Study on surrounding rock thermal physical properties on thermal comfort in a ventilated underground refuge chamber

Thermal comfort of underground buildings is related to human health, surrounding rock is a core factor determining the underground thermal environment. However, previous studies have rarely focused on the impact of surrounding rock conditions on thermal comfort. To explore the impact mechanism of surrounding rock conditions on the thermal comfort distribution of underground buildings, this paper establishes a numerical model of a 30-person underground refuge chamber (URC) based on Fluent. Apply an ice storage device to URC for experimentation to verify the accuracy of the model. Four factors are selected, including ventilation rate (VR), surrounding rock thermal conductivity, density and specific heat capacity. Using a user defined function (UDF) program, four thermal comfort indicators are evaluated under cooling compressed air: average air temperature, head-to-foot temperature difference, PMV-PPD, and draft rate (DR). The results show that: (I) When the VR is 360 m3/h and the average inlet temperature of the device is 24.18 degrees C, the average outlet temperature of the device is 15.63 degrees C within 24 h, the average air temperature controlled by URC is maintained at 27.00 degrees C; (II) DR increases with the increase of VR, when the VR exceeds 360 m3/h, the DR at ground level exceeds 40 %, and the draft sensation is unsatisfactory; (III) The average air temperature, head-to-foot temperature difference, and PMV-PPD values in the URC decrease with the increase of VR, surrounding rock thermal conductivity, density and specific heat capacity, gradually approaching a comfortable state of thermal sensation.