As biofuels are increasingly represented in the fuel market, the use of these oxygenated fuels should be evaluated under various engine operating conditions, such as cold-start. However, to-date quantification has been mostly done under hot-start engine operation. By using a custom test designed for this study, a comparative investigation was performed on exhaust emissions during cold- and hot-start with diesel and three oxygenated fuels based on waste cooking biodiesel and triacetin. This study used a six-cylinder, turbocharged, after-cooled diesel engine with a common rail injection system. The results during cold-start with diesel showed lower NOx (up to 15.4%), PN (up to 48%), PM 1 (up to 44%) and PM 2.5 (up to 63%). However, the oxygenated fuels during cold-start showed a significant increase in NOx (up to 94%), PN (up to 27 times), PM 1 (up to 7.3 times) and PM 2.5 (up to 5 times) relative to hot-start. The use of oxygenated fuels instead of diesel during hot-start decreased the PN, PM 2.5 and PM 1 (up to 91%) while, during cold-start, it only decreased PM 1 and PM 2.5 at some engine operating modes and increased PN significantly up to 17 times. In both cold- and hot-start, the use of oxygenated fuels resulted in an increase in NOx emission. For cold-start this was up to 125%, for hot-start it was up to 13.9%. In comparison with hot-start, the use of oxygenated fuels during cold-start increased nucleation mode particles significantly, which are harmful. This should be taken into consideration, since cold-start operation is an inevitable part of the daily driving schedule for a significantly high portion of vehicles, especially in cities.
- Fuel oxygen content
- Particle size distribution
Zare, A., Nabi, M. N., Bodisco, T. A., Hossain, F. M., Rahman, M. M., Chu Van, T., ... Brown, R. J. (2017). Diesel engine emissions with oxygenated fuels: A comparative study into cold-start and hot-start operation. Journal of Cleaner Production, 162, 997-1008. https://doi.org/10.1016/j.jclepro.2017.06.052