Simulation Of Pollutant Concentration Distribution Characteristics And Safety Assurance In Subway

With the development of urbanization in our country,subway seats are an efficient and green mode of transportation.While providing citizens with a fast way to travel,they are also responsible for the safety and comfort of passengers.Therefore,it becomes very important to improve the air quality and thermal comfort of human body in the carriage.Using fluid simulation technology to simulate the airflow organization in the carriage can obtain quantitative results close to reality,which can provide more meaningful reference value in solving practical engineering problems.In this paper,taking ALSTOM's AC03 electric subway train carriage as an example,the concentration distribution and safety guarantee of pollutants in subway carriages in southern China were studied.Based on the measured data and questionnaires,this paper found that more passengers think that the air circulation in the center of the car is higher and the temperature in the center of the car is lower.Taking the subway in summer,the overall feeling in the car is cold.The air circulation in the car causes discomfort to the human body.37% of passengers think that the thermal environment in the car is uncomfortable.21% of passengers do not know the location of escape tools in subway cars.In summer,the temperature of the compartment is lower than the standard value,the humidity exceeds the standard value,and the wind speed is within the standard value range.However,low wind speed will lead to low air circulation rate and carbon dioxide concentration in the compartment exceeds the standard value.On the basis of actual measurement and questionnaire,CFD numerical simulation is used to discuss and study the subway temperature,velocity,wind speed and carbon dioxide concentration.It is shown that in southern summer subway carriages,the air supply velocity of 3.0m/s and the air supply angle of 90 are the most easy to control the temperature of the carriages.It is helpful to dilute the CO2 caused by passengers' breathing and the temperature changes caused by the virus and passengers' breathing,reduce the thermal pollution,improve the air quality of the carriages and the comfort of passengers,and reduce the probability of virus transmission.This paper further puts forward optimization suggestions and uses CFD numerical simulation to verify them again.It is found that the air supply mode of upper air supply and lower air supply is more conducive to improving the vertical air flow rate in the carriage.According to the numerical simulation under the optimized scheme,it is verified that the upper and lower air supply modes are easier to control the compartment temperature when the compartment air supply speed is 3.0m/s than the upper and lower air supply modes.