Optimization of gravity heat pipe technology for managing temperature accumulation in gangue hills: Theoretical, numerical, and field studies

Gangue hill spontaneous combustion entails severe environmental threats. Gravity heat pipe (GHP) technology has emerged as an effective solution. This study formulated a theoretical model for deep temperature build-up in gangue hills and a numerical model for forced convective heat dissipation using GHPs. Through an in-depth exploration, the impacts of GHP arrangement parameters, ambient temperature, and wind speed on heat management efficacy were scrutinized. For the inland platform of gangue hills, an optimal 3 m GHP spacing maximized heat dissipation, while 1.5 m was optimal for slopes. When comparing different layouts, the triangular arrangement of GHPs exhibited superior heat dissipation performance to the square one. Regarding temperature variation, under calm wind conditions, GHPs decreased the volume of high-temperature zones within gangue hills by 10.79%. As the wind speed rose from 0.5 to 8 m/s, the reduction in high-temperature areas with GHPs was 46.72 times that without. Ultimately, Field trials conducted at the Xinzhi gangue hill in Shanxi, China, validated the accuracy of the theoretical model. The application of optimized parameters successfully managed the accumulated heat within the Xinzhi gangue hill. The research findings provide crucial reference points for parameter design in the management of coal gangue hills.