Effects of methanol-containing additive on emission characteristics from a heavy-duty diesel engine

This study was aimed to investigate the effect of methanol-containing additive ŽMCA. on the regulated emissions of hydrocarbons ŽHC., carbon monoxide ŽCO., nitrogen oxides ŽNOx., particulate matter ŽPM., as well as the unregulated carbon dioxide ŽCO2. and polycyclic aromatic hydrocarbons ŽPAHs. from a diesel engine. The engine was tested on a series of diesel fuels blended with five additive levels Ž0, 5, 8, 10 and 15% of MCA by volume.. Emissions tests were performed under both cold- and hot-start transient heavy-duty federal test procedure ŽHD-FTP. cycles and two selected steady-state modes. Results show that MCA addition slightly decreases PM emissions but generally increases both THC and CO emissions. Decrease in NOx emissions was found common in all MCA blends. As for unregulated emissions, CO2 emissions did not change significantly for all MCA blends, while vapor-phase and particle-associated PAHs emissions in high load and transient cycle tests were relatively low compared to the base diesel when either 5 or 8% MCA was used. This may be attributed to the lower PAHs levels in MCA blends. Finally, the particle-associated PAHs emissions also showed trends quite similar to that of the PM emissions in this study.