Air distribution and thermal environment optimization on subway platform using an innovative attached ventilation mode

Abstract Subway systems are extensively used due to their safety and convenience. Scientific and reasonable air distribution is necessary for creating a comfortable environment on the subway platform. In the present study, three ventilation modes (four-side slot outlets of attached ventilation (FSOAV), both-side slot outlets of attached ventilation (BSOAV), and mixing ventilation (MV)) were investigated based on numerical methods. Visualization experiments were conducted to characterize the attached ventilation airflow. A series of evaluation indexes, including the air velocity, temperature, air diffusion performance index (ADPI), and relative warmth index (RWI), were utilized to assess the ventilation effects of the three modes. The average temperatures among the three modes were 29.09 °C, 29.85 °C, and 29.18 °C; the ADPI values were 81.28%, 84.78%, and 55.89%; and the RWI values were 0.236, 0.256, and 0.239, respectively. These results demonstrate that FSOAV outperforms BSOAV and MV in terms of air distribution and thermal environment. Thus, FSOAV is recommended for application on subway platforms. Considering the actual layout of the construction, the positional distribution and width of air outlets were discussed to optimize the ventilation performance of FSOAV. The thermal environment of attached ventilation with double-row air outlets is better than that with single-row air outlets, and the increase in velocity contributes to the uniform diffusion of airflow in attached ventilation. This research provides design references for ventilation design in subway stations.