An investigation into the morphological distribution of the temperature field in loose media and its underlying principles of evolution

Abstract

The spontaneous combustion of coal in goaf has important implications for the safe mining of working faces; hence, it is crucial to prevent and control such occurrences. Here, we establish an experimental system to investigate the morphological distribution, evolution, and migration process of the temperature field of the thermal core area in systems with various particle sizes. Furthermore, we propose a high-temperature-region inversion method based on the morphological evolution model of the temperature field. Our experimental results demonstrate that particle size is a critical factor influencing the temperature field morphology under a given heating condition. During the heating stage, the isothermal surface within the thermal core area forms an ellipsoidal shape, with a transverse section comprising concentric circles, and a longitudinal section comprising ellipses. During the heat dissipation stage, the isothermal surface of the small-particle-size system encircles the thermal core area from the upper direction downwards, while the isothermal surface of the large-particle-size system encircles the thermal core area from the lower direction upwards. Moreover, the thermal core area of the large-particle-size system migrates upwards, while the thermal core area of the small-particle-size system migrates a shorter distance. Finally, we used a geometrically simplified temperature field in loose media to propose a high-temperature-region inversion method, which was verified by experiments. This study is crucial for understanding the distribution and evolution of temperature fields in loose media and predicting the formation and development of high-temperature regions.