Emissions and Fuel Economy of a Stratified Charge Engine Operating on a Gasoline/Methanol Blend,

摘要

Emissions and fuel economy of a large volume prechamber,fuel injected,stratified charge engine with gasoline and a gasoline/20% methanol blend have been measured. The engine is a modified CFR cetane test engine operating with MBT spark timing and 8.4:1compression ratio. The effect of both prechamber and main chamber mixture ratio on engine operation and emissions was investigated in some detail. Lowest overall emissions were achieved simultaneously with low fuel consumption at a prechamber equivalence ratio of 1.10. An improvement over the conventional engine in the area of NO emissions was found but it is obtained with an increase in CO and HC emissions. The gasoline/methanol blend shows significant improvement over gasoline in NO emissions but also with higher exhaust CO. Fuel economy was not significantly different for the two fuels so long as the prechamber was not overly rich.