Evaluating the effects of olefin components in gasoline on GDI engine combustion and emissions

Olefins are part of the most important components in gasoline fuel. In this paper, olefin component diisobutylene (DIB), 1-pentene and 1-hexene are involved into research. Three quinary gasoline model fuels containing each of these three olefins are used to support this research. Results prove these three olefins exhibit comparable effects on engine combustion and regulated emissions. However, their differences in affecting VOC and particulate matter emissions are of great significance. DIB leads to higher ethane emission while 1-hexene results in remarkably lower acetylene emission. 1-pentene generally leads to lower formaldehyde and acetaldehyde emissions. Nevertheless, these three olefins lead to comparable total VOC emissions. Further analyses show that alkane, olefin and aromatics take the most part of VOCs while olefin in emission take the most responsibility of ozone formation potential. Although 1-pentene in gasoline does not lead to the lowest VOC emissions, it results in the lowest OFP value when compared with DIB and 1-hexene. Such a finding signifies that gasoline with more 1pentene content help to alleviate emission photochemical effect when compared with olefin content DIB or 1hexene, which hints that gasoline with C5 olefin might be favorable than C6 olefin content when OFP of engine VOC emission is considered.