Hirohiko Hoshi

Effects of gasoline composition on exhaust emissions and driveability

A study of the effects of changes in gasoline composition is one area to explore in our effort to reduce tailpipe emissions from vehicles. However, affects on vehicle performances should also be considered from the perspective of practical useage. In this paper, the influence of gasoline composition (aromatics), volatility, and MTBE blending on engine outlet and tailpipe emissions are discussed in particular, focusing on distillation properties which have a close relationship to driveability. Under stable driving conditions and without a catalitic converter, the effects of gasoline volatility is small, while aromatics in gasoline affect exhaust HC and NO{sub x} emissions. MTBE has a leaning effect on the engine intake air/fuel mixture. During a transient driving cycle, a high gasoline 50% distillation temperature causes poor driveability, as a result, HC emissions increase.

The influence of fuel qualities on white smoke emissions from light-duty diesel engine

In many countries, cetane number and distillation properties of diesel fuel have been changing, thus affecting the performance of diesel engines. This paper describes investigations made on the effect of diesel fuel quality on white smoke (one of the important emissions of diesel engines). The result of simple laboratory tests simulating high altitude conditions plus field tests using three types of diesel engines supplied with various types of diesel fuels is given. It was found that white smoke appearing tendency correlated best with cetane number and the 90 percent distillation point of the fuel. The field test performed at high altitude correlated well with the simple laboratory tests.