Numerical analysis of wall temperature in underground channel during pulverized coal combustion modeling

Purpose. To determine the optimal approach for evaluating the temperature characteristics of the channel wall and analyze them in numerical modeling of pulverized coal combustion. Methods. The study was conducted using numerical modeling of the pulverized coal combustion process in a cylindrical channel 30 m long and 1 m in diameter, which is formed after auger coal mining. The Ansys Fluent software was used for modeling, applying the non-premixed combustion model and the k-ε turbulence model. Calculations were performed for time intervals of 1, 12, 24, 36, and 48 hours. Findings. Analysis of the obtained temperature fields showed that the maximum temperature in the combustion zone increases from 1220ºC (1 hour) to 1540°C (24 hours). The process stabilizes by the 12th hour at a temperature of 1490ºC. It was found that the temperature in the channel rapidly decreases after 7–10 m from the inlet, stabilizing at 490–520 ºC. The primary cause of heat loss is the high thermal conductivity of the surrounding rocks. It was determined that the Twall parameter most accurately represents the actual temperature regime of the wall and allows for an assessment of the system’s thermal state. The originality. For the first time, a comprehensive analysis of the temperature field dynamics of the channel wall during prolonged pulverized coal combustion in a coal seam channel was conducted. Critical zones of heat loss and temperature stabilization were identified, allowing for the justified selection of the optimal wall temperature parameter for numerical modeling. Indicators of the percentage distribution of static temperature in the channel and the temperature of the wall around the channel over time were obtained. Practical implementation. The obtained results can be used to improve numerical modeling methodologies for underground coal combustion and co-gasification processes. The identified temperature distribution patterns enable the optimization of fuel and air supply parameters to enhance the efficiency of thermochemical conversion. The proposed approach can be applied in the design of coal seam co-gasification technologies.