Experimental and numerical investigation of TVOC concentrations and ventilation dilution in enclosed train cabin

Air pollution in trains is an important factor threatening human health, which has attracted more and more attention in the worldwide public health researches. In this study, one cabin of a fully enclosed train was taken as an example to conduct experimental and numerical research on pollution level and distribution characteristic of total volatile organic compound (TVOC). The results show that when the average emission rate under daily environmental conditions was taken as the reference, TVOC concentration in the cabin exceeded the limit level of Chinese Indoor Air Quality Standard by more than 4 times. The obvious pollutants accumulative phenomenon could be found at bottoms and corners under the action of airflow. Setting air inlets at the roof of the train, mean age of air ranged from 30 s to 50 s in the breathing area. The concentration of pollutants was the lowest at 2.5-5 m from the center point of the cabin structure, and the ventilation efficiency was the highest. The introduction of clean fresh air could effectively eliminate pollutants. When the complete displacement ventilation rates were 51.4 h^-1 and 28.6 h^-1, the removal efficiency of pollutants was about 0.85 and 0.48 mg/m³ per minute, respectively. This study was helpful to the improvement and optimization design of air quality and ventilation mode in trains.