地铁车厢污染物分层稀释系统及病毒传染模型改进

Stratified Dilution System for Pollutants in Subway Carriages and Improved Virus Infection Prediction Model

传统地铁车厢的全混合通风模式存在气流交叉污染现象,为改善后疫情时期地铁车厢空气品质,对宁波轨道交通二号线车厢的污染物浓度进行了测试,发现早晚高峰时期车厢内CO_(2)超出健康标准,并在沿车厢高度方向存在2个污染物峰值。以此为背景,提出了车厢分层通风技术来改善污染分层现象,采用计算流体力学方法对比了传统车厢与分层通风车厢的流场特性和污染物扩散轨迹,指出分层通风车厢可以在车厢中部形成空气幕,有效改善坐姿乘客呼吸区的空气品质;并改进了Wells-Riley感染预测模型的方程,增加了污染物浓度作为变量,实现对密闭空间任意污染物浓度下的致病感染概率预测。研究表明:双人模式时,分层通风车厢相比传统车厢,将坐姿人群的病毒感染概率从25.4%降低至3.07%。

The full-mix ventilation mode of traditional subway cars has cross-contamination of airflow. In order to improve the air quality of subway cars in the post-epidemic period, the pollutant concentration in the cars of Ningbo Rail Transit Line 2 was tested, and it was found that the CO_(2)in the cars exceeded the health standard during the morning and evening rush hours. And there are two pollutant peaks along the height of the carriage. According to this background, a layered ventilation method was proposed to improve the pollution layering phenomenon. Computational fluid dynamics method is used to compare the flow field characteristics and pollutant diffusion trajectory between the traditional carriage and the stratified ventilation carriage. The research results indicate that stratified ventilated carriages can form an air curtain in the middle of the carriage, effectively improving the air quality in the breathing area of seated passengers. The research also improved the equation of the Wells-Riley infection prediction model and added the pollutant concentration as a variable to realize the prediction of the infection probability under different pollutant concentration in the space. Studies have shown that stratified ventilated carriages reduce the probability of virus infection in sitting people from 25.4% to 3.07% compared to traditional carriages under the two-person mode.