Full-scale experimental study on water mist fire suppression in a railway tunnel rescue station: Temperature distribution characteristics

• Published in: Process safety and environmental protection 2021-02, Vol.146, p.396-411
• Main Authors: Fan, Chuangang, Bu, Rongwei, Xie, Xiaoqing, Zhou, Yang
• Format: Article
• Language: English
• Subjects: Cooling effects; Longitudinal ventilation; Mist; Railroads; Railway stations; Railway tunnels; Rescue station; Smoke; Temperature control; Temperature distribution; Tunnels; Ventilation; Visibility; Water mist parameter; Wind speed
• ISSN: 0957-5820; 1744-3598
• DOI: 10.1016/j.psep.2020.09.019

To ensure the safe evacuation of personnel in railway tunnel rescue stations, smoke temperature characteristics on both the platform and train sides with different longitudinal wind speeds and water mist parameters such as water mist activation time, working pressure, discharge coefficient have been investigated in detail in this study. [Display omitted] Rescue stations are essential for emergency evacuation in super-long railway tunnels. However, the deficiency of related studies aiming at improving the fire suppression performance of water mist system in fire scenarios limits its application significantly. In this work, 20 sets of full-scale water mist fire suppression experiments were conducted to examine the impacts of water mist system on smoke temperature characteristics, including water mist activation time (denoted by t), working pressure (P), k-factor (K) and longitudinal wind speed. Results show that when t = 3 min, P = 12 MPa, and K = 0.5, the best performance of temperature control could be achieved. Although there are violent temperature fluctuations in the train side, the smoke temperature could be easily restrained. Moreover, it is found that longitudinal ventilation is helpful to improve the visibility at platform and reduce smoke temperature. When P = 12 MPa, the coupling effect of water mist and longitudinal ventilation on cooling smoke is better. In addition, the non-dimensional maximum temperature rise is found to show a great cubical dependency on vertical height, and decreases along with a larger longitudinal distance for all cases. Also, under longitudinal ventilation, the non-dimensional maximum temperature rises are lower than that without longitudinal ventilation in the coverage area of water mist. Results of this work can provide a significant reference for the design of water mist system in railway tunnel rescue stations.