Migration and cooling characteristics of low-temperature gaseous CO2 in high-temperature loose coal

Abstract

To investigate the extinguishing effect of low-temperature gaseous CO2 on coal spontaneous combustion, a similar simulation experiment was designed and conducted to test its migration and cooling characteristics in high-temperature loose coal. During the injection of low-temperature gaseous CO2, the temperature along the central axis of the release port decreases rapidly. The size of the cooling range and the diffusion rate of the cooling area are inversely proportional to the distance from the center axis and directly proportional to the injection time. The injection time plays a dominant role in the cooling effect of the high temperature coal, followed by the injection position. Gaseous CO2 diffuses inside the loose coal body rapidly, filling the vicinity of the release port within 5s and the container within 30s. The average diffusion velocity of CO2 within the loose coal is 0.051 m/s. The results of this study provide a theoretical basis for the application of low-temperature carbon dioxide to combat coal fire disasters.