This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Spark Ignition Engine Hydrocarbon Emissions-The Effects of Cyclic Dispersion and Fuel Into Oil Solubility
Published January 01, 1991 by Institution of Mechanical Engineers in United Kingdom
Event: AutoTech 91
Both cyclic dispersion and fuel into oil solubility are known to be significant contributors to hydrocarbon emissions from spark ignition engines. In an attempt to further assess their particular effects, a fast acting sampling valve has been applied to the exhaust port and combustion chamber of an engine running on chemically defined fuels under conditions designed to highlight both the above phenomenae.
Under very lean conditions, the effect of cyclic dispersion is known to have particular relevance to emissions from spark ignition engines. Running the engine in this region, samples were taken at preset crank angles from cycles with specific peak pressures. The samples taken were then partially resolved into hydrocarbon species groups. The results of this analysis were then partially resolved into hydrocarbon species groups. The results of this analysis are presented, together with an overview of their relative contribution to tailpipe emissions.
A second study program was directed towards study of the oil absorption/desorption effect. The engine was run on fuels of widely differing solubility, and the effect of this on the levels of hydrocarbons found within the combustion chamber observed. After allowing for the influence of other relevant factors, lower fuel solubility caused a significant reduction in the amount of unburnt hydrocarbons, and this could be ascribed to the effect of fuel into oil absorption/desorption.