Experimental and numerical analysis of thermal comfort in high-geothermal tunnel rest rooms

In high-geothermal tunnel construction, rest rooms play a critical role in safeguarding workers’ health and operational safety. To elucidate the thermal comfort characteristics of these spaces, a comprehensive questionnaire survey was administered to 1,478 construction workers at a tunnel site in Linzhi, Tibet. The study systematically analyzed the disparity between Predicted Mean Vote (PMV) values and workers’ subjective thermal sensations, thereby establishing the thermal comfort zone and identifying an optimal temperature range of 22.0°C–26.0°C for rest rooms. Furthermore, through secondary development of ANSYS Fluent software, correlations between PMV, Predicted Percentage Dissatisfied (PPD), and a thermal comfort index (DR) were investigated across varying indoor environmental parameters. Key findings reveal that peak thermal comfort is attained at a fan speed of 2.5 m/s and an air supply angle of 75°. Notably, this study pioneers the integration of field-collected subjective data with computational fluid dynamics (CFD) simulations to refine environmental design guidelines for high-geothermal tunnel rest rooms. The proposed framework not only enhances workers’ operational comfort but also provides a replicable methodology for optimizing rest room configurations in extreme thermal environments.