Energy science and environmental engineering
It can be concluded from the experimental result that (Figure 1) the temperature rises rapidly at the middle to bottom part in the first stage of oxidation of coal body. The points whose rate changes faster move towards the wind inlet eventually at the edges of coal body as time goes by, and finally form an open flame. The coal sample radiating intensity is low when the coal temperature is below 110°C; however, the heat release rate increases considerably when the coal temperature increases more than 110°C gradually. According to the heat transfer theory, aerodynamics theory, and the experimental data, an approximate solution of the maximum intensity of air leakage, the minimum thickness of float coal, the minimum oxygen concentration, and the maximum mean particle size can be obtained by the spontaneous combustion of coal.