EFFECT OF LOCAL VENTILATION ON CO CONCENTRATION AND AIR POLUTION OF CITY SUBWAY USING CFD

Zand-e Shiraz subway is the vehicular tunnel in the center of city. This subway is constructed to prevent Zand 230 year-old fort, mosque, Bazar and pavion (1752-1794) from damage of air pollution. The tunnel is equipped with the longitudinal ventilation system. This system contains some exhaust fans and inlet vents installed on these opening. Some pollutants are emitted by vehicle exhaust pipes. A suitable tunnel ventilation system must be capable of diluting the pollutants, especially CO, to an acceptable level in any traffic condition. In this research, bumper to bumper, slow moving traffic is considered as the least favorable traffic condition. The situation of ventilation and air pollution of the present ventilation system is analyzed. In addition, four proposed modifications are offered. Volume average, vertical and longitudinal distribution of CO concentration is obtained in each case. The second and third proposed changes can reduce volume average of CO concentration to about 2/3 of the corresponding value in the present ventilation system.

Keywords:

Air pollution , CFD , Vehicular Tunnel , CO Concentration , Ventilation