Numerical simulation of airflow temperature field and cooling in high temperature coal seam working face

With the continuous extension of coal mining depth, the risk of heat exhaustion from high temperatures gets worse. In this paper, we first identified the main heat sources of the high-temperature coal seam working face. The effects of air supply volume on the temperature evolution of working face were then investigated by numerical simulation. The air supply volume to effectively cool the working face was calculated using a new method, sigma heat difference. A mechanical cooling method, an air cooler in the intake airway, was proposed, and the accuracy of the sigma heat difference method was confirmed through numerical simulation and field measurements. The results show that: (1) The aggregate thermal energy emitted by the heat sources located in the mining working face is 688.2177 kW, with mechanical equipment heat dissipation accounting for the main part; (2) The numerical simulation shows that the temperature of the airflow of the roadway steadily drops as the airflow velocity from the inlet airway increases. Yet extremely high inlet airflow velocities lead to narrower change ranges of the air temperature of the working face; (3) The air supply volume required to effectively cool the working face is determined by the sigma heat difference method to be 1972.2 m3/min, which provides a basis for numerical simulation of inlet air velocity for cooling; (4) The Field measurement and numerical modelling demonstrate that the sigma heat difference method is reasonable. The research conclusions provide theoretical guidance for dealing with heat hazards in coal mining faces.