Analysis of distribution of toxic species of a fired train in ventilated tunnel

Abstract

A procedure is established and the distribution of products of a fired passenger train, (such as CO, and NOx) in a tunnel is simulated by fire dynamics simulator (FDS). Materials of a real train wagon are estimated and their fire products are calculated under both complete and incomplete combustion. A big urban railway tunnel with 4 lines in Tehran is considered and the effects of some parameters such as delay in emergency ventilation and tunnel separation wall on distribution of fire products are analyzed. Results show that delay in emergency ventilation causes to dispersion of fire products in tunnel and threats the passengers in an unsafe escape path at fire upstream after operation. The simulations show that the maximum time for rescue of passengers due to the fired train in tunnel is about 430 sec which is limited with accumulation of HCN as a first pollutant over critical health value. It is shown that the presence of separation wall may create a good escape path in the opposite lines of the tunnel for passengers in delay time duration. The results can be used for reaching to an optimized emergency ventilation scenario in tunnels due to rescue of passengers from dangers.

Keywords:

• tunnel ventilation
• fire product species
• critical ventilation velocity
• evacuation time

Notes

1 Computational Fluid Dynamics

2 Fire Dynamics Simulator