Temperature Response Characteristics of Coal Freezing Process Based on Thermal Conductivity Hyperbolic Model

To achieve rapid freezing of the coal body in the step during rock cross-cut coal removal by freezing method, coal thermal conductivity with different water capacities at varying freezing temperatures is experimentally tested, and the hyperbolic model of thermal conductivity is proposed. The model parameters are optimized using the artificial neural network (ANN) method, and the model can mimic the change rule about thermal conductivity with temperature during the freezing process. Meanwhile, the time-varying law during the freezing process of the coal body is numerically analyzed using the thermal conductivity hyperbolic model and heat conduction theory; simulation results are analyzed and compared with measured results. After optimizing three parameters of the thermal conductivity hyperbolic model with the ANN approach, the calculated thermal conductivity values are distributed on a 1:1 line with measured results. This indicates that combining heat conduction theory with the thermal conductivity hyperbolic model can accurately predict the time-varying characteristics of temperature during the freezing process of the coal body with moisture content. Moreover, when coal body water capacity is about 12%, and its temperature decreases the fastest during freezing process This method establishes a theoretical foundation for forecasting the temperature aging properties of rapid freezing during the rock cross-cut coal removal process.