Speciated Hydrocarbon Emissions and the Associated Local Ozone Production from an Automotive Gasoline Engine

Speciated Hydrocarbon Emissions and the Associated Local Ozone Production from an Automotive Gasoline Engine

Journal:

International Journal Engine Research, Vol. 5, No. 1, pp. 53-70
JER 03503, 2004

Authors:

S V Bohac and D N Assanis
Mechanical Engineering, University of Michigan
H L S Holmes
Department of Chemistry, Eastern Michigan University

Abstract:

Concentrations of total and individual exhaust gas hydrocarbon species were measured from a contempor- ary automotive gasoline engine to gain insight into how an engine's operating conditions affect the combustion and post-flame oxidation processes and to estimate the ozone- forming potential of these hydrocarbons. Both the custom- ary method of estimating maximum ozone production using maximum incremental reactivity (MIR) factors and a new method of estimating actual local ozone production (LOP) were used to quantify the harmfulness of the exhaust hydrocarbons. Depending on local atmospheric conditions, LOP estimations are about 2± 10 times less than the method of maximum ozone production using MIR factors. Per unit of engine output, retarded spark timing and higher engine load reduce the LOP of catalyst-in hydrocarbons, while the air± fuel ratio does not strongly affect the LOP of catalyst-in hydrocarbons. LOP is increased during a start-up and drastically decreas ed by the catalytic converter, once the catalyst is heated to its operating temperature and the engine is run at stoichiometry.

Paper: P2004_04.PDF