Hydrocarbon Oxidation in the Exhaust Port of a Spark Ignition Engine

An experimental study was performed to determine the fraction of unburned hydrocarbon emissions which are oxidized in the exhaust port of a spark ignition engine. The technique used was injection of a CO//2 quench gas into the exhaust port, at various planes along the port centerline, to cool the exhaust gas and "freeze" the hydrocarbon oxidation reactions. By quenching the reaction of hydrocarbons at the cylinder exit plane, cylinder exit hydrocarbon emissions levels were determined. By differencing the concentration of hydrocarbons observed during quenching and nonquenching operation, the fraction of hydrocarbons reacting in each section of the exhaust was determined. Experiments were carried out to define the effects of engine operating conditions on the fraction of hydrocarbons oxidized.