Abstract
| - A spark ignition engine is used to determine the influenceof fuel composition and air/fuel equivalence ratio onthe exhaust emissions of regulated pollutants. Two specificfuel matrices are used: the first contains eight hydrocarbonsand the second contains four oxygenated compounds.A specific experimental design is used for these tests. Fuelaromatics increase the exhaust CO, HC, and NOx atstoichiometry, lean and rich conditions. Lambda is moreimportant than fuel composition in the case of CO and HC.At stoichiometry, the addition of oxygenated compoundscan decrease exhaust CO, HC, and NOx up to 30%, 50%,and 60%, respectively. Under these conditions, theaddition of 5% of 2-propanol is the most effective for thereduction of CO, the addition of 20% of ethanol for the reductionof HC, and this of 5% of methyl tributyl ester (MTBE) forthe NOx. The addition of oxygenated compounds can decreaseCO by 30% at lean conditions, while no decrease isobserved at rich ones; HC and NOx can decrease up to30% and 80%, respectively, under lean conditions and 50%under rich ones. At all lambda tested, exhaust NOxincreases with the addition of 20% of 2-propanol.
|