Performance evaluation of air distribution systems in three different China railway high-speed train cabins using numerical simulation

Air distribution system is very important to indoor air quality (IAQ) in China railway high-speed (CRH) train cabin. Air distribution systems in three different CRH train cabins are simulated and evaluated in this paper by using the computational fluid dynamic (CFD) method. CFD models of CRH1, CRH2 and CRH5 train cabins are developed and validated basing on the field experiments in three train cabins. Flow field, temperature field, and airflow pattern in the three train cabins are investigated respectively by using the CFD models developed. Four improved performance indexes which can eliminate influences of geometric dimension are utilized to evaluate the air distribution systems in the cabins. The cough droplets dispersion processes inside the CRH train cabins are simulated to investigate the cough droplets removal ability. Simulation results show that good airflow pattern is very critical to guarantee the uniform distribution of flow field, temperature field and thermal comfort in the train cabin. The air distribution system employed in CRH5 train cabin is the most efficient among the three train cabins. Moreover, CRH5 train cabin has stronger cough droplets removal ability than CRH1 and CRH2 train cabins. Air distribution system in CRH5 train cabin should be adopted in the next generation CRH train cabin in the future.