Study on the Evolution of Thermal Properties and Oxidation Kinetics Mechanism of Coal Mass in Coalfield Fire Zones Under Ventilation-Heating Rate Synergistic Effect

This study investigates the thermophysical properties and oxidation kinetics of coalfield fire zone in Northern Shaanxi, focusing on the combined effects of ventilation and heating rate. At temperatures ranging from 30°C to 300°C, the thermal diffusivity of coal decreased from 0.095 to 0.063 mm2 /s, while specific heat capacity increased to 1.71 J/(g·K). Thermal conductivity initially dropped to 0.085 W/(m·K) at 100°C before rising to 0.113 W/(m·K) at 300°C. Thermal kinetics analysis revealed a synergistic effect between ventilation and heating rate: increased ventilation reduced the ignition temperature by 7%, enhanced combustion indices (Ci, Cb, Sc) and DSCmax. Characteristic gas such as CO, CO2, hydrocarbons concentrations rose with temperature but were diluted by high ventilation rates. A kinetic model (m = 0.0014, R2 = 0.953) was developed to quantify the oxygen-energy-heat balance. The study clarifies the oxidation-combustion mechanism of coal under varying ventilation and heating conditions, providing theoretical guidance for optimizing fire control strategies in coalfield fire zones.