Influence of heat pipe layout parameters on the cooling effect of spontaneous combustion coal gangue dumps

Existing research has found that the number, insertion depth and angle, filling rate, and working fluid of heat pipe (HP) can affect the distribution of temperature field inside coal gangue dumps. However, there is relatively little research on the optimal arrangement of heat pipes (HPs) in coal gangue dumps. In response to the above issues, based on the theoretical model of HP heat transfer, the influence of HPs layout on the temperature field of coal gangue dumps is analyzed through a combination of numerical simulation and experiments, and the optimal layout of HPs is obtained. The results show that the presence of HPs can change the heat conduction path in a coal gangue dump and help the coal gangue dumps to dissipate heat in time. As the insertion spacing of the HPs decreases and the insertion depth of the HPs increases, the area of the spontaneous combustion danger zone (SCDZ) decreases, the maximum temperature value (T_max) decreases, and the better the cooling effect. The influence of the insertion spacing of HPs on the spontaneous combustion volume of coal gangue dumps is greater than the influence of the insertion depth of HPs. When the insertion spacing of HPs is 3 m and the insertion depth of HPs is 7 m, the spontaneous combustion volume and the highest temperature point respectively decrease by 11755m³ and 302.57 ℃, and the cooling effect of coal gangue dumps is the best. Consequently, this study provides a reference for the design and optimization of coal gangue fire fighting engineering with HP application in the future.