Investigation of airflow field and air pollutants distribution in public transportation interchange in Hong Kong

In common engineering approach, the ventilation rate of the mechanical ventilation system in public transport interchange (PTI) is normally determining by the dilution method. Nevertheless, by the use of dilution method, the well-mixed condition is assumed in advance, which does not always meet the actual situations. This paper shows how the typical design of the ventilation system affects this assumption. An investigation on the airflow patterns, contaminant distributions, etc., within a typical PTI under different ventilation conditions can be provided through the cases study. The studies include the method described in design guideline on mechanical ventilation system for car park building and Control of air pollution in semi-confined public transport interchange. Moreover, the problems arising from the well-mixed assumption are thoroughly discussed and recommendation to designing the mechanical ventilation system of the PTI is given. In the study, the computational Fluid Dynamics (CFD) method is employed to analyze the airflow field and the air pollutants distribution inside the PTI as well.