The Verification of Vehicle Emission Models with the Gaussian Dispersion Model and CFD Model

• Main Authors: Wei-Cheng Chen, 陳威成
• Other Authors: 盧昭暉
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/32291644753367398621

碩士 === 國立中興大學 === 機械工程學系所 === 94 === This paper is composed of two parts. The first part adopts the roadside concentrations comparison method to verify the vehicle emission model. The pollutant dispersion model Caline 4 was used to evaluate the validity of the vehicle emission factors. The measured roadside air quality data obtained from Datong Monitoring Station were first used for comparison. Results of comparison showed that the predicted data and the measured data varied consistently. Measured data at another 11 sites were then used for comparison. The data at Guilin Rd. were fairly good for motorcycle test. The data at Bagua Mt. tunnel matched well with automobile’s emission factors. The data obtained at Kaoshung harbor were consistent with the Diesel vehicle’s emission factors. The second part is a comparison of pollutant dispersion calculation using CFD tool with that obtained with Gaussian model. Three cases were studied in this paper. The first case is a point source dispersion, which is used to simulate stationary vehicles waiting in front of red light. The second case is a line source with finite length, which is used to simulate vehicles in motion. The third case is a confined line source, which is used to simulate vehicles moving in streets with high rise buildings in both sides. The commercial CFD code Fluent was used in this paper to carry out calculations. Results of calculations showed that in the case of point source, the maximum concentration occurred on the ground surface of about 9 ppm as the source strength is 0.25g/s. The transverse dispersion distance is about 6 m at the location downstream of 30 m. In an open area, the concentration on the ground surface at 30 m downstream is about 0.3 ppm as the source strength is 0.0011 g/m-s. A real case in kaoshung Siaokang Rd. was studied in this paper. The CO concentration was estimated to be 0.93 ppm according to the measured wind speed and the traffic flow.