Study On The Influence Of Air Leakage From Platform Screen Doors (PSDs) On Thermal Environment And Optimization Of Air Distribution In Subway Station

Environmental control technology plays an important role in the development of urban rail transit.Fully enclosed screen doors can effectively isolate passengers from the rail area,and are widely used for its economy,safety and comfort.However,under the combined action of piston effect,traffic density and indoor and outdoor environment,the air pressure and thermal ventilation generated by shield doors will affect the thermal environment of Metro stations.In the current Metro environmental control design,although the influence of shield door leakage on the station environment is taken into account,other factors and shield door leakage are not considered comprehensively.In this paper,through the field measurement,numerical simulation and orthogonal analysis of the subway thermal environment,the following main conclusions are obtained.Through the field test and analysis of a subway station in Xi'an,the temperature of the platform and station in winter varies with the outdoor temperature fluctuation(±2°C),and the average temperature of the platform is higher than the temperature of the station hall by about 4°C,which satisfies the winter ventilation conditions(the temperature of the platform should be higher than 10 °C).The measurement results of the paltform screen doors(PSDs)ventilation indicate that before the train enters the station,the wind speed at the entrance port begins to increase,and the speed reaches the maximum at 18~28s.When the train leaves the station,the wind speed through outbound-PSD increases rapidly,and the instantaneous speed can reach 7 ~8m/s.The ventilation volume through the inbound-PSD is greatly affected by the train moving in,and is less affected by the train moving out.Based on the numerical simulation of IDA Tunnel,this paper analyzes six main influencing factors affecting the thermal environment of subway station in winter.The primary factor and the degree of influence of each influencing factor were concluded,and the effect of PSDs air leakage on the station thermal environment is determined.With range analysis,the hall temperature is more sensitive to outdoor temperature.The influence degree of other parameters is soil temperature,number of open piston vent shafts,train interval,PSD opening area and passenger flow.While platform temperature is more sensitive to soil temperature,the impact degree of the six factors is ranked as soil temperature,outdoor temperature,number of open piston vent shafts,PSD opening area,train interval and passenger flow.In addition,the airflow distribution of the three ventilation schemes(mixed ventilation,displacement ventilation,wall-attached ventilation)was simulated.The results show that the wall-attached ventilation mode has a suitable speed and temperature distribution,which can provide a healthy and comfortable environment for the subway passengers.The ventilation scheme is optimized,and the airflow speed and temperature distribution of the occupant area under the attached mode are given.This study provides a reference for the energy-saving design and operation mode of subway environment control.