China Safety Science Journal ›› 2020, Vol. 30 ›› Issue (8): 143-150.doi: 10.16265/j.cnki.issn1003-3033.2020.08.021

• Public safety • Previous Articles     Next Articles

Research on extinguishing characteristics of liquid nitrogen in urban underground utility tunnel

LI Huaxiang1,2, ZHANG Guowei1,2, JIA Boyan3, ZHU Guoqing1,2, GUO Dong1,2, ZHANG Peng3   

  1. 1 Key Laboratory of Urban Underground Fire Protection of Jiangsu Province, China University of Mining and Technology, Xuzhou Jiangsu 221116, China;
    2 Institute of Public Safety and Fire Engineering, China University of Mining and Technology, Xuzhou Jiangsu 221116, China;
    3 State Grid Hebei Electric Power Research Institute, Shijiazhuang Hebei 050011, China
  • Received:2020-05-06 Revised:2020-07-07 Online:2020-08-28 Published:2021-07-15

Abstract: In order to study feasibility and effectiveness of LN2 in suppressing fire in urban utility tunnels, experiments on its fire extinguishing characteristics were carried out, and its fire control efficiency and influencing factors were studies by changing injection parameters, such as direction of LN2 nozzle and release distance. The results show that LN2 can quickly extinguish a utility tunnel fire. Its rapid extinguishing mechanism is a result of coupling effect of cooling and inerting. After being injected into utility tunnel, LN2 evaporates abruptly, forming a low temperature nitrogen cloud which rapidly cools gas. Meanwhile, as cloud spreads, pyrolysis gas is inerted, isolating fire from oxygen and finally extinguishing it. In addition, it is found that horizontal nitrogen injection has better fire extinguishing effect overall than vertical downward injection, and fire extinguishing time increases with the increase of longitudinal distance between nozzle and fire source.

Key words: underground fire, utility tunnel, liquid nitrogen, fire extinguishing experiment, inert

CLC Number: