Unsteady Coupled Heat Transfer in the Air and Surrounding Rock Mass for Mine Excavations with Distributed Heat Sources

This paper presents an unsteady coupled heat transfer model in mine air and surrounding rock mass in the presence of distributed heat sources. The case of distributed heat sources is typical when analyzing the temperature distribution in mine excavations equipped with conveyor systems. For this case, the asymptotic value of the air temperature at the end of the mine excavation is determined not only by the heat exchange between the air and surrounding rock mass but also by the thermal power of distributed heat sources and the total airflow. This conclusion is confirmed by the experimental data presented in the paper for a longwall in a potash mine. We formulate the mathematical model and calculate the distribution of air parameters along the length of an excavation, considering heat release from the conveyor and surrounding rock mass. The results show that a distributed heat release is necessary for correctly calculating the air temperature in working areas. The numerical simulations allow us to recommend a redistribution of air between the haulage and conveyor roadways in the presence of distributed heat sources.