to investigate CO₂, N₂O and CH₄ GHG emissions over a real-world driving cycle that included urban congested traffic and extra-urban driving conditions. The results were determined under hot start conditions, but in congested traffic the catalyst cooled below its light-off temperature and this resulted in considerable N₂O emissions as the oxidation catalyst temperature was in the N₂O formation band. This showed higher N₂O during hot start than for diesel fuel and B100 were compared. The B100 fuel was Fatty Acid Methyl Ester (FAME), derived from waste cooking oil, which was mainly RME. A multifunctional additive package was added at 800 ppm to control fuel injector deposit formation. GHG emissions were monitored using an on-board heated Temet FTIR exhaust emission analyzer. A Horiba onboard emissions-measuring system was also used to measures the exhaust mass flow rate together with air/fuel ratio. 172 g/km was the certified CO₂ value based on the standard test cycle and in the real-world driving the vehicle's CO₂ was similar. Methane emissions were negligible, and N₂O emissions were higher than for SI engines with a TWC, which was not expected, but this was due to the lower catalyst temperatures and the more frequent occurrence of stop/start events in congested traffic.