Experimental and numerical investigation of braking energy on thermal environment of underground subway station in China's northern severe cold regions

A large amount of heat and piston wind is generated during the train braking. The piston wind will be heated by the braking energy simultaneously, which has a significant influence on the air temperature and the flow field of subway stations and tunnels. The study conducted a train-induced experiment in Tai yuanjie (TYJ) station, and the air temperature and velocity data were recorded. Meanwhile, a train-induced numerical simulation was carried out for full-scaled model based on dynamic mesh and the theory of braking energy. The experimental data was compared with the simulation results to analyze the unsteady air temperature field and unsteady air flow field of the actual station. The results indicate that the braking energy of the train cannot be ignored in the simulation of the subway station in winter. However, the utilization of the braking energy is inefficient. To improve the utilization of the braking energy, this paper put forward one passive approach and three active approaches. The simulation results indicated that the active approaches could improve the heat utilization of braking energy significantly. Ventilation system could transport part of the piston wind to the station by fans so that it can prevent cold air entering the station.