CFD design of ventilation system for large underground bus terminal in Macau Barrier Gate

The effective design of ventilation systems for underground buildings is critical for human comfort and health. In this paper, a mechanical ventilation system is proposed to solve the problems of high temperature and exhaust pollution in the Macau Barrier Gate underground bus terminal. The vents have been reasonably located at the top of the bus terminal, and the dilution method is used to calculate the required exhaust and supply ventilation rates. Two types of bus terminal models (with and without ventilation system) were constructed and simulated under two conditions (March and July) using computational fluid dynamics (CFD). For the bus terminal without ventilation system, the ranges of the computed air temperature and CO concentration at the monitoring points are consistent with the measurements. The computational results reveal that warm air and pollutants are confined inside owing to the circulating flow formed in the bus terminal without ventilation system, resulting in high temperature and air pollution. In contrast, transverse flow is formed with the installation of the ventilation system designed in this study, significantly decreasing the indoor air temperature (by 3-5 °C) and air pollution (to permissible air-quality limitation). This demonstrated that the ventilation system designed is effective in decreasing air temperature and air pollution in the underground bus terminal.