Evaluating the performance of air quality models for roadside traffic exhaust dispersion is critical to sustainable environmental development and urban pollution management. This study introduces three models, namely CAL3QHC, ENVI-met and ANSYS Fluent, to model the pollutant dispersion at an isolated busy urban signalized intersection, by taking fine particulate matter (PM_2.5) as the subject matter. A dynamic emission factor model was established based on Cell Transmission Model (CTM) and Portable Emission Measurement System (PEMS) experiment, which was further implemented with the User Defined Function (UDF) of ANSYS Fluent. Results from an empirical study based on the Jianchuan and Humin Road intersection, in suburb Shanghai, demonstrate that ANSYS Fluent performs better for PM_2.5 concentration prediction with carefully calibrated parameter settings. Simulation results from both CAL3QHC and ANSYS Fluent are within an acceptable scale, while ENVI-met performs better in assessing the correlation relationships between PM concentrations and the intersectional and meteorological factors. The concentration of PM_2.5 was found to increase significantly during the idle phase, which tends to be accumulated in front of the intersection buildings simultaneously. With the increasing of the altitude, the overall average PM_2.5 concentration of the intersection decreases gradually. Street canyons with high buildings were found with comparable lower wind speeds, hindering the pollutant diffusion. Finds of this study may assist urban intersection design from a variety of perspectives, e.g., lane channelization, signal timing, and even architecture styles of the surrounding buildings.

评估路边交通废气扩散的空气质量模型的性能对于可持续环境发展和城市污染管理至关重要。本研究引入CAL3QHC、ENVI-met和ANSYS Fluent三个模型，以细颗粒物（PM _2.5）为研究对象，对孤立繁忙的城市信号交叉口的污染物扩散进行建模。基于单元传输模型（CTM）和便携式排放测量系统（PEMS）实验建立了动态​​排放因子模型，并结合ANSYS Fluent的用户定义函数（UDF）进一步实现。基于上海市郊区剑川路和沪民路交叉口的实证研究结果表明，ANSYS Fluent 对 PM _{2.5 的}性能更好使用仔细校准的参数设置进行浓度预测。CAL3QHC 和 ANSYS Fluent 的模拟结果都在可接受的范围内，而 ENVI-met 在评估 PM 浓度与交叉和气象因素之间的相关关系方面表现更好。发现PM _2.5的浓度在空闲阶段显着增加，并且趋于同时在交叉路口建筑物前积聚。随着海拔的升高，总体平均 PM _2.5交叉口的集中度逐渐降低。发现具有高建筑物的街道峡谷具有相当低的风速，阻碍了污染物的扩散。这项研究的发现可以从多种角度协助城市交叉口设计，例如车道通道化、信号时序，甚至周围建筑物的建筑风格。