Effects of exhaust methods on air distribution and respiratory pollutants diffusion characteristics in high-speed train compartments

Abstract

<p indent="0mm">A high-speed train has a large passenger volume and long running time. The optimized design of the ventilation system is of great importance to improve the car comfort and air quality in the passenger compartment. Therefore, this study establishes a full-scale car model with full load conditions based on the theory of computational fluid dynamics. The middle air supply at the top of the passenger compartment was considered as an example, the flow field structure and respiratory pollutants diffusion characteristics in the passenger compartment under the exhaust air at both ends, lower and upper exhausts, upper exhaust mode that changes the ratio of the exhaust flow on both sides were compared and analyzed. The nonuniformity coefficient, energy utilization coefficient, and ventilation efficiency indicators are used for evaluation and analysis. The results show that when the improved upper exhaust method is adopted, the comprehensive evaluation index in the passenger compartment is the best; the average indoor concentration is less than<sc>500 ppm</sc> (parts per million); the dilution factor exceeds 10000 times. When passengers and pollution sources are separated by more than two-row forward or one-row backward, the pollutant concentration is less than <sc>500 ppm,</sc> effectively controlling the front and rear diffusion distance. According to the law of pollutant diffusion, passengers in rows B and C should be avoided to ride next to each other to prevent cross-spread among passengers.