A study on longitudinal distribution of temperature rise and carbon monoxide concentration in tunnel fires with one opening portal

Abstract

The high temperature and CO concentration are the main factors leading to fatalities and injuries when a fire occurs in the tunnel. Based on the research results of smoke characteristics in tunnel fires, the longitudinal distribution of temperature rise and CO concentration in tunnel with one opening portal were theoretically analyzed and compared, and their longitudinal distribution as well as the variation law of their differences was obtained by using Fire Dynamics Simulator (FDS) for numerical simulation in one-dimensional horizontal diffusion stage. The results show that, without ventilation, the temperature rise decays as an exponential function, and the CO concentration decays as a power function, while the difference between them increases as an exponential function. The decrease in temperature rise and CO concentration is negatively correlated with the fire heat release rate, but the increase in the difference between the two is opposite. The result is in the same form as the longitudinal distribution laws at natural opening condition. The research conclusion will be helpful to the design of tunnel smoke prevention and exhaust engineering, as well as the management of evacuation and rescue.

Keywords

• Tunnel fire
• One opening portal
• Longitudinal distribution
• Smoke temperature
• Carbon monoxide concentration