Study on the thermal comfort characteristics under the vent with supplying air jets and cross-flows coupling in subway stations

The coupling air organizations between supplying air jets and platform piston winds prevail on the platforms of the subway stations without platform screen doors (PSD) all over the world. The thermal comfort characteristics under the vent are studied in this paper. Firstly, the coupling mechanism of these two airflows is described based on the cross-flow theory. Secondly, Relative Warmth Index (RWI) is selected to evaluate human thermal comfort level with dynamic coupling airflows in the transitional areas. Calculated by the RWI theory model, it can be concluded that air velocities can be enhanced to compensate the supplying air temperature increasing without affecting human thermal sensations with RWI within 0-0.15. Thirdly, experimental studies are carried out and it can be seen that the average RWI values of vertical points under the vent increase from [−0.29, −0.03] in uncoupled conditions to [0.23, 0.14] in coupling conditions, leading to human thermal sensations greatly improved. The experimental RWI values of horizontal points move into the comfort zone a lot under coupling airflows conditions, compared with the uncoupled conditions. In conclusion, the coupling airflows of supplying air jets and cross-flows can improve the transitional thermal comfort and bring forward huge energy-saving potential in air-conditioning systems by allowing the supplying air temperature to be increased in transitional subway stations.