Study On The Dynamic Thermal Environment And Operating Mode Of Ventilated Air Condition In Subway Station

Subway plays an important role in urban transportation system.Due to the relatively closed space,a large amount of heat generated in the operation process of subway needs to be eliminated through the thermal environment control system.Subway thermal environment and its control are very important to ensure the comfort of passengers,driving safety and service life of equipment,and also have a significant impact on the energy consumption of subway.With the rapid development of subway in large cities,the passenger flow increases dramatically,the train operation interval shortens,and the heat dissipation of vehicles(the main heat dissipation source)also increases,which makes the heat load of tunnels and stations significantly increase,affecting the normal operation of trains and the comfort of passengers.At the same time,it also increases the heat load of the environmental control system,especially in Beijing Metro Line 1 and line 2.Therefore,it is necessary to study the dynamic thermal environment of metro station and its control measures.In this paper,the typical station of Beijing Metro Line 1 is taken as the research object,and the method of theoretical analysis,field test,continuous monitoring and numerical simulation is used to study the dynamic change rule of thermal environment of the subway station equipped with air conditioning device and open environmental control system,as well as the operation mode of subway ventilation and air conditioning system.The main contents are as follows:(1)field test,continuous monitoring and thermal environment assessment of Metro thermal environment;(2)The dynamic thermal environment of Metro during the whole process of normal train running,deceleration entering,stopping and acceleration leaving the station;(3)Under the condition of natural ventilation and train movement,the regulation effect of ventilation and air conditioning system on the dynamic thermal environment of subway and the optimal operation mode.The results show that:(1)for the subway station with safety door and open door environmental control system,the temperature of indoor public area has a strong correlation with outdoor temperature,the strength of follow-up has a strong correlation with passenger flow,driving and other factors,and the thermal environment state parameters of the station show the unsteady time history and non-uniform spatial distribution;(2)The influence of train operation on the environment temperature and wind speed inside the station,including pedestrian passage,is greater than that of the main ventilation system;In the process of deceleration and stop,the temperature in the public area of the platform,especially the waiting area near the moving train,rises most obviously,and forms a large wind speed,which affects the comfort of passengers;(3)The working mode of ventilation and air conditioning system has obvious influence on the temperature distribution of platform and tunnel.The subway station adopts the air conditioning control scheme that the near track downward delivers the cold air and the upper part of the platform central return air,which can effectively restrain the temperature rise of the waiting area of passengers,but some of the cold air will be pumped into the exhaust air duct through the air duct on the rail top and sucked into the tunnel by the train wind,thus losing part of the cooling capacity;On the contrary,the air-conditioning flow is concentrated in the passenger flow area of the platform,the wind energy of the train entering and leaving the station can effectively improve the thermal environment of the public area of the platform,and the loss of cooling capacity is small;(4)The mechanical ventilation system of the station and the tunnel can be matched for operation.During the air conditioning season,the main mode of train operation is station exhaust and tunnel air supply;after the train stops,it is double exhaust mode.The research work of this paper is supported by the project of "Research on control scheme of overall thermal environment system of Beijing Metro Line 1 and line 2".The research results are of great significance for the scientific assessment of the thermal environment of metro,the optimization of thermal environment regulation,the improvement of environmental comfort and the improvement of the operation management level and service quality of Metro.