A detailed inventory was taken of evaporative emissions from parked gasoline vehicles in the Kanto region of Japan, 2015, based on the theoretical model to evaluate the amount of evaporative emissions. The inventory showed that evaporative emissions were high in metropolitan and urban areas because of the large populations in these areas and the high vehicle parking frequency. Using the new inventory, the sensitivity of evaporative emissions to the concentration of tropospheric ozone and secondary organic aerosol was evaluated using the chemical transport modeling solver, the community multiscale air quality modeling system (CMAQ), coupled with the weather research and forecasting (WRF) model. The calculation results showed that the evaporative emissions from permeation through fuel related parts were more significant in the generation of the tropospheric ozone than those from fuel tank venting. This was because the permeation emissions included a high proportion of high maximum incremental reactivity value components, such as aromatics. Neither of the evaporative emission types were significant secondary organic aerosol generators. Whole reduction of the evaporative emissions contributed an approximate 3 ppb decrease in tropospheric ozone in urban areas during the daytime. This information will contribute to the volatile organic compound (VOC) management strategy employed by governments worldwide.
Abstract. A portable emission measurement system (PEMS) was used to measure the real-world driving emissions pertaining to a Japanese middle-sized heavy-duty vehicle. The testing was performed with the vehicle being driven in the metropolitan area of Tokyo in four seasons (January, June, August, and November) to analyze the seasonal dependence of NOx and CO2 emissioans. The experimental results indicated that the amount of NOx emissions was particularly high in the cold season, owing to the slow starting of the NOx detoxification systems, that is, the exhaust gas recirculation and urea-selective-catalytic-reduction systems, under low ambient temperature conditions. In the real-world driving, a high acceleration pattern was observed in the low-speed region, which is not considered in the world harmonized vehicle cycle, which is the worldwide official driving mode in the chassis dynamometer experiment. Finally, the transient emission tables for NOx and CO2 were constructed based on the PEMS measurement results and the classical mechanic theory. The constructed tables well replicated the experimental results in all the considered conditions involving different ambient temperatures and locations. The proposed approach can be used to evaluate emission inventories in the future.
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