Thermal Environment And Control Strategy Of Subway Station In Winter In Northern China

With the acceleration of economic development and social progress and urbanization process,more and more large and medium-sized cities are facing traffic pressure.In order to alleviate the traffic pressure,subway construction has been favored by more and more Chinese cities.In recent decades,China’s subway project has been developed.At present,more than 30 cities have opened subways,and more than 50 cities in China have planned to build subways.With the blowout construction of the subway in China,the construction sites have been gradually shifted from the southern cities to the north.Especially since the northern cities in the severe cold regions like Harbin,Shenyang,Changchun,Urumqi and other cities began to build subway.In these regions,the winter is cold and long,and the average temperature in the coldest month is lower than-10?C.Since the temperature of the station is too low in winter,which not only makes passengers and station staff feel uncomfortable,but also causes some valves and pipes to freeze.Therefore,thermal environment of the subway station in the cold region of north China has received more and more attention,with to be further studied and solved.In this paper,field measurements of the thermal environment and the piston wind effect of the station in Xi’an metro line 2 and Lanzhou metro line 1 in winter were conducted to get first-hand detailed data.Taking Xi’an metro line 2 as the example,the entire subway lines model was established based on IDA tunnel,then the station thermal environment and the piston wind effect was analyzed.Based on the climatic conditions of the major subway cities in northern China,the main influencing factors of the thermal environment of the subway stations in winter are analyzed using the orthogonal experiment.According to local annual average temperature（the temperature of the soil thermostatic layer）and the outdoor ventilation temperature in winter（the coldest monthly mean temperature）,the thermal environment control of typical cities in northern China in winter is divided into three regions:I region T_siol>12?C,T_wv>-3.6?C;II region 9?C≤T_siol<12?C,T_wv>-7.9?C;III region T_siol<9?C,T_wv<-7.9?C.Based on the typical single-hole single-lane driving mode,the correlation formula of piston wind velocity in the periodic driving mode is proposed.In view of the typical double-deck island station,the influence of piston wind on the subway station is studied,revealing the influence and characteristics of piston wind with different the train cycles,platform door opening,piston wind valve opening and circuitous wind path settings.Through the significance analysis of the factors,the correlations of the station entrance and exit channel,the inlet air volume of platform gate and the running cycle,the platform gate opening,the detour air channel setting and the piston air valve opening are put forward.Finally,an unorganized air supply control device installed in the gateway is proposed.A waste heat utilization system and some measures and key technologies of improving thermal environment in winter at the station are put forward.In addition,typical cities in area II and III are selected to analyze the winter thermal environment of subway stations in the early,near and long-term operation,and the overall operation scheme of the environmental control system in winter are provided,which can be used as reference for the operation of subway projects in north China.