Temperature response of coal fracture induced by three-dimensional stress field

•The linear relationship between the stress and internal temperature of coal is obtained.•The equation for the effect of stress on temperature was derived and proofed.•More direct evidence is provided for the temperature difference induced by cracks. The release of thermal phenomena during coal fracture is well-established. However, current understanding of the temperature variations induced by stress fields in coal remains limited. A triaxial test was employed to explore the internal temperature response to stress and cracks in coal by incorporating moment tensor inversion for the crack distribution analysis. An equation describing the stress-induced temperature variations was derived and validated using thermodynamic parameters. The impact of coal fractures on temperature was assessed by comparing the values at different locations. The results show a strong, positive linear correlation between stress and internal temperature, indicating an increase in temperature with rising stress. The calculated temperature variations closely aligned with the observations in crack-free areas. Temperature differentiation occurred in regions with concentrated shear cracks. Significant shear damage led to a sudden increase owing to frictional and thermoelastic heating. These findings are significant for predicting spontaneous coal combustion.