Hao (Simone) Wang

This study addresses thermal comfort challenges in enclosed, high-occupancy metro carriages through systematic optimization of impinging jet ventilation parameters. Numerical simulations, validated by full-scale experiments, employed the Fiala Thermoregulation Model and Equivalent Homogeneous Temperature model for comprehensive thermal comfort evaluation. A total of 100 operating conditions were analyzed to investigate the effects of supply airflow rate, temperature, and vent height. The optimization identified two distinct locally optimal strategies (OS 1 and OS 2): a low-flow rate, low-temperature configuration (1.639 kg/s, 20.80 °C, 0.0839 m) and a high-flow rate, high-temperature configuration (2.519 kg/s, 23.19 °C, 0.0729 m). The existence of multiple optima provides operational flexibility for secondary objectives such as energy efficiency and noise reduction. Parameter sensitivity analysis established airflow rate and temperature as the dominant factors influencing thermal comfort, providing crucial guidance for control system design. Both optimal configurations achieve uniform thermal environments without draught risk while fully complying with vertical temperature standards, effectively eliminating concerns about foot-level overcooling. Comparative analysis reveals that OS 1 excels at overall performance in thermal regulation and reduces energy consumption by 13.45%, whereas OS 2 offers advantages in minimizing vertical temperature differences. This integrated assessment provides a solid basis for selecting more reliable and comprehensive parameter design solutions.