Outdoor air control strategy of underground railway stations

Analyses three kinds of outdoor air control modes of environment control system in underground railway stations by theoretical and field test methods. The main findings are that the single fan system cannot supply mechanical outdoor air when the outdoor air rate is insufficient, moreover, the system requires better air-tightness of dampers. In the conventional system with outdoor air damper control mode, the linearity of outdoor air rate adjustment is poor, and it is difficult to accurately control the outdoor air rate. Instead, using supply fan and return/exhaust fan to control the mechanical outdoor air can obtain better adjustment linearity and realize accurate control of outdoor air rate.