Study on smoke exhaust performance in tunnel fires based on heat and smoke exhaust efficiency under the lateral centralized mode

Abstract

When a tunnel fire occurs, using quantitative indicators to evaluate the performance of smoke extraction system and determining a reasonable exhaust volume is the key to ensuring the high efficiency of the tunnel smoke extraction system. Based on the transfer mechanism in heat and mass flow rate of smoke, theoretical models are established to calculate the heat and smoke exhaust efficiency of smoke inlets in each group and the smoke extraction system under the lateral centralized smoke exhaust mode by temperature and CO concentration. FDS is used to investigate the temperature and CO concentration changes under different exhaust volumes, and the heat and smoke exhaust efficiency are obtained. The larger the exhaust volume, the higher the total heat and smoke exhaust efficiency of the smoke extraction system. However, the phenomenon of plug-holing occurs in the lower left area of the smoke inlets. With the heat release rate of 20 MW and no longitudinal ventilation, the smoke exhaust performance can be greatly improved when the single-sided exhaust volume is 180 m 3 /s, the heat and smoke exhaust efficiency at the smoke inlets can reach up to 54.2% and 47.3% respectively, and the total heat and total smoke exhaust efficiency are 51.3% and 39.7% respectively.