Experimental investigation on thermal performance of underground refuge chamber under natural convection and ventilation

Thermal performance of densely populated underground buildings is normally influenced by various factors, including the surrounding rock (SR), ventilation, and indoor heat sources. It is recognized that little experimental studies on thermal control for the above building was reported. In this article, a full-size 50-person mine refuge chamber (MRC) was newly constructed to test the thermal performance under natural convection and ventilation. The heat ducts were used to simulate the heat released from human body. Experimental results indicated that: (1) the intensity of the heat transfer between rock and air increases with the rise in heat source rate and ventilation temperature (VT), while it decreases as the initial surrounding rock temperature (ISRT) increases; (2) when considering the joint temperature control of pre-cooled SR, it is recommended to reduce the VT linearly during the evacuation period in order to ensure the thermal safety of personnel. During the non-refuge period, the cold amount should be stored as far as possible into the shallow SR body to make full use of it; (3) to ensure the thermal safety of an MRC with a capacity of 30 people for 96 h, cooling measures are required when the ISRT exceeds 21.3 °C. In addition, when the ISRT reaches 27.6 °C, the per capita ventilation is 0.19 m3/min, and the temperature is 26 °C, which can also meet the requirements. This study provides experimental verification as a basis for future research on underground space temperature control considering the influence of SR.