Speed‐dependent emission of air pollutants from gasoline‐powered passenger cars

Abstract

In Korea emissions from motor vehicles are a major source of air pollution in metropolitan cities, and in Seoul a large proportion of the vehicle fleet is made up of gasoline-powered passenger cars. The carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx) and carbon dioxide (CO2) contained in the exhaust emissions from 76 gasoline-powered passenger cars equipped with three-way catalysts has been assessed by vehicle speed, vehicle mileage and model year. The results show that CO, HC, NOx and CO2 emissions remained almost unchanged at higher speeds but decreased rapidly at lower speeds. While a reduction in CO, HC and NOx emissions was noticeable in vehicles of recent manufacture and lower mileage, CO2 emissions were found to be insensitive to vehicle mileage, but strongly dependent on gross vehicle weight. Lower emissions from more recent gasoline-powered vehicles arose mainly from improvements in three-way catalytic converter technology following strengthened emission regulations. The correlation between CO2 emission and fuel consumption has been investigated with a view to establishing national CO2 emission standards for Korea.

A Review on the Characteristics of Air Pollutants Emitted from Passenger Cars in Korea

“…CO, HC, NOx, CO 2 and PM have similarly been shown to be dependent on speed regardless of fuel type according to previous studies (2,34,15) . Giannelli et al (2002) (13) reported that low speed (16.1-24.1 km/h) emissions of CO, HC and NOx increased by 15-40%, 20-80% and 20-50% for gasoline vehicles, respectively, compared with those at higher speeds (24.1-104.6 km/h).…”

“…Giannelli et al (2002) (13) reported that low speed (16.1-24.1 km/h) emissions of CO, HC and NOx increased by 15-40%, 20-80% and 20-50% for gasoline vehicles, respectively, compared with those at higher speeds (24.1-104.6 km/h). The CO, NOx, HC and CO 2 emissions at lower speeds (4.7-10.8 km/h) decreased rapidly with increase in speed while they remained unchanged at higher speeds from 65.4 to 97.3 km/h for gasoline passenger cars (2,35) . Also, CO, HC, NOx and PM emissions from diesel vehicles decreased at lower speeds (4.5-10.5 km/h) rather than higher speeds (65.4-97.3 km/h) (34) .…”

“…The vehicle mileage associated with model year because model year was older as the mileage accumulates. According to previous studies, it was found that for CO, HC, and NOx, the cars of each mileage were over 80,000 km emitted 44-78%, 53-86%, and 72-81% more than those with mileage under 80,000 km, respectively (2) . Ntziachristos and Samaras (2000) (14) noted that CO, NOx and HC emissions at ≤ 10,000 km, mileage class decreased 63-66% rather than those at > 90,000 km, mileage class.…”

“…Moreover, most of the road vehicles are concentrated in metropolitan cities. Consequently air quality has deteriorated in metropolitan areas and air pollution has now become a national concern (2) . As of 2011, on-road vehicles in Seoul were believed to be the single largest source for the major atmospheric pollutants, contributing, 81% of the carbon monoxide (CO), 51% of the fine particulate matter (PM 2.5 ), and 45% of the nitrogen oxides (NOx) to the Korean national emission inventory (3) .…”

Assessment of technologies to reduce fuel consumption and pollutant emissions of modern passenger cars in real - world driving conditions

“…This could be attributed to engine and exhaust aftertreatment degradation resulted from the high mileage of the vehicles. According to Jung et al this is a root cause for higher emissions under all operating conditions (at both high and low loads) [124].…”