Numerical Research Of Subway Piston Wind And New Metro Psd Environmental Control System

The expense of the construction and operation of subway is immunse, and the ECS is one of the most expensive parts, only second to the traction of the subway. One of the most essential issue to be considered in the subway construction, therefore, is to choose a proper ECS.Generally speaking, ECS can be a safety door system or a platform screen door(PSD) system. For the latter, screen doors are arranged along the platform in order to separate the railway track and the waiting passengers. This system has the advantages of safety, cleanliness, and energy-conservation during summer and winter when air-conditioner is needed. But during other times, the piston-wind-effect cannot be fully used in the platform with PSD system; but in the safety door system, the railway is next to the waiting area without any separation. Therefore, the piston wind, on the one hand, contributes to the ventilation and air-cooling. However, on the other hand, a large quantity of cold air blows to the channel during winter, which weakens the heating effect of air conditioners, and causes larger energy consumption.Combining the advantages of the two systems mentioned above, a new PSD system with controllable air ports is to be developed. This system is a combination of PSD and safety door system. During summer and winter when air conditioners are used, the air ports on the PSD will be closed, and at other times opened. In this method, energy can be saved all the year round.In this paper, dynamic mesh technology is applied to the research of the properties of the piston, and the cause of the piston wind and other influencing factors are analysed. Additionally, based on the study of Sanshanjie subway station in Nanjing, this paper proves that the model and the calculation of CFD is correct; on the basis of CFD technology, this study simulated four situations:single train arriving and departuring, two trains arriving and departuring, and analysed the varying pattern of piston wind and its influence on the air quality and ventilation of the platform. The simulation suggests that when the air ports opened, the air quality is acceptable to the passengers and the air circulation ratio can meet the requirement of five times per hour.This paper provides a theoretical foundation for the application of the PSD with controllable air ports.