This paper investigates the characteristics of lignite spontaneous combustion, with coal samples piled in cube mesh-boxes of three different sizes, placed in a constant temperature chamber and tested by the isothermal heating method. The temperature-time traces and the critical self-ignition temperature in different size coal piles are obtained. The critical self-ignition temperature is lower for larger stockpile volumes. The heating curves of coal will reach the ignition point when the set ambient air temperature is higher than the critical self-ignition temperature. On the other hand, the coal sample will not be self-ignited. Based on the conditions of the experiment, the temperature field, the air seepage field and the oxygen concentration field are simulated by the Fluent software. The three fields change with time and interact with each other in the entire experiment process.

spontaneous combustion  /  critical self-ignition temperature  /  numerical simulation  /  multi-field coupling