| With the wide application of the Platform Screen Door system(PSD)in metro station,the accompanying energy saving requirements are becoming more and more significant.Reasonable use of the unorganized ventilation of entrance/exit passages(EEPs)can effectively improve the air quality in the metro station.It also can replace the mechanical fresh air system or reduce the mechanical fresh air load in summer,so as to achieve the goal of energy saving.At present,there is a lack of understanding of the unorganized ventilation of EEPs when people design.It's can't be reasonably used nether in design nor in operating of ventilation and air conditioning.Therefore,it is necessary to analyze the characteristics and influencing factors of the unorganized ventilation of EEPs,and the effectiveness of using the infiltration fresh air to replace the mechanical fresh air system,which is studied to achieve energy conservation goals.Taking a typical island metro station public in Chongqing as the research object,this paper carried out the following research work on the characteristics of the unorganized ventilation of EEPs:The one-dimensional ventilation network model of the metro station was established,the resistance coefficient and impedance of each branch were calculated,and the air leakage of PSD was calculated according to the series-parallel relationship of each branches in network model.The results was used as the boundary condition of three dimensional numerical simulation of the unorganized ventilation of EEPs in metro station.The three-dimensional physical model and numerical model of metro station were established,and the numerical simulation of the unorganized ventilation of EEPs under the negative pressure effect was carried out.It was proposed a reasonable simplification method for EEPs,which the number of EEPs,the number of bends and the size of the area in a reasonable range.The transient simulation of the unorganized ventilation of EEPs when PSD is opened was carried out and the influencing factors were analyzed.The results show that the unorganized ventilation of EEPs are stable after 15s.The increase in the number of EEPs firstly leads to the increase in the volume of the unorganized ventilation of EEPs,followed by a brief rise in the station hall temperature.However,the change of the number of EEPs does not affect the platform temperature.The change in the number of EEPs bends only affects the unorganized ventilation in a single EEP.If the number of EEPs bends increases by one,leads to the unorganized ventilation of EEPs decreases by 0.2m~3/s.The area changing has an impact on the unorganized ventilation in all EEPs.Every one meter increase in the width leads to a increase of the unorganized ventilation at present EEP,while other EEPs volume decreases by5%.In the meanwhile,the total volume of ventilation will increase by 0.2m~3/s.A reasonable setting method of the internal circulation mode of the metro station environmental control system is proposed.Through the steady simulation of the carbon dioxide concentration distribution in the public area of metor station under different passenger flows,the effectiveness of using the infiltration fresh air to replace the mechanical fresh air system in the recent and forward term working conditions was studied.The results show that when adopts the internal circulation mode,the unorganized ventilation of EEPs can meet the fresh air demand under the recent working conditions,and the carbon dioxide concentration is below 1000ppm either in station hall or platform.However,the carbon dioxide concentration in the platform will exceed standard when the passenger flow reaches the level of forward term super-peak passenger flow,even if the total volume of the unorganized ventilation of EEPs is 3.2 times more than the demand for fresh air.It is necessary to open the mechanical fresh air system when the passenger flow out of limited. |
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