The study of the ventilation system of Pinglin tunnel

This paper studies the aerodynamics and ventilation of Pinglin tunnel, which employs a longitudinal ventilation system and uses an air interchange system as an auxiliary. The two tubes of Pinglin tunnel have opposite peak traffic cycles. The largest fresh air demand of Pinglin tunnel occurs when the uphill tube has a peak traffic with a high percentage of heavy trucks. The individual ventilation of the two tubes can be combined as a whole by common ventilation shafts and air interchange system. The less polluted tube acts as an auxiliary ventilation shaft of the more heavily polluted tube. The pollution level is highest at the locations of shaft. The ventilation requirement in each division is to guaranty that the pollution level does not exceed the legal standard. Control process is greatly simplified by setting the quantity of inflow air equals to outflow air in common shafts and interchange ducts. It has been found in this study that a smaller ventilation flow in shafts plus a larger flow in interchange ducts is the most energy saving operation mode.