Network Simulation and Scale-Model Experimental Study of Natural Ventilation in Subway Stations

Abstract

Thermal comfort in subway stations is usually satisfied by mechanical ventilation and an air conditioning system. However, in practice, natural ventilation exists in underground subway stations, which is driven by wind pressure, buoyancy pressure, or negative pressure caused by piston effect. It is of high significance to improve the design of an environment control system and conserve operational energy by correctly predicting the natural ventilation of the subway station with whole-sealed platform screen doors. Several subway stations in China have been tested in different seasons and different operational conditions from 2015 to 2016. The tests included the temperature, humidity, and CO2 concentration of the outdoors and the subway stations. The distribution and the change of CO2 concentration in the station hall floor and the platform floor were also tested and compared in the case of opening and closing the mechanical fresh air supply system. The conclusion that natural ventilation could provide adequate outdoor fresh air supply was drawn. The numerical study of the natural ventilation potential and thermal environment of a public area under different scenarios were performed by a network model-based program. The most optimized and energy-efficient operation and control strategies under different weather conditions of Shapingba subway station can be obtained based on simulations. In the end, the influence on natural ventilation, such as wind speed and direction, negative pressure caused by piston effect, and track exhaust during the train dwells, buried depth, heat load, and the number of ground entrances in a subway station were analyzed as well.