The Effect of Automotive Operating Conditions on Polynuclear Aromatic Hydrocarbon Emissions

Abstract

The effect of operating conditions of automobiles on polynuclear aromatic hydrocarbon (PAH) emissions was studied. The PAH emission rate for a car with a high engine oil consumption rate increased with an increase in the car speed. However, the change of the emission rate was not so noticeable for a car with a low oil consumption rate.
In the 10-mode city driving cycle, PAH emission rates, on a concentration basis, were highest during 40 km/h cruise, and on a mass basis were highest during accelerations. The lowest emissions were during idling.
The high PAH emissions for the operating conditions of high speeds and accelarations were mainly caused by the high oil consumption due to high engine speeds and by the increase in the rate of formation of PAH from consumed oil with the increase in the pyrolysis temperature of the oil.
No obvious change of PAH emissions with load condition under a steady speed of 40 km/h was observed.