| With the rapid development of China's economics and the accelerated process of Urbanization,urban rail transit is also in the process of rapid development as an efficient and convenient mean of transportation,the whole-sealed platform screen door have become increasingly popular in transit station.Plenty of outdoor fresh air will flow into an out the subway station through ground entrances under the synthetic effect of wind pressure,thermal pressure,and negative pressure by the formation of piston effect and track exhaust during the train dwells.While the design of environment control systems and operation of equipment in subway stations lack of the understanding of the natural ventilation of underground station,not take into account the effect of outdoor fresh air flow into and out the subway station.So the designer must be able to predict the effect on the subway station ventilation and air conditioning heat load,by accurate estimating the fresh air volume flow into and out the subway station through ground entrances,to achieve the purpose of more reasonable and energy-saving design of environment control systems and operation of equipment.Because of the complicated natural ventilation process and variable influence factors,the international researches on this field are not in-depth or comprehensive so far.First several subway stations in Chongqing and Chengdu have been tested in different seasons and different working conditions during the period from 2015 to 2016.The main contents of the tests included the ventilation condition and the temperature and humidity of ground entrances,the temperature and humidity and CO2 concentration of outdoors and the subway station.The distribution and the change of CO2 concentration of the station hall layer and the platform layer were also tested in the case of opening and closing mechanical fresh air system.The existing scale of natural ventilation and thermal environment condition in subway station were obtained by testing.The existing fresh air volume flow into and out the subway station was about ten times the amount of maximum number of fresh air demand in the station.So it can completely met the demand for fresh air volume.Then,a computer program has been complied using Matlab software according to network model,a subway station model test bed has been also built,to carry out the thermal environment and fresh air volume numerical simulation analysis of subway station.The feasibility and reliability of network model numerical simulation method to study the influence of natural ventilation in subway station is verified by comparing with the field measured dates and test dates from subway station model test bed.Next,according to the principle of the temperature of subway station is less than design criterion(29?),and full use of natural ventilation,use as little ventilation and air conditioning facilities,used the network model computer program to carry out the natural ventilation potential and public area thermal environment numerical simulation analysis of subway station under different conditions.The most effective energy saving operation control mode and transition condition of Shapingba subway station can be found through the trial calculated results which can determine the most effective energy saving operation control mode under different conditions and its applicable critical meteorological condition.Finally,every factor that may influence the final results: the wind speed and direction,the negative pressure by the formation of piston effect and track exhaust during the train dwells,the buried depth of subway station,thermal load of subway station,the number of ground entrances,the number of elbow in ground entrances,the area of ground entrances were analyzed separately,in order to further reveal the extent of the impact of some factors on subway station natural ventilation effectiveness.The conclusion can provide reference for the design of subway station structure. |
PDF Full Text Request