Investigation of the performance of lateral ventilation in subway station fires

Lateral ventilation has been widely used in tunnel ventilation in recent years. But the effect of lateral ventilation in subway stations has received little attention and discussion. Based on numerical simulation, a real standard subway station is modelled in this paper to study the applicability of lateral ventilation in subway stations. Both the traditional ventilation system with vents located at the bottom of ventilation ducts and the proposed lateral ventilation system with vents located at the side of ventilation ducts are presented and compared. Parameters including temperature, CO concentration, and smoke layer height are adopted to qualitatively study the smoke control effect of different vent layouts. Parameters including ventilation efficiency and fractional effective dose are adopted to quantitatively model the ventilation performance of different vent layouts. The results indicate that: (1) The side vent layout is recommended in subway station emergency ventilation with slower horizontal smoke diffusion, slower vertical smoke settlement, and better smoke layer stability. (2) The advantage of side vent layout is quantitatively validated with higher ventilation efficiency in every vent and lower gas toxicity at eye-sight height. (3) Sensitivity analysis of fire location, heat release rate, vent amount, and vent size are conducted to verify the advantage of the side vent layout. In all scenario groups simulated, a better smoke control performance, higher ventilation efficiency, and lower fractional effective dose value is acquired in side vent layout. This research presents the application prospect and design method of lateral ventilation in subway stations.