Numerical simulation of synergistic geothermal energy extraction and roadway airflow cooling through buried tubes in the surrounding rock in deep high-temperature mines

The issue of heat hazard caused by high-temperature surrounding rock in deep mines is becoming increasingly prominent, while the potential for geothermal energy exploitation form surrounding rock is considerable. Therefore, the synergetic technology of mine geothermal mining and heat hazard prevention has garnered significant attention. Previous studies have primarily focused on the coupled effects of open-loop systems and formation cooling, with limited exploration of the mechanisms underlying the cooling effects of geothermal extraction from closed-loop systems on roadway airflow. This research utilizes COMSOL software to establish a coupled heat transfer and seepage model for the synergistic implementation of heat extraction and cooling through buried tubes within the surrounding rock. The heat transfer behavior of surrounding rock, the cooling effect on airflow, and the geothermal extraction performance during long-term heat transfer processes are studied. The results indicate that when groundwater seeps horizontally and perpendicularly to the axial direction of the roadway, and a single buried tube is located in the upstream seepage zone of the roadway, the cold domain range on the downstream side of the fluid cooling influence zone in the buried tube is significantly expanded, which is more likely to overlap with the cold domain range on the upstream side of the airflow cooling influence zone in the roadway and form a cold accumulation, resulting in the best cooling effect of the airflow. As the distance between the buried tube and roadway increases, the cooling effect of the airflow decreases, and the fluid temperature at the outlet of the buried tube and thermal power increase, but the improvement in both becomes negligible once the distance reaches a certain value. Lowering the fluid temperature at the inlet of the buried tube has a significant effect on improving the cooling effect of the airflow and thermal power, but it can cause a decrease in the fluid temperature at the outlet of the buried tube. Reducing the fluid mass flow rate of the buried tube can significantly increase the fluid temperature at the outlet of the buried tube, while increasing the fluid mass flow rate of the buried tube can enhance the cooling effect of the airflow and thermal power, but the impact on both is no longer significant after the fluid mass flow rate of the buried tube increases to a certain value.