Influences of the optimized air curtain at subway entrance to reduce the ingress of outdoor airborne particles

It is of great significance to control the air quality of underground metro stations, especially considering their poorly ventilated environments. Existing literature mainly focuses on the removal and control of underground pollutants and seldom pay attention to the ingress effects of atmospheric pollutants (e.g., from the burning of fossil fuels, exhaust gas of vehicles, etc.) diffusion through the entrances/exits. In this study, we aim to study the reducing effects of integrated air curtain and exhaust systems on atmospheric airborne particles entering into the metro stations. Validated turbulent models were adopted for numerical simulations. The associated effects of air curtain velocity, exhaust velocity, and atmospheric wind speed were investigated. Four different installation locations of the air curtain were considered. Subsequently, monitoring, Artificial Neural Network, and air purification methods were proposed for the optimal design of integrated air curtain and exhaust system. It is concluded that an integrated air curtain and exhaust system can improve the interception efficiency on particles around 40% compared with no measure taken at the subway entrance, or it can be increased about 20% compared with only using an air curtain system (no exhaust vent) at the entrance.