|
The purpose of this study was to explore components and concentrations of motorcycle emissions in Taiwan. The driving patterns of motorcycles in Taiwan were simulated in a dynamometer. Samples of emissions were taken under idling, acceleration, constant speed, and braking conditions. Total hydrocarbon (THC), carbon monoxide, and nitrogen oxides were analyzed with an automated instruments. Fifty-one volatile organic compounds (VOCs) were analyzed with gas chromatography. The effects of motor type (2 strokes or 4 strokes) and age on motorcycle VOC emission profile were assessed. Emission factors (EFs) were determined from emission concentrations; and ozone production potentials of the various VOCs were also obtained using maximum incremental reactivity (MIR) factors. The results showed that the emission concentrations of in-use motorcycles were much different from the newly produced motorcycles. The EFs of two- and four- stroke new motorcycles were 2.63, 3.28, 0.03 g/km and 6.68, 1.33, 0.52 g/km, for CO, THC, and NOx, respectively. For in-used motorcycles, the EFs of two- and four- strokes were 29.31, 18.18, 0.05 g/km, and 28.55, 2.48, and 0.33 g/km, for CO, THC, and NOx, respectively. Except for the NOx concentrations and EFs of four-stroke motorcycles, the concentrations and EFs of all other pollutants of in-used motorcycles were all higher than the new ones. Among different driving patterns, VOC concentrations were higher under idling, constant speed at 50km/hr, and braking conditions than under acceleration and constant speed at 30 km/hr conditions. For four-stroke motorcycles, VOC concentrations of in-used motorcycles were 17.1 times and 16.3 times of those of new motorcycles for idling and braking conditions, respectively; they were substantially different. The effects of total mileage, catalyst, and gasoline on motorcycle VOC emission profiles were also assessed. It showed that motorcycles using leaded gasoline had higher VOC concentrations and EFs. Moreover, comparing the concentrations and EFs of new and in-used motorcycles, the results showed that total mileage and catalyst usage.did play a role; however, other factors might also affect the results. The mean ozone production potentials of two- and four- stroke new motorcycles were about 2.86g/km and 0.73 g/ km, respectively, and those for two- and four- stroke in-used motorcycles were approximately 3.49 g/km and 2.94 g/km, respectively. It was obvious that the contribution of ozone production from 2-stoke motorcycles was higher than four-stroke ones. The mean ozone production potentials of new motorcycles was 1.80 g/km, while that of in-used ones was about 3.22 g/km. Thus, in-used motorcycles had higher potentials for ozone production.
|