Simulation test study on temperature field evolution of coal spontaneous combustion in gob

In order to study the evolution law of temperature field during spontaneous combustion process of coal in gob of rhe working face, based on geometric similarity and the principle of coal spontaneous combustion, a similar simulation test device for the temperature field distribution in the gob was developed.After crushing the large lump coal samples collected on site, the mixed coal with particle size less than 30 mm were selected for filling. Heat sources and measuring points were set up to simulate the heat transfer process of coal spontaneous combustion in gob, and the distribution law of temperature field inside loose coal body, the effect of heat source temperature on the heat transfer law of loose coal body, and the distribution law of temperature field of Y-shaped ventilated gob were studied. The test results show that under the condition of no convection, the heat transfer from the heat source to the surrounding coal body is isotropic.With the increase of the heat source temperature, the heat transfer capacity of the heat source in the loose coal rapidly increases in a non-linear form, and increase rate is getting larger and larger. The relationship between the temperature of a measuring point around the constant temperature heat source and the distance and time of the constant temperature heat source is that, when the distance or time is less than the value of parabolic symmetry axis, it conforms to the quadratic function relationship, and when the value is greater than the value of parabolic symmetry axis, the temperature of the measuring point is basically stable. In the process of coal spontaneous combustion, the high temperature point in the spontaneous combustion process of coal will migrate to the oxygen enrichment area in an accelerated manner. Affected by the pressure and suction effect of the fire wind, the migration effect of the upper area of the fire source is more obvious.