CFD Analysis of Oxygen and Carbon Dioxide Recovery during Ventilation in Municipal Confined Space

Confined space is a special working place. To ensure the safety, the forced ventilation must be carried out before entering the confined space. In this paper, ventilation process in municipal heating confine space is simulated by CFD numerical simulation method, and the distribution of temperature, oxygen and carbon dioxide in municipal heating confined space during ventilation process is studied. The simulation results show that the airflow and temperature are obviously stratified in vertical direction during the ventilation. The temperature is low and the airflow velocity is high at the bottom part of the tunnel. While the temperature is high and the airflow velocity is low at the top of the tunnel. By contrast, recovery of the oxygen and carbon dioxide content is relatively faster at the bottom than it at the top. When the ventilation volume flow rates are 6000 m 3 •h −1 , 8000 m 3 •h −1 , 10000 m 3 •h −1 , 12000 m 3 •h −1 , and 14000 m 3 •h −1 respectively, the time when the temperature reach stable and gas fraction return to normal are 45 minutes, 32 minutes, 22 minutes, 15 minutes, 10 minutes respectively.